Chapter I

ORGANIC AND INORGANIC ENVIRONMENTAL POLLUTANTS IN AIR

AND WATERS. SONIC AND ELECTROMAGNETIC POLLUTION

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I.1. AIR POLLUTANTSMaria José SANZ, José Vicente CHORDÁ

Air pollution started when tribesmen learned to use fire, and filled the air inside their living quarters with the products of incomplete combustion. But the biggest step forward was the Industrial Revolution, thus the predominant air pollution in the 19th century was smoke and ash from the burning of coal or oil in the boiler furnaces of stationary power plants, locomotives, vessels, home heating fireplaces and furnaces. During the 20th century, after recognition of the problem by countries like Great Britain and the United States, there were great changes in the technology of both the production of air pollution and its control, but not significant changes in the limiting legislation, regulations and understanding of the problem. But, as cities and industry grew in size, the problem increased in severity. Since the 30s the other air pollution problems as well as solutions up to some extent emerged. In the following sections are described the main air pollutants and problems identified today. Due to their different nature, the pollutants are separated in organic and inorganic compounds.

I.1.1. ORGANIC AIR POLLUTANTS

I.1.1.1. Volatile Organic Compounds (VOCs)

Volatile Organic Compounds are substances that contain carbon that evaporates easily. VOCs can be from natural or anthropogenic sources. Anthropogenic VOCs are present in exhaust fumes, cigarette smoke, synthetic materials and household chemicals, and include benzene, formaldehyde and polynuclear aromatic hydrocarbons (PAH).

VOCs are involved in the formation of ground level ozone and in the depletion of the ozone layer. They also contribute to the greenhouse effect, photochemical oxidants produced from the use of VOCs are greenhouse gases. Only the most important VOCs are included below.

Aromatic hydrocarbons.The most abundant aromatic hydrocarbons in urban atmospheres are benzene,

toluene and xylenes, and trimethylbenzenes. Benzene; the chemical formula for benzene is C6H6, and it has a molecular

weight of 78.11 g/mol. (US EPA, 2002). Benzene occurs as a volatile, colorless,

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highly flammable liquid, it has a sweet odor with an odor threshold of 1.5 ppm (5 mg/m3).

It is a VOC that is a minor constituent of petrol. The main sources of benzene in the atmosphere in Europe are the distribution and combustion of petrol. Of these, combustion by petrol vehicles is the single biggest source (70% of total emissions).

Benzene is present in petrol but not diesel. Hydrocarbons including benzene are emitted during refueling, by evaporating from fuel tanks and exhausts and as unburnt hydrocarbons in exhausts. Benzene is also present in cigarette smoke and in some glues and cleaning products. Acute (short-term) inhalation exposure of humans to benzene may cause drowsiness, dizziness, headaches, as well as eye, skin, and respiratory tract irritation, and, at high levels, unconsciousness.  Chronic (long-term) inhalation exposure has caused various disorders in the blood, including reduced numbers of red blood cells and aplastic anemia, in occupational settings.  Reproductive effects have been reported for women exposed by inhalation to high levels, and adverse effects on the developing fetus have been observed in animal tests.  Increased incidences of leukemia (cancer of the tissues that form white blood cells) have been observed in humans occupationally exposed to benzene.

Xylene, m-, o-, and p-Xylene are the three isomers of xylene; commercial or mixed xylene usually contains about 40-65% m-xylene and up to 20% each of o- and p-xylene and ethylbenzene. Mixed xylenes are colorless liquids that are practically insoluble in water and have a sweet odor. The odor threshold for m-xylene is 1.1 ppm. The chemical formula for mixed xylenes is C8H10 (http://www.epa.gov/ttn/atw/hlthef/).

Xylenes are released into the atmosphere as fugitive emissions from industrial sources, from auto exhaust, and through volatilization from their use as solvents.  Acute (short-term) inhalation exposure to mixed xylenes in humans results in irritation of the eyes, nose, and throat, gastrointestinal effects, eye irritation, and neurological effects.  Chronic (long-term) inhalation exposure of humans to mixed xylenes results primarily in central nervous system (CNS) effects, such as headache, dizziness, fatigue, tremors, and incoordination; respiratory, cardiovascular, and kidney effects have also been reported. 

Toluene, the chemical formula is C6H5CH3, and its molecular weight is 92.15 g/mol. Toluene occurs as a colorless, flammable, refractive liquid, that is slightly soluble in water. Toluene has a sweet, pungent odor, with an odor threshold of 2.9 parts per million (ppm).

Toluene’s major use is to be added to gasoline to improve octane ratings, it is also used to produce benzene and as a solvent in paints, coatings, adhesives, inks, and cleaning agents. It has a minor importance in the production of polymers used to make nylon, plastic soda bottles, polyurethanes and for pharmaceuticals, dyes, cosmetic nail products, and the synthesis of organic chemicals.

Exposure to toluene may occur from breathing ambient or indoor air.  The central nervous system (CNS) is the primary target organ for toluene toxicity in both

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humans and animals for acute (short-term) and chronic (long-term) exposures. CNS dysfunction and narcosis have been frequently observed in humans acutely exposed to toluene by inhalation; symptoms include fatigue, sleepiness, headaches, and nausea.  CNS depression has been reported to occur in chronic abusers exposed to high levels of toluene. Chronic inhalation exposure of humans to toluene also causes irritation of the upper respiratory tract and eyes, sore throat, dizziness, and headache.   Human studies have reported developmental effects, such as CNS dysfunction, attention deficits, and minor craniofacial and limb anomalies, in the children of pregnant women exposed to toluene or mixed solvents by inhalation. Reproductive effects, including an association between exposure to toluene and an increased incidence of spontaneous abortions, have also been noted.  However, these studies are not conclusive due to many confounding variables. (http://www.epa.gov/ttn/atw/hlthef/toluene.html)

Carbonyl CompoundsThe carbonyl compounds of tropospheric interest are formaldehyde,

acetaldehyde, acetone, 2- butanone, 1,3-butadiene among others.Formaldehyde is a colorless gas with the chemical formula CH2O and the

molecular weight 30.03 g/mol. The vapor pressure for formaldehyde is 10 mm Hg at -88 °C, and its log octanol/water partition coefficient (log Kow) is -0.65. Formaldehyde is a colorless gas with a pungent, suffocating odor at room temperature; the odor threshold for formaldehyde is 0.83 ppm. Formaldehyde is readily soluble in water at room temperature.

It is emitted from foam insulation, chipboard, plywood, some fabrics, motor exhausts, bonfires and cigarettes; it is also used mainly to produce resins used in particleboard products and as an intermediate in the synthesis of other chemicals. Exposure to formaldehyde may occur by breathing contaminated indoor air, tobacco smoke, or ambient urban air.  Acute (short-term) and chronic (long-term) inhalation exposure to formaldehyde in humans can result in respiratory symptoms, and eye, nose, and throat irritation.  Limited human studies have reported an association between formaldehyde exposure and lung and nasopharyngeal cancer. Animal inhalation studies have reported an increased incidence of nasal squamous cell cancer.(http://www.epa.gov/ttn/atw/hlthef/formalde.html)

1,3-butadiene is a colorless gas with a mild gasoline-like odor. The odor threshold for 1,3-butadiene is 1.6 parts per million (ppm). The chemical formula for 1,3-butadiene is C4H6, and the molecular weight is 54.09 g/mol. Like benzene, is a VOC emitted into the atmosphere principally from fuel combustion of petrol and diesel in vehicles. 1,3-butadiene is also an important chemical in certain industrial processes, particularly the manufacture of synthetic rubber. Acute (short-term) exposure to 1,3-butadiene by inhalation in humans results in irritation of the eyes, nasal passages, throat, and lungs.  Epidemiological studies have reported a possible

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association between 1,3-butadiene exposure and cardiovascular diseases. Epidemiological studies on workers in rubber plants have shown an association between 1,3-butadiene exposure and increased incidence of leukemia. Animal studies have reported tumors at various sites from 1,3-butadiene exposure.(http://www.epa.gov/ttn/atw/hlthef/butadien.html)

Polycyclic Aromatic HydrocarbonsPolycyclic aromatic hydrocarbons (PAHs) are a class of very stable organic

molecules made up of only carbon and hydrogen. These molecules are flat, with each carbon having three neighboring atoms much like graphite. The structures of a variety of representative PAHs can be seen in Figure I.1.1. PAHs are emitted from coke production, coal burning and motor vehicles. With the introduction of smoke control areas and the decline in the use of coal in domestic heating atmospheric concentrations have fallen. Some PAHs are carcinogenic, but with decline in overall concentrations, adverse effects are only likely in an occupational situation (Murley, 1995).

These molecules are highly carcinogenic but they are also very common. They are a standard product of combustion from automobiles and airplanes and some (such as benzo[a]pyrene) are present in charcoal broiled hamburgers.

Figure I.1.1. Structures of a variety of representative PAHs. A database of PAHs can be found at: http://chrom.tutms.tut.ac.jp/JINNO/DATABASE/00alphabet.html

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I.1.1.2. Other Compounds

Methane (CH4(g)) is the most reduced form of carbon in the air. It is also the simplest and most abundant hydrocarbon and organic gas. Methane is a greenhouse gas that absorbs thermal-IR radiation 25 times more efficiently, molecule for molecule, than CO2(g), but the mixing ratios of carbon dioxide are much larger than are those of methane.

Methane slightly enhances ozone formation in photochemical smog, but, because the incremental ozone produced from methane is small in comparison with ozone produced from other hydrocarbons, methane is a relatively unimportant component of photochemical smog. In the stratosphere, methane has little effect on the ozone layer, but its chemical decomposition provides one of the few sources of stratospheric water vapor. Neither the emission nor ambient concentration of methane is regulated in any country.

Table I.1.1 summarizes the sources and sinks of methane. Methane is produced in anaerobic environments, where methanogenic bacteria consume organic material and excrete methane. Ripe anaerobic environments include rice paddies, landfills, wetlands, and the digestive tracts of cattle, sheep, and termites.

Table I.1.1. Sources and Sinks of Atmospheric Methane

Sources SinksMethanogenic bacteria (lithotrophic autotrophs)Natural gas leaks during fossil-fuel miningand transportBiomass burningFossil-fuel combustionKinetic reaction

Kinetic reactionTransfer to soils and ice capsMethanotrophic bacteria (conventionalheterotrophs)

Methane is also produced in the ground from the decomposition of fossilized carbon. The resulting natural gas, which contains more than 90 percent methane, often leaks to the air or is harnessed and used for energy. Methane is also produced during biomass burning, fossil-fuel combustion, and atmospheric chemical reactions. Its sinks include chemical reactions, transfer to soils, ice caps, the oceans, and consumption by methanotrophic bacteria. The effective lifetime of methane due to chemical reaction is about 8 to 12 years, which is small in comparison with the lifetimes of other organic gases. Because methane is relatively insoluble, its dissolution rate into ocean water is slow. Approximately 80 percent of the methane in the air today is biogenic in origin; the rest originates from fuel combustion and natural gas leaks.

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Methane's average mixing ratio in the troposphere is near 1.8 ppmv, which is an increase from about 0.8 ppmv in the mid-1800s (Ethridge et al., 1992). Its tropospheric mixing ratio has increased steadily due to increased biomass burning, fossil-fuel combustion, fertilizer use, and landfill development. Mixing ratios of methane are relatively constant with height in the troposphere, but decrease in the stratosphere due to chemical loss. At 25 km, methane's mixing ratio is about half that in the troposphere. Methane has no harmful human health effects at typical outdoor or indoor mixing ratios.

I.1.2. INORGANIC AIR POLLUTANTS

Today the atmosphere below 100 km contains only a few well-mixed gases that, together, make up more than 99 percent of all gas molecules in this region. These well-mixed gases are called fixed gases because their mixing ratios do not vary much in time or space respect to their magnitude. Nevertheless, it is the variable gases, whose mixing ratios are small but vary in time and space, that are the most important gases with respect to air pollution issues.

I.1.2.1. Fixed Gases

Table I.1.2 gives the volume mixing ratios of fixed gases in the atmosphere up to 100 km. At any altitude, O2(g) makes up about 20.95 percent and N2(g) makes up about 78.08 percent of all non-water gas molecules by volume. Although the mixing ratios of these gases are constant with increasing altitudes, their partial pressures decrease with increasing altitude because air pressure decreases with increasing altitude, and O2(g) and N2(g) partial pressures are constant fractions of air pressure.

Table I.1.2.Volume Mixing Ratios of Fixed Gases in the Lowest 100 km of the Earth's Atmosphere

Gas Name Chemical Formula Volume Mixing RatioPercent ppmv

Molecular nitrogen N2(g) 78.08 780,000

Molecular oxygen O2(g) 20.95 209,500

Argon Ar(g) 0.93 9,300Helium Ne(g) 0.0015 15Neon He(g) 0.0005 5

Krypton Kr(g) 0.0001 1Xenon Xe(g) 0.000005 0.05

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Together, N2(g) and O2(g) make up 99.03 percent of all gases in the atmosphere by volume. Argon (Ar) makes up most of the remaining 0.97 percent. Argon, the "lazy gas," is colorless and odorless. Like other noble gases, it is inert and does not react chemically. Other fixed but inert gases present in trace concentrations include neon, helium, krypton, and xenon.

I.1.2.2. Variable Gases

Gases whose volume mixing ratios change in time and space are variable gases. Table I.1.3 summarizes the volume mixing ratios of some variable gases in the clean troposphere, the polluted troposphere (e.g., urban areas), and the stratosphere. Many organic gases degrade chemically before they reach the stratosphere, so their mixing ratios are low in the stratosphere.

Table I.1.3. Volume Mixing Ratios of Some Variable Gases in Three Atmospheric Regions. Organic gases are included in the table although treated in section I.1.1.

Gas Name Chemical Formula

Volume Mixing Ratio (ppbv)Clean

TropospherePolluted

Troposphere Stratosphere

InorganicWater vapor

Carbon dioxideCarbon

monoxideOzone

Sulfur dioxideNitric oxide

Nitrogen dioxideCFC-12

H2O(g)CO2(g)CO(g)O3(g)

SO2(g)NO(g)NO2(g)

CF2Cl2(g)

3,000-4.0(+7)a

365,00040-20010-1000.02-1

0.005-0.10.01-0.3

0.55

5.0(+6)-4.0(+7)365,000

2,000-10,00010-3501-30

0.05-3000.2-200

0.55

3,000-6,000365,00010-60

1,000-12,0000.01-1

0.005-100.005-10

0.22

Organic

MethaneEthaneEthene

FormaldehydeTolueneXylene

Methyl chloride

CH4(g)C2H6(g)C2H4(g)

HCHO(g)C6H5CH3(g)

C6H4(CH3)2(g)CH3CI(g)

1,8000-2.50-1

0.1-1——

0.61

1,800-2,5001-501-301-2001-301-300.61

150-1,700—————

0.36ª4.0(+7) means 4.0 x 107- indicates that the volume mixing ratio is negligible, on average.

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In addition to the most important gases mentioned in table I.1.3., there are other gaseous compounds that can also induce air pollution problems that in the past where much more important in Europe, and now are relevant in certain non-developed countries in the world. This is the case of Hydrogen fluoride (HF(g)) and up to some regard Hydrogen Chloride (HCl(g)).

I.1.2.3. Characteristics of Selected Gases and Aerosol Particle Components

Table I.1.4 lists gases and aerosol particle components relevant to each of five “main” air pollution problems identified up today. The table indicates that each air pollution problem involves a different set of pollutants, although some pollutants are common to two or more problems. A few gases and aerosol particle components listed in Table I.1.4 are discussed in terms of their relevance, abundance, sources, sinks, and health effects.

Table I.1.4. Some Gases and Aerosol Particle Components Important for Specified Air Pollution Topics

Indoor Air Pollution

Outdoor Urban Air Pollution Acid Deposition Stratospheric

Ozone Reduction

Global Climate Change

GasesNitrogen dioxideCarbon monoxide

FormaldehydeSulfur dioxideOrganic gases

Radon

OzoneNitric oxide

Nitrogen dioxideCarbon monoxide

EtheneTolueneXylenePAH

Sulfur dioxideSulfuric acid

Nitrogen dioxideNitric acid

Hydrochloric acidCarbon dioxide

OzoneNitric oxideNitric acid

Hydrochloric acidChlorine; nitrate

CFC-11CFC-12

Water vaporCarbon dioxideMethaneNitrous oxideOzone

CFC-11CFC-12

Aerosol Particle ComponentsBlack carbon

Organic matterSulfate Nitrate

AmmoniumAmmoniumAllergensSoil dustAsbestosSea spray

Fungal sporesTobacco smoke

Black carbon Organic matter Sulfate; Nitrate

Ammonium; Soil dust; Sea spray; Tire particles;

Lead

SulfurNitrate

Chloride

ChlorideSulfurNitrate

Black carbon Organic

matter Sulfur Nitrate

AmmoniumSoil dustSea spray

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Water VaporThe water vapor (H2O(g)) is the most important variable gas in the air. It is a

greenhouse gas that readily absorbs thermal-IR radiation, but it is also a vital link in the hydrologic cycle on Earth. As a natural greenhouse gas, it is much more important than is carbon dioxide for maintaining a climate suitable for life on Earth. Water vapor is not considered an air pollutant; thus, no regulations control its concentration or emission.

The main source is evaporation from the oceans. Approximately 85 percent of water vapor originates from ocean-water evaporation. Table I.1.5 summarizes the sources and sinks of water vapor.

Table I.1.5. Sources and Sinks of Atmospheric Water Vapor

Source SinkEvaporation from the oceans, lakes, rivers, and soilSublimation from sea ice and snow

Transpiration from plant leaves

Kinetic reaction

Condensation to liquid water in clouds

Vapor deposition to ice crystals in cloudsTransfer to oceans, ice caps, and soils

Kinetic reaction

The water vapor has no harmful effects on humans. Liquid water in aerosol particles indirectly causes health problems when it comes in contact with pollutants because many gases dissolve in liquid water. Small drops can subsequently be inhaled, causing health problems in some cases.

Carbon DioxideCarbon dioxide (CO2(g)) is a colorless, odorless, natural greenhouse gas, that is

pointed out as responsible for much of the global warming that has occurred to date. It is not an important outdoor air pollutant in the classic sense because it does not chemically react to form further products nor is it harmful to health at typical mixing ratios. CO2(g) plays a subtle role in stratospheric ozone depletion because global warming near the Earth's surface due to CO2(g) enhances global cooling of the stratosphere, and such cooling feeds back to the ozone layer. Mixing ratios of carbon dioxide are not regulated in any country. CO2(g) emission controls are the subject of an ongoing effort by the international community to reduce global warming.

Figure I.1.2. shows how outdoor CO2(g) mixing ratios have increased steadily since 1958 at the Mauna Loa Observatory, Hawaii. Average global CO 2 (g) mixing ratios have increased from approximately 280 ppmv in the mid-1800s to approximately 370 ppmv today. The yearly increases are due to increased CO2(g) emission from fossil-fuel combustion. The seasonal fluctuation in CO2(g) mixing ratios is due to

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photosynthesis and bacterial decomposition. When annual plants grow in the spring and summer, photosynthesis removes CO2(g) from the air. When such plants die in the fall and winter, their decomposition by bacteria adds CO2(g) to the air. Typical indoor mixing ratios of CO2(g) are 700 to 2,000 ppmv, but can exceed 3,000 ppmv when un-ventilated appliances are used (Arashidani et al., 1996).

Figure I.1.2. Yearly and seasonal fluctuations in carbon dioxide mixing ratio at Mauna Loa Observatory, Hawaii, since 1958. Data for 1958-1999 from Keeling and Whorf (2000) and from 2000. Source: http://www.visionlearning.com/library/

Outdoor mixing ratios of CO2(g) are too low to cause noticeable health problems. In indoor air, CO2(g) mixing ratios may build up enough to cause some discomfort, but doses higher than 15,000 ppmv are necessary to affect human respiration. Mixing ratios higher than 30,000 ppmv are necessary to cause headaches, dizziness, or nausea (Schwarzberg, 1993). Such mixing ratios do not generally occur.

Carbon MonoxideCarbon monoxide (CO(g)) is a tasteless, colorless, and odorless gas. Although

CO(g) is the most abundantly emitted variable gas aside from CO2(g) and H2Og), it plays a small role in ozone formation in urban areas. In the background troposphere, it plays a larger role in ozone formation. CO(g) is not a greenhouse gas, but its emission and oxidation to CO2(g) affect global climate. CO(g) is not important with respect to

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stratospheric ozone reduction or acid deposition. CO(g) is an important component of urban and indoor air pollution because it has harmful short-term health effects.

Table I.1.6 summarizes the sources and sinks of CO(g). A major source of CO(g) is incomplete combustion in automobiles, trucks, and airplanes.

Table I.1.6. Sources and Sinks of Atmospheric Carbon Monoxide

Sources SinksFossil-fuel combustionBiomass burning Photolysis and kinetic reactionPlants and biological activity in oceans

Kinetic reaction to carbon dioxide

Transfer to soils and ice capsDissolution in ocean water

CO(g) emission sources include wildfires, biomass burning, non-transportation combustion, some industrial processes, and biological activities. Indoor sources of CO(g) include water heaters, coal and gas heaters, and gas stoves. The major sink of CO(g) is chemical conversion to CO2(g). It is also lost by deposition to soils and ice caps and dissolution in ocean water. Because it is relatively insoluble, its dissolution rate is slow.

Mixing ratios of CO(g) in urban air are typically 2 to 10 ppmv. On freeways and in traffic tunnels, they can rise to more than 100 ppmv. Typical CO(g) mixing ratios inside automobiles in urban areas range from 9 to 56 ppmv (Finlayson-Pitts and Pitts, 1999). In indoor air, hourly average mixing ratios can reach 6-12 ppmv when a gas stove is turned on (Samet et al., 1987). In the absence of indoor sources, CO(g) indoor mixing ratios are usually less than are those outdoors (Jones, 1999). In the free troposphere, CO(g) mixing ratios vary from 50 to 150 ppbv.

Exposure to 300 ppmv of CO(g) for one hour causes headaches; exposure to 700 ppmv of C0(g) for one hour causes death, CO(g) poisoning occurs when it dissolves in blood and replaces oxygen as an attachment to hemoglobin (Hb(aq)), an iron-containing compound. The conversion of O2Hb(aq) to COHb(aq) (carboxyhemoglobin) causes suffocation. CO(g) can also interfere with O2(g) diffusion in cellular mitochondria and with intracellular oxidation (Gold, 1992). For the most part, the effects of CO(g) are reversible once exposure to CO(g) is reduced. Following acute exposure, however, individuals may still express neurological or psychological symptoms for weeks or months, especially if they become unconscious temporarily (Choi, 1983).

OzoneOzone (O3(g)) is a relatively colorless gas at typical mixing ratios. Ozone

exhibits an odor when its mixing ratio exceeds 0.02 ppmv. In urban smog or indoors, it is considered an air pollutant because of the harm that it does to humans, animals, plants, and materials. It is regulated in many other countries including the EU. In the

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stratosphere, the ozone's absorption of UV radiation provides a protective shield for life on Earth. Although ozone is considered to be "good" in the stratosphere and "bad" in the boundary layer, ozone molecules are the same in both cases.

Ozone is not emitted. Its only source into the air is chemical reaction. Sinks of ozone include reaction (with most of organic surfaces preferable), transfer to soils and ice caps, and dissolution in ocean waters. Because ozone is relatively insoluble, its dissolution rate is relatively slow. Table I.1.7 summarizes the sources and sinks of ozone.

Table I.1.7. Sources and Sinks of Atmospheric Ozone.

Sources SinksChemical reaction of O(g) with O2(g)

PhotolysisKinetic reactionTransfer to soils and ice capsDissolution in ocean water

There is controversy about ozone background mixing ratios in the free troposphere, but they are in the range of 20 to 40 ppbv near sea level and 30 to 70 ppbv at higher altitudes. Ozone is a pollutant that is produced in the atmosphere and therefore picks are not necessarily related to urban or industrial areas, and may be seen in suburban or rural areas, downwind areas from where the precursors are emitted (Millán et al 1992, 1997, 2000, 2002). In urban air, ozone mixing ratios range from less than 0.01 ppmv at night to 0.50 ppmv (during afternoons downwind from the most polluted cities world wide, i.e. Los Angeles), with typical values of 0.15 ppmv during moderately polluted afternoons. It has a typical daily cycle that are characteristic of position with respect to the topography and the location where the precursors are emitted (Figure I.1.3.) Indoor ozone mixing ratios are almost always less than are those outdoors. In the stratosphere, peak ozone mixing ratios are around 10 ppmv.

Ozone causes headaches at mixing ratios greater than 0.15 ppmv, chest pains at mixing ratios greater than 0.25 ppmv, and sore throat and cough at mixing ratios greater than 0.30 ppmv. Ozone decreases lung function for people who exercise steadily for more than an hour while exposed to concentrations greater than 0.30 ppmv. Symptoms of respiratory problems include coughing and breathing discomfort. Small decreases in lung function affect people with asthma, chronic bronchitis, and emphysema. Ozone may also accelerate the ageing of lung tissue. At levels greater than 0.1 ppmv, ozone affects animals by increasing their susceptibility to bacterial infection. It also interferes with the growth of plants and trees and deteriorates organic materials, such as rubber, textile dyes and fibers, and some paints and coatings (U.S. EPA, 1978).

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Figure I.1.3. Processes that result in typical Ozone cyclesSummary of recirculation processes in the East coast of Spain after MECAPIP (Meso-meteorological Cycles of Air Pollution in the Iberian Peninsula) and RECAPMA (Regional Cycles of Air Pollution in the West Central Mediterranean Area) projects as well as simplified model of Derwent & Davies (Derwent & Davies, 1994) relating NO emissions NO and Ozone production.

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Ozone increases plant and tree stress and their susceptibility to disease, infestation, and death (Sanz & Millan, 2000). Ozone is absorbed through the leaf pores, and damages the cell membranes and the cells collapse as a result. Symptoms vary from stippling or flecking to bleached or dead areas. Upper leaf surfaces may have white to tan, purple or black flecking, which may also be visible on the lower leaf surface of some plants. Damage usually occurs when ozone concentrations are highest: in mid to late summer, during the early afternoon when the air is still. Symptoms are often more severe on leaves exposed to direct sunlight and on plants growing in moist, light soils with good fertility. Older leaves are most sensitive.

Sulfur DioxideSulfur dioxide (SO2(g)) is a colorless gas that exhibits a taste at levels greater

than 0.3 ppmv and a strong odor at levels greater than 0.5 ppmv. SO 2(g) is a precursor to sulfuric acid (H2SO4(aq)), an aerosol particle component that affects acid deposition, global climate, and the global ozone layer. SO2(g) is now regulated in many countries, with effective measures that lead to decrease mixing ratios.

Some sources include coal-fired power plants, automobile tailpipes, but also natural sources like volcanoes. SO2(g) is also produced chemically in the air from biologically produced dimethylsulfide (DMS(g)) and hydrogen sulfide (H2S(g)). Sulfide is removed by chemical reaction, dissolution in water, and transfer to soils and ice caps. SO2(g) is relatively soluble. Table I.1.8. summarizes the major sources and sinks of SO2(g).

Table I.1.8. Sources and Sinks of Atmospheric Sulfur Dioxide

Sources SinksOxidation of DMS(g)Volcanic emissionFossil-fuel combustion Mineral ore processingChemical manufacturing

Kinetic reaction to H2SO4(g)Dissolution in cloud drops and ocean waterTransfer to soils and ice caps

In the background troposphere, SO2(g) mixing ratios range from 10 pptv to 1 ppbv. In polluted air, they range from 1 to 30 ppbv, and in extreme cases peaks of 5ppm (Millan,M & Sanz,MJ, 1993). SO2(g) levels are usually lower indoors than outdoors. The indoor to outdoor ratio of SO2(g) is typically between 0.1:1 to 0.6:1 in buildings without indoor sources (Jones, 1999). In one study, indoor mixing ratios were found to be 30 to 57 ppbv in homes equipped with kerosene heaters or gas stoves (Leaderer et al., 1984, 1993).

Because SO2(g) is soluble, it is absorbed in the mucous membranes of the nose and respiratory tract. Sulfuric acid (H2SO4(aq)) is also soluble, but its deposition

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rate into the respiratory tract depends on the size of the particle in which it dissolves (Maroni et al., 1995). High concentrations of SO2(g) and H2SO4(aq) can harm the lungs (Islam and Ulmer, 1979). Long-term exposure to SO2(g) from coal burning is associated with impaired lung function and other respiratory ailments (Qin et al., 1993). Injury to plants is also well documented, symptoms appear as ivory to brown areas between the veins (inter-vein) and along the leaf edges. Uninjured tissue next to the veins remains green. Injury is likely to occur at mid-day on plants growing in moist soil.

Nitric OxideNitric oxide (NO(g)) is a colorless gas and a free radical. It is important

because it is a precursor to tropospheric ozone, nitric acid (HNO3(g)), and particulate nitrate (NO3

-). Whereas NO(g) does not directly affect acid deposition, nitric acid does. Whereas NO(g) does not affect climate, ozone and particulate nitrate do. Natural NO(g) reduces ozone in the upper stratosphere. Emissions of NO(g) from jets that fly in the stratosphere also reduce stratospheric ozone. Outdoor levels of NO(g) are not regulated in any country.

NO(g) is emitted by microbes in soils and plants during denitrification, and it is produced by lightning, combustion, and chemical reactions. Combustion sources include aircraft, automobiles, oil refineries, and biomass burning. The primary sink of NO(g) is the chemical reaction. Table I.1.9. summarizes the sources and sinks of NO(g).

Table I.1.9. Sources and Sinks of Atmospheric Nitric Oxide.

Sources SinksDenitrification in soils and plants Lightning Fossil-fuel combustion Biomass burningPhotolysis and kinetic reaction

Kinetic reaction Dissolution in ocean waterTransfer to soils and ice caps

A typical sea-level mixing ratio of NO(g) in the background troposphere is 5 pptv. In the upper troposphere, NO(g) mixing ratios are 20 to 60 pptv. In urban regions, NO(g) mixing ratios reach 0.1 ppmv in the early morning, but may decrease to zero by midmorning due to the reaction with ozone.

Nitric oxide has no known harmful human health effects at typical outdoor or indoor mixing ratios.

Nitrogen DioxideNitrogen dioxide (NO2(g)) is a brown gas with a strong odor. NO2(g) is an

intermediary between NO(g) emission and O3(g) formation. It is also a precursor to

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nitric acid, a component of acid deposition. Natural NO2(g), like natural NO(g), reduces ozone in the upper stratosphere. It is now regulated in many countries.

Its major source is the oxidation of NO(g). Minor sources are fossil fuel combustion and biomass burning. During combustion or burning, NO2(g) emissions are about 5 to 15 percent those of NO(g). Table I.1.10. summarizes sources and sinks of NO2(g).

Table I.1.10. Sources and Sinks of Atmospheric Nitrogen Dioxide.

Sources SinksPhotolysis and kinetic reaction Fossil-fuel combustion Biomass burning

Photolysis and kinetic reactionDissolution in ocean waterTransfer to soils and ice caps

Indoor sources of NO2(g) include gas appliances, kerosene heaters, wood-burning stoves, and cigarettes. Sinks of NO2(g) include photolysis, chemical reaction, dissolution into ocean water, and transfer to soils and ice caps. NO2(g) is relatively insoluble in water.

Mixing ratios of NO2(g) near sea level in the free troposphere range from 20 to 50 pptv. In the upper troposphere, mixing ratios are 30 to 70 pptv. In urban regions, they range from 0.1 to 0.25 ppmv. Outdoors, NO2(g) is more prevalent during early morning than during midday or afternoon because sunlight breaks down most NO2(g) past midmorning, normally opposite to ozone. In homes with gas-cooking stoves or unvented gas space heaters, weekly average NO2(g) mixing ratios can range from 21 to 50 ppbv, although peak mixing ratios may reach 400-1,000 ppbv (Spengler, 1993; Jones et al., 1999).

Although exposure to high mixing ratios of NO2(g) harms the lungs and increases respiratory infections (Frampton et al., 1991), epidemiological evidence indicates that exposure to typical mixing ratios of NO2(g) has little effect on the general population. Children and asthmatics are more susceptible to illness associated with high NO2(g) mixing ratios than are adults (Li et al., 1994). Pilotto et al. (1997) found that levels of NO2(g) greater than 80 ppbv resulted in increased reports of sore throats, colds, and absences from school. Goldstein et al. (1988) found that exposure to 300 to 800 ppbv NO2(g) in kitchens reduced lung capacity by about 10 percent. NO2(g) may trigger asthma by damaging or irritating and sensitizing the lungs, making people more susceptible to allergic response to indoor allergens (Jones, 1999). At mixing ratios unrealistic under normal indoor or outdoor conditions, NO2(g) can result in acute bronchitis (25 to 100 ppmv) or death (150 ppmv). In plants, acute symptoms appear as ivory to brown areas between the veins (inter-vein) and along the leaf edges. Uninjured tissue next to the veins remains green and damage occurs at night. Nitrous oxide also causes yellowing of leaf margins and internervial chlorosis.

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LeadLead (Pb(s)) is a grey-white, solid heavy metal with a low melting point that is

present in air pollution as an aerosol particle component. It was first regulated as a criteria air pollutant in the United States in 1976. Many countries now regulate the emission and outdoor concentration of lead.

Lead is emitted during combustion of leaded fuel, manufacture of lead-acid batteries, crushing of lead ore, condensation of lead fumes from lead-ore smelting, solid-waste disposal, uplift of lead-containing soils, and crustal weathering of lead ore. Between the 1920s and the 1970s, the largest source of atmospheric lead was automobile combustion. Table I.1.11 summarizes the sources and sinks of atmospheric lead.

Table I.1.11. Sources and Sinks of Atmospheric Lead.

Sources SinksLeaded-fuel combustion Lead-acid battery manufacturingLead-ore crushing and smeltingDust from soils contaminated with lead-based paint Solid-waste disposalCrustal physical weathering

Deposition to soils, ice caps and oceans Inhalation

In December 1921, Thomas J. Midgley Jr. (1889-1944) discovered that tetraethyl lead was a useful fuel additive for reducing engine knock, increasing octane levels, and increasing engine power and efficiency in automobiles. Midgley experienced lead poisoning. In 1925, the U.S. head of the Public Health Service put together a committee to study the health effects of tetraethyl lead. Moreover, it was argued that because no regulatory precedent existed, the committee would have to find striking evidence of serious and immediate harm for action to be taken against lead (Kovarik, 1999). Based on measurements that showed lead contents in faecal pellets of typical drivers and garage workers lower than those of lead-industry workers, and based on the observations that drivers and garage workers had not experienced direct lead poisoning, they concluded that there were "no grounds for prohibiting the use of ethyl gasoline" (U.S. Public Health Service, 1925). He did caution that further studies should be carried out (U.S. Public Health Service, 1925). Despite the caution, more studies were not carried out for thirty years, and effective opposition to the use of leaded gasoline ended. By the mid-1930s, 90 percent of U.S. gasoline was leaded. Industrial backing of lead became so strong in 1936, that only in 1959 did the U.S. Public Health Service reinvestigate the issue of tetraethyl lead. At that time, they found it "regrettable that the investigations recommended by the Surgeon General's

20

Committee in 1926 were not carried out by the Public Health Service" (U.S. Public Health Service, 1959). Despite the concern, tetraethyl lead was not regulated as a pollutant in the United States until 1976. In 1975, the catalytic converter, which reduced emission of carbon monoxide, hydrocarbons, and eventually oxides of nitrogen from cars, was invented. Because lead deactivates the catalyst in the catalytic converter, cars using catalytic converters could run only on unleaded fuels. Thus, the required use of the catalytic converter in new cars inadvertently provided a convenient method to phase out the use of lead. The regulation of lead as a criteria air pollutant in the United States in 1976 due to its health effects also hastened the phase out of lead as a gasoline additive. Between 1970 and 1997, total lead emissions in the United States decreased from 219,000 to 4,000 short tons per year. Since the 1980s, leaded gasoline has been phased out in many countries, although it is still an additive to gasoline in several others.

Ambient concentrations of lead between 1988 and 1997 decreased from about 0.17 to 0.06 g m-3, or by 67 percent (U.S. EPA, 1998). The highest concentrations of lead are now found near lead-ore smelters and battery manufacturing plants in the States. But developing countries still have high harmful concentrations.

Health effects of lead were known by the early Romans. Lead accumulates in bones, soft tissue, and blood. It can affect the kidneys, liver, and the nervous system. Severe effects of lead poisoning include mental retardation, behavior disorders, and neurological impairment. A disease associated with lead accumulation is plumbism. Symptoms at various stages include abdominal pains, a black line near the base of the gums, paralysis, loss of nerve function, dizziness, blindness, deafness, coma, and death. Low doses of lead have been linked to nervous system damage in fetuses and young children, resulting in learning deficits and low IQs. Lead may also contribute to high blood pressure and heart disease (U.S. EPA, 1998). Many plant species accumulate lead up to very high concentrations, and can be used for bioremediation. On the other hand, edible plants that accumulate lead can be harmful for humans.

AmmoniaAmmonia is a colorless alkaline gas (NH3(g)). It is a precursor to the

formation of secondary particles in the atmosphere. Gaseous ammonia reacts chemically with other gases and particles which can produce particulate matter (PM) such as ammonium nitrate (NH4NO3) or ammonium sulfate ((NH4)2SO4) with diameters less than 2.5 µm (PM2.5) (CAC, 1995). These fine particles cause the greatest concern for human health. In low concentrations, it has a penetrating pungent sharp odor. In high concentrations, it causes a smothering sensation when inhaled. They can penetrate deep into the lungs where they may cause irritation and exacerbate lung disease. Particulate matter and ammonia are also linked to air quality issues such as reduced visibility.

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Hydrogen FluorineHydrogen fluoride (HFl (g)) is a colorless gas or fuming liquid (Hydrofluoric

acid) and it is strongly irritant and very corrosive. It is used extensively in industry, especially as an intermediate in the manufacture of most fluoride-containing products. The odor detection limit is around 30-130 μg/m3. Humans are reasonable tolerant, but it is the most toxic pollutant where plants are concerned and it may also have profound effects on grazing animals if excessive amounts contaminate their forage (Weinstein and Davison, 2004). In plants visible injury is very characteristic as marginal chlorosis that can evolve to necrosis as concentric bands.

I.1.2.4. Aerosol Particles in Smog and the Global Environment

Although most regulations of air pollution focus on gases, aerosol particles cause more visibility degradation and possibly more health problems than do gases. Particles smaller than 2.5 m in diameter cause the most severe health problems. Particles enter the atmosphere by emissions and nucleation. In the air, their number concentrations and sizes change by coagulation, condensation, chemistry, water uptake, rainout, sedimentation, dry deposition, and transport. Particle concentration, size, and morphology affect the irradiative energy balance in urban air and in the global atmosphere.

Size DistributionsAerosol and hydrometeor particles are characterized by their size distribution

and composition. A size distribution is the variation of concentration (i.e., number, surface area, volume, or mass of particles per unit volume of air) with size. Table I.1.12 compares typical diameters, number concentrations, and mass concentrations of gases, aerosol particles, and hydrometeor particles under lower tropospheric conditions. The table indicates that the number and mass concentrations of gas molecules are much greater than are those of particles. The number concentration of aerosol particles decreases with increasing particle size. The number concentrations of hydrometeor particles are typically less than are those of aerosol particles, but the mass concentrations of hydrometeor particles are always greater than those of aerosol particles.

The aerosol particle size distributions can be divided into modes, which are region of the size spectrum (in diameter space) in which distinct peaks in concentration occur.

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Table I.1.12. Characteristics of Gases, Aerosol Particles, and Hydrometeor Particles

Typical diameter (m)

Number Concentration(molecules or particles

cm-3)

Mass Concentration

(g m-3)Gas moleculesAerosol particlesSmallMediumLarge

Hydrometeor particlesFog dropsCloud dropsDrizzleRaindrops

0.0005

<0.20.2-2.0

>2.010-2010-200

200-1,0001,000-8,000

2.45 x 1019

103 - 106

1 – 104

< 1 – 10

1 – 5001 – 10000.01 – 1

0.001 – 0.01

1.2 x 109

< 1< 250

104 – 106

104 – 107

105 - 107

105 - 107

Aerosol particle distributions with the 1, 2, 3, or 4 modes are called unimodal, bimodal, trimodal, or quadrimodal, respectively. Such modes may include a nucleation mode, two sub-accumulation modes, and a coarse mode. The nucleation mode (mean diameters less than 0.1 (m) contains small emitted particles or newly nucleated particles (particles formed directly from the gas phase). Small nucleated or emitted particles increase in size by coagulation (collision and coalescence of particles) and growth (condensation of gases onto particles). Only a few gases, such as sulfuric acid, water, and some heavy organic gases, among others, condense onto particles. Molecular oxygen and nitrogen, which make up the bulk of the gas in the air, do not.

Growth and coagulation move nucleation mode particles into the accumulation mode, where diameters are 0.1 to 2 m. Some of these particles are removed by rain, but they are too light to fall out of the air by sedimentation (dropping by their own weight against the force of drag). The accumulation mode sometimes consists of two sub-modes with mean diameters near 0.2 m and 0.5 to 0.7 m (Hering and Friedlander, 1982; John et al., 1989), possibly corresponding to newer and aged particles, respectively. The accumulation mode is important for two reasons. First, accumulation mode particles are likely to affect health by penetrating deep into the lungs. Second, accumulation mode particles are close in size to the peak wavelengths of visible light and, as a result, affect visibility. Particles in the nucleation and accumulation modes together are fine particles.

The coarse mode consists of particles larger than 2 m in diameter. These particles originate from windblown dust, sea spray, volcanoes, plants, and other sources. Coarse mode particles are generally heavy enough to sediment out rapidly within hours to days. The emission sources and deposition sinks of fine particles differ

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from those of coarse mode particles. Fine particles usually do not grow by condensation to much larger than 1 m, indicating that coarse mode particles originate primarily from emissions.

Sources and Compositions of New ParticlesNew aerosol particles originate from two sources: emissions and nucleation.

Emitted particles are called primary particles. Particles produced by homogenous nucleation, a gas-to-particle conversion process, are called secondary particles. Primary particles may originate from point, mobile, or area sources.

The aerosol particle emission sources may be natural or anthropogenic. Natural emission processes include volcanic eruptions, soil-dust uplift, sea-spray uplift, natural biomass burning fires, and biological material release. Major anthropogenic sources include fugitive dust emissions (dust from road paving, passenger and agricultural vehicles, and building construction/demolition), fossil-fuel combustion, anthropogenic biomass burning, and industrial emissions. Table I.1.13 summarizes the natural and anthropogenic sources of the major components present in aerosol particles. These sources are discussed in more detail shortly.

Table I.1.13. Principal Sources of Major Components of Aerosol-Particles

Sea-spray

Soil-Dust Vulcanic Biomass

Burning

Fossil-Fuel Combustion for Transportation

and Energy

Fossil-Fuel and Metal

Combustion for

Industrial Process

Black carbon (C)Organic matter (C,H,0,N)Ammonium (NH4

+)Sodium (Na+)Calcium (Ca2+)Magnesium (Mg2+)Potassium (K+)Sulfate (SO4

2-)Nitrate (NO3

-)Chloride (Cl-)Silicon (Si)Aluminum (Al)Iron (Fe)

X

XXXXX

X

XXXXXXX

XXXX

XX

XXXXX

XXXX

XXXXXXXXXX

X

XXX

X

XXX

XXXXXXXXXXXXX

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Aside from emissions, nucleation is the only source of new particles in the air. Nucleation is a process by which gas molecules aggregate to form clusters. If the radius of the cluster reaches a critical size, the cluster becomes stable and can grow further. Nucleation is either homogeneous or heterogeneous. Homogeneous nucleation occurs when gases nucleate without the aid of an existing surface. Thus, homogeneous nucleation is a source of new particles. Heterogeneous nucleation occurs when gases nucleate on a pre-existing surface. Thus, it does not result in new particles. Homogeneous or heterogeneous nucleation must occur before a particle can grow by condensation, a process discussed shortly.

The most important homogeneous nucleation process in the air is binary nucleation of sulfuric acid with water. Homogeneously nucleated sulfuric acid-water particles are typically 3 to 20 nm in diameter. In the remote atmosphere (e.g., over the ocean), homogenous nucleation events can produce more than 104 particles cm-3 in this size range over a short period. Homogenous nucleation of water vapor does not occur under typical atmospheric conditions. Water vapor nucleation is always heterogeneous. Indeed, all cloud drops in the atmosphere consist of water that has condensed onto aerosol particles following the heterogeneous nucleation of these particles. Aerosol particles that become cloud drops following heterogeneous nucleation by and condensation of water vapor are called cloud condensation nuclei (CCN).

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I.2. WATER POLLUTANTS

I.2.1. TYPES OF WATER POLLUTANTS

Mihaela Carmen CHEREGI

For years, the quality of drinking water has been an important factor in determining the human welfare. Frequently, waterborne diseases that have decimated the population of many cities were caused by fecal pollution. Water pollution by natural sources has caused great hardship for people forced to drink it or use it for irrigation.

Bacterial and viral diseases carried by infectious agents in drinking waters have in general been controlled, and drinking waters in the technologically advanced countries are now free of the disease-causing agents that were common water contaminants only a few decades earlier.

Nowadays, the growth of the industrial and agricultural modern techniques has as result the obtaining of new synthetic chemicals. Many of these chemicals have contaminated water supplies. There are two types of water chemical contamination, one is the permanent contamination that includes wastes from industrial production, municipal wastes, fertilizers and pesticides runoff from agricultural lands and the other is the occasional contamination that includes transport accidents, leakage of toxic or radioactive substances. Also, there is a threat to groundwater from waste chemical dumps and landfills, storage lagoons, treating ponds, and other facilities.

It is clear that water pollution must be a concern of every citizen. Understanding the sources, interactions, and effects of water pollutants is essential for controlling and monitoring the contaminants in an environmentally safe and economically acceptable manner.

Analytical methods were developed to document the presence of pollutant in the environment and to describe the extent to which an area was contaminated. The pollutants monitoring in the environment continues to be of interest to today’s scientists, who desire to understand the long-term, health effects of chronic exposure to low concentrations of pollutants. As instrumental detection limits improve and as newer detection techniques, such as liquid chromatography/mass spectrometry (LC/MS), become more widely used, polar environmental contaminants, for example water disinfection by products, degradation products of pesticides, pharmaceutical compounds, are being discovered, identified and quantified.

Water pollutants can be classified among general categories, as Table I.2.1 shows. An enormous number of publications related to this subject come out each year and it is impossible to present it all in this chapter. Some journals and books dealing with water pollution are listed in the Reference section at the end of this chapter.

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Table I.2.1 Types of water pollutants.

Class of pollutant SignificanceTrace elementsHeavy metalsMetalloids and organically-bound metalsInorganic pollutantsAcidity, alkalinity, salinityAlgal nutrients and bacterial toxinsBio- and chemical oxygen demandTrace organic pollutantsPolychlorinated biphenyls PesticidesPetroleum wastesSewage, human and animal wasteRadionuclidesPathogens DetergentsChemical carcinogensSedimentsTaste, odor, color

Health, aquatic biota, toxicityHealth, aquatic biota, toxicityMetal transportToxicity, aquatic biotaWater quality, aquatic lifeEutrophication, toxicity, aquatic biotaWater quality, oxygen levelsToxicityPossible biological effectsToxicity, aquatic biota, wildlifeEffects on wildlife, estheticsWater quality, oxygen levelToxicityHealth effectsEutrophication, wildlife, estheticsIncidence of cancerWater quality, aqua biota, wildlifeEsthetics

I.2.2. METALS (Cadmium, Lead, Mercury, etc.) (Meyers, R.A. & Dittrich, D.K., 1999)

Andrei Florin DǍNEŢ

I.2.2.1. Metal Toxicity

The greatest concerns in heavy metal usage and releases into the environment are industrial sources, agricultural usage, food products and chemical wastes. Metal toxicity is modified by various environmental factors, such as light, temperature, humidity, and pH (e.g. in soil and water). The most important factors that influence the metabolism and effects of metals are: age, sex, diet, species and dose/duration of exposure.

The toxic effects of metals could be very different: renal toxicity, neurotoxicity, genotoxicity, developmental toxicity, etc. (Chang, L.W., 1996)

27

CadmiumCadmium causes toxic injury to the renal, pulmonary, skeletal, testicular and

nervous system (Chang, L.W., 1981). The toxicity of cadmium may be explained by the production of metallothionein. The breakdown of the Cd-metallothionein complex within cells releases free cadmium within cells for the induction of cell damage. Hemorrhagic lesions are hallmarks of cadmium toxicity in the testis, lung and neonatal brains (Chang, L.W., 1981; Murphy, V.A., 1996).

MercuryMercury vapors and organomercury (alkyl mercury) enter the central nervous

system (by crossing the blood-brain barrier) very readily and are considered highly neurotoxic. The neurotoxic mechanisms of mercury are extremely complex. Combinations of the following mechanism of actions occur: (a) inhibition of protein and macromolecule (e.g. RNA) syntheses; (b) modified post-translation phosphorylation; (c) defective calcium homeostasis and ion flux; (d) abnormal neurotransmitter homeostasis; (e) oxidative injury; (f) cytoskeletal disaggregations; (g) mitochondrial dysfunction (Chang, L.W. & Verity, M.A., 1985; Verity, M.A., 1996). Since the outbreak of methylmercury poisoning in Japan (Minamata), methyl mercury poisoning is also known as Minamata disease.Inorganic mercury ions (Hg2+) are not a potent neurotoxic substance because they do not cross the blood-brain barrier effectively. Inorganic mercury salts, however, are very nephrotoxic, producing necrotizing damage to the renal proximal tubules (Chang, L.W., 1979).

LeadOne of the best known effects of inorganic lead is its impact on hemoglobin

synthesis resulting in stippling of the erythrocytes and anemia. Two mitochondrial enzymes are inhibited leading to reduced insertion of Fe2+ into the heme and the synthesis of protoporphyrin (Hammond, P.B. & Bililes, R.P., 1980).

Chronic lead exposures of most concern are for children who are exposed to low levels of lead via contaminated drinking water, lead-containing paint, or lead-containing environment. Significant neurobehavioral changes and learning disabilities are reported in animals and children following lead exposure at a young age. The mechanisms of action for lead neurotoxicity are multifaceted including alteration in calcium homeostasis, ion channels and neurotransmitters, signal transduction and the calcium messenger system (Cory-Slechta, D.A. & Pounds, J.G., 1995). Organolead, as an additive to gasoline, was a serious environmental concern (Seawright, A.A. et al, 1984).

AluminumAluminum is considered a neurotoxic metal inducing significant biochemical

changes and cytoskeletal neuropathology. Motor neurons, anterior thalamic nuclei and

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neurons of the para subiculum are especially sensitive to aluminum. The mechanistic base of aluminum neurotoxicity involves alterations in calcium homeostasis, energy metabolism, RNA synthesis, etc. (Lukiw, W.J. & McLachlan, D.R., 1995).

ArsenicArsenic is a general cytotoxicant causing injury to most cells and organ

systems. Arsenic chelates with α-lipoic acid which is an essential cofactor for pyruvate dehidrogenase, an enzyme critical in mitochondrial production of ATP. Arsenic forms also an oxyanion, which mimics phosphate oxyanion and thus disrupts a variety of biological processes requiring phosphate, including ATP synthesis (Clarkson, T.W., 1991).

ManganeseAlthough manganese is an essential trace element in the biological systems,

overexposure to manganese results in toxicity. In chronic situations, the neurological signs of manganism resemble Parkinson’ disease and dystonia (Chu, N.S et al, 1995). The toxicity of manganese is related to biological transformation of Mn2+ to Mn3+ with autoxidation of dopamine and the production of cytotoxic free radicals (Chu, N.S et al, 1995).

I.2.2.2. Biotransformation of metals

It is assumed that biometabolism of inorganic species are, practically, in all cases enzymatically mediated (Ochiai, Ei-O, 1987). For carcinogenic metals, it is assumed that Phase I enzymes (including P450 isoenzymes) are involved; if a metal is an anticancer agent, Phase II enzymes (including the glutathione-S-transferase) play a role. Current research is devoted to the role of metals as precursors of active oxygen and the effect on lipid peroxidation (Wetterhahn, E.K. & Dudek, E.J., 1996).

MercuryMetallic, liquid inorganic mercury has a high vapor pressure and is quite

soluble in lipids. The lungs are the most important area for absorption. After absorption, the lungs retains as much as 80%, in contrast with gastrointestinal absorption, which retains less than 0.01%. The free mercury, which circulates in the bloodstream, crosses the blood-brain barrier easily. Within a minute, the free mercury oxidizes to Hg2+ and is no longer strongly lipid soluble. This oxidation is done by catalase in the biological system (Clarkson, T. et al, 1984). Microorganisms transform free mercury to the +1 or +2 state; these microorganisms also methylate mercury to monomethyl mercury chloride or dimethylmercury. These lipid soluble compounds ingested by fish are stored in the liver (Von Berg, R. & Greenwood, M.R. 1991).

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ArsenicWithin biological systems, arsenic cycles easily between As3+ and As5+. In a

number of systems, arsenic is methylated to mono-, di- and even to the trimethylated metabolite. All postulations invoke the interaction with GSH-S-t and hence GSH, and the cytosolic enzymes requiring methyl donors, S-adenosylmethionine (ADO MET), metylcobalamin (vitamin B12) and Mg2+ (Styblo, M. et al, 1995). Microorganisms including bacteria, fungi, yeasts, molds and algae have common bio-pathways.

NickelMuch effort has been made to evaluate the carcinogenicity of nickel by

directly implanting the nickel compound in specific organ and tissue. Nickel and its compounds are carcinogenic agents. Currently many investigators are working on the carcinogenicity of nickel compounds (Kasprzak, K.S. et al, 1987; Hass, B.S. et al, 1996).

ChromiumOf all the inorganic compounds, chromium as Cr6+ is most active as a carcinogen and mutagen. This ion is genotoxic in almost every system tested. Cr6+ is also considered a human carcinogen by the World Health Organization.

CopperCopper as Cu2+ initiates lipid peroxidation with high, low or very low-density human lipoprotein (Kontush, A., 1996). During this reaction, copper is rapidly reduced to Cu+.

TinMany tin compounds are neurotoxins, especially the alkyltin compounds

(Chang, L.W., 1995).

I.2.3. METALLOIDS AND ORGANOMETALLIC COMPOUNDS

Mihaela Carmen CHEREGI

I.2.3.1. Metalloids

The most significant water pollutant metalloid is arsenic, a toxic element that has been the chemical villain of more than a few murder plots. Acute arsenic poising can result from the ingestion of more than about 100 mg of it. Excessive exposure to this element can lead to health effects on the digestive and central nervous system,

30

heart and kidneys and some of its compounds may cause cancer and genetic damage. Arsenic is also toxic for aquatic live. However, the impact on human health and the environment depend on the form and bioavailability of this metalloid.

Arsenic has been a politically charged issue the last three years. Unlike many other contaminants that are anthropogenic, arsenic contamination of waters generally comes from natural sources, through the erosion of rocks, minerals and soils. The arsenic concentration in the Earth’s crust is at a level of 2–5 ppm. The combustion of fossil fuels (e.g. coal) introduces large quantities of arsenic into the environment, much of it reaching natural waters. Arsenic occurs with phosphate minerals and enters into the environmental along with some phosphorous compounds.

It is used in the manufacture of wood preservatives, glass and non-ferrous alloys. The use in agricultural products (pesticides) is banned in almost all-western countries. Arsenic is also used in bronzing and pyrotechnics. Another source of arsenic is mine tailing. Arsenic produced as a by-product of copper, gold, and lead refining exceeds the commercial demand for arsenic, and it accumulates as waste material.

The most important compounds are white arsenic, the sulfide Paris green (copper arsenate), calcium arsenate and lead arsenate, the last three being used as agricultural insecticides.

Like mercury, arsenic may be converted to more mobile and toxic methyl derivatives by bacteria, following the reactions:

H3AsO4 + 2H+ + 2e- H3AsO3 + H2O

H3AsO3 CH3AsO(OH)2

Methylarsinic acid

CH3AsO(OH)2 (CH3)2AsO(OH) Dimethylarsinic acid

(CH3)2AsO(OH) + 4H+ + 4e- (CH3)2AsH + 2H2O

International agencies of environmental protection have conducted researches on arsenic (occurrence, health effects, bioavailability) and indented to lower the existing standard in drinking water of 50 g/L to a level that would better protect human health. In January 2001, the U.S. EPA proposed to lower the standard to 10 g/L, this rule became effective on February 2002 and drinking water systems must comply with this new standard by January 2006.

On the non-political front, arsenic research issues that have become important are determining individual species of this metalloid and their occurrence in water, food, and biological sample. Different arsenic species have different toxicity and

31

methylcobalamin

methylcobalamin

chemical behavior in aquatic systems, therefore, it is important to be able to identify and quantify them.

I.2.3.2. Organically Bound Metals and Metalloids

In aquatic systems, two major types of metal-organic interactions are considered:

a. Complexation, usually chelation when organic ligand is involved. A definition of complexation in natural water or wastewater is: a process in which a species that is present reversibly dissociates to a metal ion and an organic ligand as a function of pH:

ML + 2H+ M2+ + H2Lwhere M2+ is a metal ion and H2L is the protonated form of the ligand L-2.

b. Metals bonded to organic entities by way of carbon atom that are non-dissociated at lower pH or large dilution. The organic component and the particular oxidation state of the metal involved may not be stable apart from the organometallic compounds.

A simple way to classify these species from their toxicology point of view may be:

1. With alkyl group such as ethyl in tetraethyl lead, Pb(C2H5)4;2. Carbonyls, some of them are quite volatile and toxic, having carbon

monoxide bonded to metals :C O:3. With an organic group donating electron such as ethylene or benzene.The most prominent of the compounds outlined above are the arene carbonyl

species in which the metal ion is bonded to both an aryl entity such as benzene and to several carbon monoxide molecules.

A large number of compounds exist that have at least one bond between the metal and a C atom on an organic group, as well as other covalent ionic bonds between the metal and atoms other than carbon. Because they have at least one metal – carbon bond, as well as properties, uses, and toxicological effects typical of organometallic compounds, it is useful to consider such compound along with organometallic compounds. Examples are monomethylmercury chloride in which the organometallic CH3Hg+ ion is ionically bonded to the chloride anion; phenyldichloroarsine, C6H5AsCl2, in which a phenyl group is covalently bonded to arsenic through an As–C bond, and two Cl- anions are also covalently bonded to As.

Another type consists of organic groups bonded to a metal atom through atoms other than carbon. These compounds do not meet the strict definition; such compounds can be classified as organometallics for discussion of their toxicology and aspects of chemistry. An example is isopropyl titanate (or titanium isopropylate), Ti( i–C3H7)4.

32

The interaction of trace metals with organic compounds in natural waters is too vast, it may be noted that metal–organic interactions may involve organic species of both pollutants (such as EDTA) and natural (such as fulvic acid) origin. These interactions are influenced by redox equilibrium, formation–dissolution of precipitates; colloid formation and stability; acid–base equilibrium; and microorganisms–mediated reaction in water. Metal–organic interactions may increase or decrease the toxicity of metals in aquatic ecosystems, and they have a strong influence on the growth of algae in waters.

Organotin compounds are generally man-made chemicals with a global production on the order of 40,000 tones/year. Of all the metals, tin has the greatest number of organometallic compounds in commercial use.

In the past, one of the main sources of release into the marine environment was triphenyltins and tributyltins, which had been used in paints for the ships and boats. Other sources of organotin release included the industries that they are used in, particularly the chemical industry, and through their applications in fungicides, acarides, disinfectants, antifouling paint, stabilizers to lessen the effects of heat and light in PVC plastics, catalysts, precursors for formation of films of SnO2 on glass, and wood preservative products. Tributyltin chloride compounds (TBT) have bactericidal, fungicidal, and insecticidal properties and have particular environmental significance because of their use as industrial biocides. Tributyltin hydroxide, naphthenate, bis (tributyltin) oxide, and tris (tributylstannyl) phosphate are also used as biocides. Antifungal TBT compounds have been used as slimicides in cooling tower water.

The toxicity of organotins generally follows the order: trialkyl > dialkyl > monoalkyl but the dialkyl form is much more neurotoxic, with an effect in brain cells from as low as 30 ppb. European countries have proposed banning the use of PVC pipe to transport potable water, due to the leaching of organotin from PVC plastic products (dibutyltin is used as a heat stabilizer in PVC pipe). In addition to synthetic organotins compounds, methylated tin species can be produced biologically in the environment.

Excessive exposure to some organic tin compounds may cause adverse health effects on brain, eye, immune system, lung, skin and the unborn child, and may cause cancer. Most local environmental concerns arise from organotin pollution in marine waters. TBT is very toxic for algae, mollusks, crustaceans and fish. It has been identified as an endocrine disrupting substance with observable effects in gastropod mollusks and suggested effects in marine mammals. Also, it impairs the immune system of organisms and lead to shellfish developing shell malformations. Triphenyltin may have similar effects.

Because of such concerns, several countries, including U.S., England and France, prohibited TBT application on vessel smaller than 25 meters in length during the 1980s. In 1998 the International Marine Organization agreed to ban organotin antifouling paints on all ships by 2003.

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I.2.4 ANIONIC INORGANIC SPECIES

Tomas ALEXANDERSSON

In this subchapter the most important inorganic anionic species, which have an impact on the environment, are presented. These species are chosen since they are either direct toxic or they have an indirect effect in the area where they are released. Besides the environmental effect, information about the most common use and sources are also included.

I.2.4.1. Chloride

Chloride is the ionic form of elemental chlorine. It occurs naturally in a wide range of concentrations in waters. Upland reservoirs of water generally contain low concentrations of chlorides whereas the concentration increases in rivers and groundwater. The highest concentration is found in the sea due to the partial evaporation of water.

Chloride is spread into the environment from several different sources. In the industry hydrochloride is an important chemical and it is used in many different areas such as cleaning of metal surfaces in order to remove the oxide layer and in the production of different organic chemicals. After use, the chlorides are disposed of in the wastewater. In areas with cold climate, sodium chloride is used for preventing a slippery road surface. During its use, the chloride compound is spread on the road and from there it is transported into the environment with rainfall and snowfall. Another chloride salt, calcium chloride, is used during the summer to prevent gravel roads from giving off dust. Chloride is also spread into the environment with wastewater from households. This chloride originates from the food that we consume and is excreted from the human body in particularly the urine.

Reasonable concentrations of chloride are not harmful to humans. If there is a limit for chlorides it is usually set by the salty character it gives to the water at a concentration of 250 mg/L. The type of flora and fauna that develops in natural waters is depending on the composition of the water. If this is changed from low ionic to high ionic due to the discharge of high strength wastewater the composition of organisms and plants will also change.

I.2.4.2. Fluoride

Fluoride is the most common halogen and large amounts can be found in the minerals apatite (Ca5(F, OH)(PO4)3 (the ions F and OH can substitute each other)) and fluorspar (CaF2). The exact composition of the type of mineral in the ground and its

34

distribution influences the natural background concentration of fluoride in the groundwater. Normally this range is between 0 and 0.2 ppm. Fluoride can also be found in the air but this is usually restricted to areas affected by human activities. Unaffected air normally does not contain measurable concentrations of fluoride.

Fluoride is an important component in the production of aluminum. The raw material is aluminum oxide (Al2O3), which is dissolved in cryolite (Na3AlF6) to form an electrolyte. Aluminum is then formed by the reduction of aluminum ions. During this process fluorides escape from the molten to the gas phase and can be spread in the immediate area around the aluminum production plant. Introduction of gas cleaning by electrostatic filters or wet scrubbers have reduced the amount of fluorides released into the air. However, the cleaning of the gas does not solve the problem but instead transfers it into a water problem instead. Many of the industries that discharge fluorides in the air also release fluorides by water pollution. The largest sources for fluoride pollution are phosphate fertilizer producer and metallurgic industry like aluminum producers. Another major source of fluorides is the domestic sewage. The reason for this is the positive effect that fluorides have on the strength of the dental enamel and its ability to prevent the formation of caries. Therefore, in some areas fluoride is added to the drinking water in order to improve the dental status. It is however, important not to be exposed to too much fluoride. It was found that in areas were the groundwater contained more than 1 mg/L of fluoride people suffered from mottled enamel or dental fluorosis.

What effect enhanced concentrations of fluorides could have on freshwater and marine organisms is not completely examined. It is however, reasonable to conclude that marine organisms, which normally exist in an environment with a small concentration of fluoride (around 0.6 ppm in the sea), would not be affected by a modest release of fluoride. The situation for freshwater organisms is a little bit different. They live in an environment almost total fluoride free and it is possible that these organisms could be more affected by fluoride containing effluent. More research is required in this area since little is known about the impact from fluoride on both marine and freshwater organisms.

The situation for fluorides in the air is a little bit different. One conclusion from the US Department of Agriculture is that fluoride has done more damage to livestock than any other pollutant. Fluoride released to the air from industries is spread in the nearest surroundings and is accumulated in the plants. This fluoride enriched forage can be seriously toxic when cattle ingest it. Little is known about the long-term effects of fluoride exposure and it is important to gather more information in this area especially since fluoride accumulates in the food chain.

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I.2.4.3. Nitrate and Nitrite

These are very important ions since they contain nitrogen, which is vital for all organisms both plants and animals. Both nitrate and nitrite are also part of the natural nitrogen cycle (Figure I.2.1.), which explains the transformations between different nitrogen compounds.

Nitrogen is reduced to ammonia by nitrogen-fixing bacteria. Ammonia is also produced during thunderstorms by the lightning. The ammonia is taken up by plants and is used for the production of vital molecules. Ammonia could also be consumed by nitrifying bacteria, which in two steps transform ammonia to nitrate via nitrite. Plants can also use nitrate as a source of nitrogen in order to produce new plant material. Animals and humans utilize the nitrogen in the plants as material for, among other things, protein synthesis. When oxygen is absent some bacteria have the ability to use nitrate as an electron acceptor, which then will be reduced to nitrogen. Microorganisms decompose dead animals and plants and during this process the bound nitrogen is released as ammonia.

Organic matter

Ammonia

Nitrite

Nitrate

Nitrogen

Assimilation

Decomposition

Oxidation

Reduction Oxidation

Assimilation

Fixation

Figure I.2.1. Nitrogen cycle.

Both nitrite and nitrate could contribute to the eutrophication if nitrogen is a limiting factor. This would lead to production of organic matter, which when it is decomposed would consume oxygen. If the concentration of organic matter is high, oxygen free areas in the water system could develop severe effects on the water living organisms. Nitrite itself is also toxic towards fish.

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When hemoglobin is exposed to nitrite it is oxidized to methemoglobin. This change leads to a loss of the protein ability to bind to oxygen, which is very severe. Such a situation could occur when there is nitrate in the drinking water and it is very dangerous for infants and herbivores especially ruminants. All of these have a high number of nitrate reducing bacteria in their digestive system.

I.2.4.4. Sulfate and Sulfide

The sulfate ion is the second most common anionic ion in natural water after chloride. This ion has a laxative effect and usually there is a sulfate limit for drinking water. In a similar manner as the nitrogen, sulfate can be transformed into different oxidations states according to the sulfur cycle, which is a little bit more complex (Figure I.2.2.). Most of these conversions involve microorganisms or higher organisms in some way although the oxidation of hydrogen sulfide occurs rapidly at neutral and aerobic conditions. Sulfate, under anaerobic conditions, can be reduced to sulfide ion by microorganisms, which in the form of hydrogen sulfide has a very unpleasant smell of rotten eggs. It is a toxic gas and just a few breaths of hydrogen sulfide in a high concentration are sufficient to cause death. It could be produced in the sewer system were anaerobic conditions prevail in the water phase. Some of the hydrogen sulfide is released to the gas phase were it is dissolved in moisture on the sewer walls. Another type of organisms oxidizes the sulfide under the production of sulfuric acid, which causes corrosion of the sewer system. Sulfur is also needed for growth of plants and animals since there are e.g. proteins that contain sulfur. Plants normally fulfill this need by taking up sulfate.

Organic sulphur

Hydrogen sulphide

Sulphur

Sulphate

Sulphur

Assimilation

Desulphurising

Oxidation

OxidationPhototrophicOxidation

Reduction

Reduction

PhototrophicOxidation

Figure I.2.2. Sulfur cycle

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I.2.4.5. Cyanide

The cyanide ion has an electrical charge of minus one and is made up of one carbon atom and one nitrogen atom. It exists naturally in e.g. cassava and in bitter almond. The cyanide is very toxic. An excess concentration of 200 micrograms per liter is toxic to most species of fish. If cyanide enters the human body it binds to hemoglobin and prevents it from taking up oxygen. When this happens the skin develops a blue color and the condition is called cyanosis. Prolonged exposure to low concentrations of cyanide may lead to breathing difficulties and enlargement of the thyroid gland.

Cyanide forms easily a cyanic-complex with some metal ions and this property is used in concentration of gold. In this process the ore is leached by an aqueous solution of cyanide with a high pH to prevent formation of hydrogen cyanide. The gold is dissolved into the solution and further processing of the liquid results in solid gold. Cyanide is also used in other types of industries like metallurgy, chemical production, plastic production and electroplating.

There have occurred accidents with release of leaching water with high concentration of cyanide into the environment. In January 2000 a dam filled with tailings ruptured in Northwest Romania. It was estimated that around 100 tons of cyanide were released into the Sãsar river, which then were further transported into Somes/Szamos, Tisa/Tisza - Danube river system. This accident led to serious damages to the ecosystem in several of the East European countries.

I.2.4.6. Phosphate

The term phosphate is used for the different salts of phosphoric acid that contain the ions PO4

3-, HPO42- and H2PO4

-. Phosphate is essential to all living organisms and is used as a component in several cell components as the DNA and coenzymes. It is also an important molecule for storage and transportation of energy in the cell. The growth of microorganisms in aquatic system is often limited by some element and it is usually either phosphate and/or nitrogen. The release of large quantities of phosphate could lead to eutrophication of these waters. Most of the world's production of phosphate is used as fertilizer in the agriculture. Another large field of application for polyphosphates is as a water softener in household's detergents and industrial boiler water. The polyphosphate then forms a complex with cations such as calcium and magnesium, which otherwise would interact with the detergent and increased the consumption of the detergent. It also forms a complex with the same cations in the water boiler in order to prevent them from producing scaling with carbonates. Phosphate is also used as feed phosphates and is added as phosphoric acid to soft drinks.

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I.2.5. ACIDITY, ALKALINITY AND SALINITY

José MARTINEZ CALATAYUD

I.2.5.1. Acidity

The acidity of a water sample is by definition, its capacity to react with a strong base until a certain value of pH. The acidity is expressed as the concentration in "milli-equivalent by gram" of hydrogen ions or like the equivalent amount of calcium carbonate that is required to neutralize the acidity.

The determination of the acidity intends "to quantify the acid concentration in a water sample or in a liquid residue". This data is important because the acid substances present in the water are responsible for the corrosivity increase and they interfere with the reaction capacity of many substances by interfering some chemical processes to the interior of the water systems.

Thus, the quantification of acid substances is useful and necessary, as much as it allows its later neutralization and in general, the adjustment of the water for a certain aim or application.

The acidity in the water can be associate to the weak acid presence such as carbon dioxide, to the strong acid presence like the sulfuric, hydrochloric and nitric acids and to the presence of strong salts from weak bases, such as those of ammonium, Fe3+, Al3+, etc. Although the acidity from CO2 has little importance from the point of view of the drinking degree, from the industrial point of view it is very important due to the corrosive power of present acid substances in the water.

The most frequent form to measure the acidity, it is by titration with a strong base, 0.020 mol L-1 Na(OH), generally using as indicator the methyl orange, (turn between 3.1 and 4.4) or the bromocresol green, (color change between 3.0 and 4.6), for the first point and the phenolphthalein, (change over 8.0 - 10.0 for the second point).

Because the pH of the water saturated with CO2 and one atmosphere of pressure is of the order of 4.5, any water sample whose pH is lower than 4, contains some additional acid substances different from carbon dioxide. The concentration of that additional acid substance is known and measured like “mineral acidity”, by titration with sodium hydroxide from the original value of pH to pH 4.5.

Nevertheless, in a natural water system whose pH is over the range 4 - 6, it can be assumed that the acidity must be almost exclusively due to the concentration of CO2. This acidity, known as “carbonic acidity”, is titrated up to pH 8.2 with NaOH by means phenolphthalein.

The addition of these two measurements, expressed in terms of milligrams of calcium carbonate L-1 of solution, is known as “total acidity”. In general, it is not usual

39

for natural water to present mineral and carbonic acidity simultaneously; however, it is frequent in industrial residual waters. The carbonic acidity is by far, the most frequent form of acidity in water.

I.2.5.2. Alkalinity

The alkalinity of a water sample is the capacity to react or to neutralize hydrogen ions, (H+), up to a pH value of 4.5. The alkalinity is caused mainly by bicarbonates, carbonates and hydroxides in solution and in smaller degree by borates, phosphates and silicates. In a strict sense the main species causing alkalinity and their association with the source, are the following:

Hydroxides, natural, residual and industrial waters Bicarbonates and carbonates, natural and residual CO2, underground (deep) and residual

waterSilicates, SiO3

2- and HSiO3─, underground waters

Borates, BO33-, HBO3

2-, H2BO3─ underground and agricultural residual

waters Phosphates, PO4

3-, HPO42-, H2PO4

─ agricultural and industrial waters

In spite of the reported in most of natural water systems, alkalinity is associated to the carbonate system, which means the sum of carbonates and bicarbonates. Due to that, the alkalinity usually is taken as an indicative of the concentration of these substances, (Figure I.2.3.), however this does not mean for all the cases, that the alkalinity is exclusively only due to bicarbonates and carbonates.

The relatively old underground waters running through sandy layers, constitutes a good exception, where the alkalinity is also related to dissolved silicates. The alkalinity in most of the natural water systems has its origin in the system carbonate, because carbon dioxide and the bicarbonates come from the metabolism of the live organisms, aerobic or anaerobic, which can survive in any water, with organic matter and minimum conditions of survival. Since this possibility is frequent in most of the water that surround us, the "system carbonate" is present in all of them:

M. O. + O2 / Fe3+, NO3─, etc. CO2 + H2O

CO2 + H2O H2CO3 ≈ 100 mg of CO2 / liters of water with CN-

H2CO3 H+ + HCO3─

HCO3─ H+ + CO3

-2

One of the main consequences from the acid-basic characteristics of carbonate system is the slight "buffering capacity" of the waters. Thus, the concentration of the

40

system carbonate in the water determines its buffering capacity, and the proportion of these ions CO2, HCO3

- and CO3 2- determines the pH.

00,10,20,30,40,50,60,70,80,9

1

0 2 4 6 8 10 12 14

pHX(FR

AC

CIO

N M

OLA

R)

H2CO3

HCO3─

CO3=

Figure I.2.3. System Carbonate in waters

The alkalinity in the water expresses the equivalent hydroxyl ion concentration, in mg L-1 or the equivalent amount of CaCO3, in mg L-1. The alkalinity, understood as the alkaline-earth metal concentration, it important in the determination of the quality of the water for irrigation and is in addition, an important factor in the interpretation and the control of the processes of residual water purification.

The alkalinity is titrated with 0.02 N HCl by using indicator phenolphthalein, when the original pH of the sample is over 8.3, or methyl orange in the opposite case. The former case is called P Alkalinity, (to phenolphthalein) and in the second of M Alkalinity (to methyl orange). Figure I.2.4 facilitates the selection of an indicator for the measurements of alkalinity or acidity.

Since the alkalinity is a direct function "of the system carbonate" in the sample, the alkalinity values obtained "in situ" usually differ from the ones obtained in the laboratory on transported samples, because these can absorb or release CO 2 before measurements in the laboratory.

These differences are relevant especially in underground water samples because the prevailing pressures to these depths determine the balances of dissolution of gases.

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α

To obtain a more exact value of the alkalinity, it is important to measure the alkalinity "in situ" or in the mouth of the well for deep waters. To obtain a better ionic balance in the joint analytical results of these samples, it could be preferable to let the sample balance to the atmospheric pressure before measurements.

Figure I.2.4. Common indicators and change intervals

I.2.5.3. Salinity

It is the concentration of the soluble mineral salts in the water, mainly of metals like sodium, magnesium and calcium. The mineral salts are good conductors; organic and colloidal matters present low conductivity. Consequently, in the case of residual waters, this measurement does not give an immediate idea of the total contents in the water sample.

The concentration is usually expressed in parts by million (ppm) and according to the present salt concentration there are different water types: Fresh water, less than 1 000 ppm; Slightly salty water, from 1 000 ppm to 3 000 ppm; Moderately salty water, from 3 000 ppm to 10 000 ppm; Highly salty water, from 10 000 ppm to 35 000 ppm (ocean waters are about 35 000 ppm, 3.5%).

Other usual way is to be expressed as psu (practical salinity units); the ocean waters are about 35 psu. The relative amounts of solved salts in sea water have

42

pH

approximately the following figures (in %): 55.3 Cl (I); 30.8 Na (I); 3.7 Mg (II); 2.6 SO4

2-; 1.2 Ca (II) and 1.1 K (I).For seawater, the salinity is defined conventionally as the weight in grams of

dried solid compounds until constant weight to 480º C, obtained from 1 kg of water of sea. It is assumed that the organic matter has oxidized, the bromine and the iodine have been replaced by their equivalent in chlorine and carbonates turned oxides.

In fresh waters the most abundant mineral salts are the carbonates, the sulfates and the chlorides. Cations of greater importance are: Ca2+, 64%; Mg2+, 17%, Na+, 16%; and K+, 3%. The calcium plays a fundamental role in fresh waters since it determines two different water types: a) hard waters, and b) soft waters, the last type is when the concentration is inferior to 9 mg by litter. Many mollusks, crustaceans and other invertebrates, have calcium necessity to form their shells and therefore can be a lim.

The salinity measurement is very important in irrigation waters. Generally, the content of salts is reduced and does not interfere in the good development of the plants, but, in certain places and circumstances, water can contain high concentrations of salts. For this reason, it is highly recommendable to make periodic water analysis in irrigated land operations especially if settled irrigations by dripping are present, where the possibilities of an accumulation of salts in the ground are greater.

The progressive increase of the concentration of soluble salts, due to the continued irrigation, brings an increase of the osmotic pressure of the dissolution in the ground. The greater the concentration of salts is, the greater the osmotic pressure that the roots of the plants will have to surpass before being able to absorb water.

When saline waters are used for irrigation some recommendations are required. The saline water preferably will be used in light and permeable grounds and for tolerant cultures to salinity. And, it is necessary to facilitate the removing of excess of salts by means of a suitable system of drainage. Frequent rain over permeable grounds, makes unnecessary the above-mentioned recommendations, since the rain would wash the grounds. The phreatic level is deep enough to avoid problems by excess of salinity from ground water. The irrigation by aspersion is not recommendable for waters with the conductivity greater than 2 mmhos/cm, since these can damage the installation and produce burns in the leaves of the plants.

I.2.6. ORGANIC POLLUTANTSTomas ALEXANDERSSON

Chemical compounds are regarded as inorganic or organic. This division comes from the ideas that there were differences between compounds originating from living plants and animals and those from non-living sources. The organic compounds contain carbon combined with other elements e.g. oxygen, hydrogen and nitrogen.

43

There is also a difference between synthetic and natural organic compounds. Natural compounds are of course those that can be found in the environment and are produced by bacteria, animals and plants. Synthetic compounds are made by humans. It could be a natural compound, which is produced in large scale or it could also mean a new compound that did not exist previously. There is a very large number of different organic compounds and around 100 000 are in commercial use. Each year a couple of thousand new substances are added to the list.

When a chemical is used it will sooner or later be released into the environment. In order to forecast its effect, it is important to have some knowledge about its characteristics. The impact it could have is a combination of its toxicity, biodegradability and potential for bioaccumulation. The worst scenario would be the release of a persistent (non-biodegradable) chemical, which is also toxic and accumulates in animals and plants.

It is an impossible task to describe every single organic compound. Instead, the most important, from an environmental perspective, groups of organic pollutants will be dealt in this chapter.

I.2.6.1. Sewage

Most of the modern human activities generate waste associated to a water phase. In the manufacturing of products there are usually also some unwanted by-products formed, which must be eliminated. In the factory, these are separated from the product and discharged as a wastewater. Also in households, a lot of sewage is formed due to daily activities. Normally these wastes are collected and treated in some way but not all substances are reduced during this procedure. In the end the treated water is released to some sort of recipient and the remaining compounds can then cause damage to the environment. The disposal of solid waste, both by households and industries will eventually also lead to some generation of sewage. This is due to the atmospheric precipitation that is transported through the landfill and leach out different compounds. The effect these different types of sewage will have on the environment and treatment processes is in some way depending on where they originate. Some different types of wastewater are presented in the following text together with general characteristics for these water types.

Municipal WastewaterThe major contributors to municipal wastewater are households whereas the

share of industrial water may differ significantly from case to case. Besides wastewater, there could also be a significant amount of groundwater that leach into the sewage system and dilutes the water. Municipal wastewater is in general regarded as easily degradable but this could be changed if the share of industrial load is increased. If the water is let out to a recipient without treatment it would lead to eutrophication and lack of oxygen in the receiving waters. To avoid this municipal wastewater is

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treated in treatment plants. To achieve a far-reaching treatment the plant should consist of three different steps. First particular matter is removed with a screen and sedimentation. Remaining particles and dissolved compounds are reduced in a biological step, which usually is some kind of activated sludge process. The activated sludge is a suspension of microorganisms that nourish on the components in the water while they are reproducing. The suspension is settled in a subsequent step and the water is led to the final stage, chemical treatment. When the microorganisms are growing in the biological step they also require nutrients that also are present in the wastewater. However, the amount of the major nutrients nitrogen and phosphorous are usually larger than what is required. In the chemical step the surplus of phosphorous can be removed by precipitation with metallic salts. A final clarifier removes the particles created in the chemical step and the cleaned water is discharged to the recipient.

Industrial WastewaterThe wastewater from the industry is much more diverse compared to the

wastewater from households, which have a uniform composition despite origin. However, a classification of industrial wastewater can be done based on the type of industry. The following reasoning is of a more general nature and there exists situations where the conditions are somewhat different.

In the pharmaceutical industry the products are usually produced in batches during different campaigns. In addition to this, there are also always some new products included in the production plan or other products are either removed or produced by a changed process. These continuous changes will be reflected in the wastewater composition. So, the water from a pharmaceutical industry would normally vary a lot, perhaps not on a day-to-day basis but on a week-to-week basis. Although the purpose is to produce the product for sale, small residuals quantities may enter the wastewater due to the cleaning of process equipment. Besides products, the byproducts formed during the production process and impurities retrieved during processing may end up in the sewage. These waters could also contain toxicity since the products are designed to be biochemically active.

In the metallurgic industry several operations such as pressing, drilling and rolling are used during the conversion of metal to the final product. Before the product reaches the final market its surface is also painted, passivated or treated in some other way. In some process steps the object is contaminated with grease or cutting fluid, which has to be removed before any further processing can be done. Normally this is done in some degreasing step using alkaline, acid or neutral cleaning solution, which is followed by several rinsing steps. The cleaning solution, rinsing water and other types of surface conditioning baths have to be renewed with regular intervals and some of it is then purged as a wastewater. This sewage may contain metals, tensides, grease and complexing agents and may either have a low or high pH. Some process

45

streams may also contain cyanide and chromium, which require special treatment before they can be discharged.

Foodstuff is produced both in batch and continuous processes and wastewater is generated above all during washing and rinsing of process equipment. Depending on the actual production type there may be large or small variations in the wastewater concentration. However, the components in the wastewater are usually harmless and easily degradable.

The pulp and paper industry produces a broad range of paper products as e.g. newspapers, journal papers, containerboard and different special paper such as filters and thermo paper. All these products are formed from cellulose fibers, which originate either from virgin fibers or from recycled fibers. The production of paper can be regarded as a two-step process. In the first step fibers are detached from the wood either mechanically or chemically. Depending on what type of product will be made from the free fibers, which are referred to as pulp, they are bleached in order to increase the pulp's whiteness. The pulp is then used in the second step when the paper product is formed. The pulp is mixed with water and several additives to a furnish, which in the paper machine is converted to paper. A lot of water is used both in the production of the pulp and the final paper product. The water consumption is usually higher for special paper and fine printing paper than for board made from recycled fibers. When this water is too contaminated and can not be used any more it is discharged. The composition of the wastewater depends on the production process and what type of raw material that is used. Process streams from debarking and bleaching can be harder to degrade and may also be colored. Other streams are usually more degradable and not so colored.

I.2.6.2. Surfactants

Surfactants (surface active agents) are molecules that are acting at the surface between polar and non-polar phases. One part of the molecule is hydrophobic and the other is hydrophilic. The hydrophobic part is made up of a long hydrocarbon chain, which prefers to be dissolved in a non-polar medium. A polar group or a group that can establish hydrogen bonding is situated at hydrophilic end of the molecule. This part prefers to be immersed in the water phase. A schematic view of a surfactant can be seen in Figure I.2.5.

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CH2CH2 CH2 CH2CH2 CH2

CH2CH2 CH2 CH2CH2 CH2CH3

COO-Na+

Hydrophobic part Hydrophilic part

Figure I.2.5. Structure of the surfactant, sodium myristate, with the hydrophobic and hydrophilic parts denoted.

When enough surfactants are added to water they interact with each other under the formation of small micelles consisting of 50 to 100 individual molecules. The micelles look like a sphere with the hydrophobic end towards the centre and the hydrophilic parts on the outside towards the water. Treating a dirty surface with this water solution causes the hydrophobic substances as grease and fat to dissolve into the centre of the micelles. The hydrophobic substances are thus removed from the surface and kept in the water phase as a stable emulsion. This effect could be used for cleaning, creation of emulsion and foams. Surfactants are used in many different products such as soaps, detergents, shampoo and hair conditioners.

Surfactants can be divided into different categories depending on the electrical charge at the hydrophilic end of the molecule:

anionic, which have a negative charge, cationic, which have a positive charge, nonionic, which are neutral, amphoteric, which have both a positive and negative charge.

The first forms of surfactants were not so degradable, which led to the formation of stable foams in wastewater treatment plants and recipients. This started a debate about their negative impact on the environment and a development towards better products. The first surfactant was made up of highly branched alkyl sulfonate, which was persistent towards biological degradation. These were then replaced by linear alkyl sulfonate, which is easier to degrade. Today's surfactants are usually highly biodegradable since they often are composed of functional groups that exist in natural materials. Surfactants are regarded as harmless towards mammals whereas aquatic organisms are usually affected with a LD50 in the mg/L range. It is particular cationic surfactants that are toxic and they are also used as germicides and disinfectants. However, other types of surfactants exist, such as alkylphenol ethoxylates and are toxic. One example of a surfactant belonging to this group is nonylphenol ethoxylate, which is biodegradable but not completely degradable. It is converted to nonylphenol, which is persistent, bio-accumulative and is toxic towards

47

aquatic organisms. However, most surfactants are not accumulating in organisms, probably due to the high degradability, but cationic surfactants may bind to organic material and sediment by sorption.

The impact of surfactants in seawaters can be seen also in the coastal vegetation. Decline of coastal vegetation has been reported in several countries, affecting a variety of species and countries (Badot and Badot, 1995; Bussotti et al. 1995; Garrec and El Ayeb 2001), and can be attributed to the presence of surfactants transported by winds and deposited on the leaves. In this case, surfactants are absorbed via cuticles and stomata, causing direct damage to cell membranes, destroy chloroplasts and other cellular organelles (Bussotti et al. 1997). Indirect action can be observed, the saline components absorption is enhanced by the reduction of the water surface tension. Damage caused by sea spray carrying surfactants is usually observed within 100 meters from the seashore, near the mouth of rivers or harbors. Symptoms consist in leave discoloration and necrosis beginning form the apex of the leaf.

I.2.6.3. Halogenated Carbons

Halogenated carbons are a group of chemicals with one or two carbon where some or all of the hydrogen has been substituted by a halogen. The group of chemicals where either chlorine or fluorine atoms has replaced all hydrogen is referred to as chlorofluorocarbon (CFC). In hydrochlorofluorocarbon (HCFC) and hydrofluorocarbon (HCF) there are some hydrogen atoms left. The substitution of hydrogen with a halogen gave the molecule characteristics making the chemicals suitable for use as refrigerants, in making plastic foam and as cleaning agent of electrical units. Although the chemical during its use as e.g. refrigerant is in a closed container large amounts have been released into the atmosphere. It has been estimated that 90% of what have been produced as dichlorodifluoromethane have been released to the air and the cumulative production of this chemical up to 1990 was approximately 107 ton. The problem with the released chlorofluorocarbons is that they are inert and they diffuse to the upper atmosphere. There they start to deplete the ozone layer by a number of reactions with the result that ozone is converted to oxygen. The ozone layer functions as a protective fence against ultraviolet radiation and when it is damaged this radiation reaches the earth's surface causing damage such as skin cancer.

I.2.6.4. Polycyclic Aromatic Hydrocarbons

Polycyclic aromatic hydrocarbons (PAH) are a large group of chemicals made up of only carbon and hydrogen. They differ in size but have at least two condensed aromatic rings in one plane. The smallest PAH is naphthalene, which structure can be seen in Figure I.2.6.

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Figure I.2.6. Chemical structure for naphthalene.

The number of aromatic rings, in the most environmental important compounds, range from two to seven. Different alkyl groups can be attached to these aromatic rings and thereby increasing the number of possible combinations.

PAHs are formed in imperfect combustion processes when oil, coal, petroleum products or organic matter is incinerated. Examples of such human activities are coal–fired electricity power plants and internal combustion engine in different vehicles. Smoking tobacco is also an activity, which produces PAH. It is not a large contributor on the whole but it is important since it exposes the smoker and the immediate surroundings to large amounts of PAHs. These compounds are also generated naturally during forest fires and volcanic eruptions.

It is found that PAHs are causing cancer and one of the most dangerous compounds is benzo(a)pyrene (Figure I.2.7.). Most PAH are also considered to be persistent, toxic and accumulates in organisms.

Figure I.2.7. Chemical structure of benzo(a)pyrene.

I.2.6.5. Dioxins

Polychlorinated derivatives of dibenzo(1,4)dioxin are referred to as dioxins and the chemical structure for the most toxic one, 2,3,7,8 tetrachlorodibenzo(1,4)dioxin (TCDD), can be found in Figure I.2.8.

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Cl O

OCl

Cl

Cl

Figure I.2.8. Chemical structure for 2,3,7,8 tetrachlorodibenzo(1,4)dioxin (TCDD).

TCDD is actually among the most toxic compounds that the humans have made. Dioxins do not have any commercial use but are formed as by-products in mainly two different processes:

Chemical processes where chlorine is used. Different combustion processes.

Examples of chemical processes where chlorine is used are manufacturing of chlorinated organic compounds and bleaching of pulp with chlorine. Many mills have replaced chlorine with other bleaching agents such as hydrogen peroxide or ozone and could thereby avoid the formation of dioxin. Combustion of organic matter at high temperature and with presence or chloride ions will also lead to the production of different dioxins. This happens in e.g. solid waste incinerators and coal-burning power plants.

The characteristics, such as toxicity and persistency, for the different forms of dioxins are of course varying but they are usually regarded as toxic and persistent. They are widespread in the environment and have been found in sediments, fish, mammals and human breast milk.

I.2.6.6. Polychlorinated Biphenyls

Polychlorinated biphenyls (PCBs) are a group of important environmental pollutants, which resemble dioxins in many ways. They consist of a biphenyl with one or more chlorine atoms attached to the aromatic rings. One example of a PCB is 2, 2', 3, 4, 5'-pentachlorobiphenyl, which structure can be seen in Figure I.2.9.

Cl Cl

Cl

Cl

ClFigure I.2.9. Chemical structure of 2, 2', 3, 4, 5'-pentachlorobiphenyl.

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PCBs are thermal stable and since they are also non-inflammable and have suitable electrical characteristics they were used as heat transfer fluid in electrical capacitors and transformers. They have also been used as hydraulic fluid and lubricant. Through its normal use and deposition of components containing PCB it has spread into the environment and may even be found in the polar regions.

There is a general conception that PCBs show a low acute toxicity towards humans but the chronic toxic effect are, however, more alarming. PCB are known to cause damage to the liver and can also affect the skin, a condition known as chloracne, which also other chlorinated aromatic compounds can cause. It is very toxic towards aquatic organisms and accumulates in the environment. It also disrupts the reproductive ability of mammals and fish.

I.2.6.7. Brominated Flame Retardants

Flam retardants are used for obstructing the start of a fire and to damp down a started fire. They are very effective and only small amounts are needed to achieve the desired function but they do not make the treated material non-flammable. The five most used retardants belong to three different chemical groups:

1. Diphenyl ethers (Figure I.2.10.) (pentabromodiphenyl ether, octabromodiphenyl ether and decabromodiphenyl ether),

2. Bisphenols (Figure I.2.10.) (tetrabromobisphenol A),3. Cyclododecanes (hexabromocyclododecane)

O OHHO C

CH3

CH3

Figure I.2.10. Chemical structures for to the left Diphenyl ether and to the right Bisphenol A. The specific retardants belonging to group 1 and 2 are derivatives of these basic structures.

Like all other chemicals the environmental effect from each substance varies from compound to compound and especially in this case as they belong to three different groups. Although they belong to different groups the five most used

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retardants are all regarded as persistent. Most of them are also very toxic towards aquatic organisms and bio-accumulative.

I.2.6.8. Phthalates

The schematic structure for phthalates can be found in Figure I.2.11 and it shows that phthalates are diesters of phthalic acid and alcohols.

The alcohol can either be aliphatic or aromatic and by having different alcohols the resulting chemical will acquire slightly different qualities. In general phthalates are used as a plasticizer in plastics and rubber.

C R

O

O

C R

O

OFigure I.2.11. Schematic chemical structure of phthalates.

The physical and chemical properties of the phthalates have made them suitable as plasticizers in polymers such as plastic and rubber. Phthalates can be found in various products such as flooring products, wallpapers and cables. Some phthalates are also used as binders in coloring and adhesive substances. Since they are just added to the product and not chemically bonded to it the product will slowly release phthalates. Therefore, phthalates can be found almost everywhere in the environment.

The three in use dominating phthalates are di(2-etylhexyl)phthalate (DEHP), diisononylphthtalate (DINP ) and diisodecylphthalate (DIDP). The information about DEHP reveals that it is toxic and may affect the reproductive capacity and cause fetal damage. The environmental effect from the other two phthalates is still not explored.

I.2.7. PESTICIDES

Jenny EMNEUS

Pesticides are compounds that are used in order to eliminate pests of different kinds such as insects, weeds and fungi. The different agents are then referred to as insecticides, herbicides and fungicides. There is a large group of chemicals used as

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pesticides and they can be divided into several classes. Each class is more or less efficient towards the different pests.

I.2.7.1. Chlorinated Pesticides

The development of chlorinated pesticides started when it was discovered that DDT (Figure I.2.12.) could be used as an efficient insecticide.

The use of DDT escalated during the Second World War when there was a big demand of insecticides for preventing food spoilage and diseases from spreading. There were several benefits with DDT: It was relatively cheap and easy to produce, it was persistent, which prolonged the effect after treatment and had low toxicity towards mammals. However, concern against the product started to develop during the 60s when it was discovered that it caused reproduction damage for birds of prey. It disrupted the enzyme system responsible for the egg production, which resulted in eggs with very thin shell. The number of surviving off springs decreased as the eggs broke before they were ready for hatching.

ClCl CH

CCl3

Figure I.2.12. Chemical structure for dichlorodiphenyl trichloroethane, more known as DDT.

I.2.7.2. Organo-phosphoric Pesticides

Organo-phosphoric pesticides originate from the military gases that were developed during the Second World War. They are not considered bio-accumulative since they are hydrolyzed when they come in contact with water. The toxic effect comes from interference with the transmission of nerve impulses and they affect all organisms from mammals to insects.

I.2.7.3. Carbamate Pesticides

Carbamate pesticides are very similar to the organophosphoric pesticides regarding use and characteristics. They are often used when organophosphates are inadequate but are at the same time more expensive. Another difference is that carbamates do not have the long-term effect as organophosphates presents.

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I.2.7.4. Pyrethrins and Pyrethroids

The Chrysanthemum plant contains the natural insecticide pyrethrum, which belongs to the group pyrethrins. These compounds act as neurotoxins and affect the ion balance. Mammals are generally not affected since they are able to rapidly degrade the pyrethrins and the compounds toxicity towards mammals is also low.

Synthetic compounds that mimic the molecular geometry of pyrethrins have been developed and they are named pyrethroids. These compounds are also effective as insecticides and their stability towards moisture and light have been improved compared to the natural pyrethrins. However, some of these pyrethroids have an increased toxicity towards mammals and are in general highly toxic towards fish.

I.2.7.5. Phenoxyacetic Acid Herbicides

Phenoxyacetic acids are a group of herbicides, which are also known as hormone weeds. They were, as many other pesticides, developed during the Second World War and the development was based on the structure of the natural hormone auxin. These herbicides show low toxicity towards aquatic organisms and also a low persistence. The problem with these compounds is that during the production some very toxic dioxins are also produced. These contaminate the product and are the reason why this type of herbicide is banned in many countries.

I.2.8. RADIONUCLIDES

Diana Cristina ANDREI

Among the 2300 nuclides that have been identified, most of them are radioactive. However, in their daily life, people are likely to encounter only few radionuclides. Among those, there are the radionuclides corresponding to the natural radiation (cosmic radiation, primordial radioactive elements in the earth’s crust and their radioactive decay products, etc.) as well as the radionuclides routinely used for medical, military and commercial purposes.

Example: Decay of uranium - 238 and thorium - 232 conduct to the existence of trace elements in rocks and soils. Table I.2.2 presents a list of few radionuclides of interest and their type of emitting radiation.

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Table I.2.2. Radionuclides and their characteristics

Name Atomic Number

Radiation TypeAlpha Beta Gamma

Americium-241 95 Cesium-137 55 Cobalt-60 27 Iodine-129 &-131 53 Plutonium 94 Radium 88 Radon 86 Strontium-90 38 Technetium-99 43 Tritium* 1 Thorium 90 Uranium 92 *tritium is a specific isotope, H-3.

Usually, alpha emitters occur naturally, but several can come from man-made sources. They may be found in ground water and surface water. Beta and gamma emitters are mainly man-made and are frequently associated with nuclear power plants, facilities that use radioactive material for research, manufacturing, etc.

The three exposure pathways of humans to this radiation are inhalation, ingestion and direct (external) exposure. Living tissues in the human body can be damaged by ionizing radiation (from radionuclides). If at first, this was learned through observation, today the statement is a well-known fact. Moreover, it is difficult to set a “safe” level of exposure above background; any exposure carries some risk and that risk increases as the exposure increases.

Several types of cancer may occur with death as result of extremely high dose of radiation. Thus radon can cause lung cancer, with affecting water drinking and leading to stomach cancer. High exposure of radium-226 and radium-228 has been known to cause bone, stomach, lung or other forms of cancer. Uranium may have a role in the development of bone cancer and is toxic to kidneys too.

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I.3. SONIC AND ELECTROMAGNETIC POLLUTION

Diana Cristina ANDREI

I.3.1. THE SOUND

I.3.1.1. Introduction

We live in a world of sounds, undoubtedly essential in terms of communication and/or transfer of knowledge. Nature furnishes us with an abundant variety of sound sources, but it’s the man-made ones that often raise problems for the environmental health and will be discussed here. Besides the sources of sonic energy, the existence of sound implies one or more media through which this energy is transmitted. Thus, the sound may be defined as “a form of radiation which involves pressure waves in matter”.

The pressure fluctuations (as seen in Figure I.3.1.) are of a vibrational nature, causing the neighboring air pressure to change with no apparent movement of air taking place. These pressure variations create in humans the aural sensation called commonly “the sound”.

Figure I.3.1. Representation of sound

Short History of AcousticsThe word “acoustics” is derived from the Greek word meaning hearing.

Although interest in acoustics was shown through music and architecture as early as ca. 4000 b.c. by ancient Egyptians, Hindus, Chinese and Japanese and later by renowned antique Greek figures such as Phytagoras, Aristotle, or the amphyteatre architect Marcus Vitruvius Pollio, it was not until the seventeenth century that the nature of sound was critically examined with carefully planned experiments. Thus, in 1636, a Franciscan friar named Marin Mersenne (who is often called today “the father of acoustics”) performed the first experiments which aimed at the determination of the speed of sound in air. These measurements were repeated in different circumstances during the next three centuries with greater refinements about the World War I due to the usage of microphones. Nevertheless, the experiments regarding the velocity of sound in solids and liquids were not performed until early in the nineteenth century. In 1808, J. B. Biot, a French physicist measured the speed of sound in iron, while

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Daniel Calladon, a Swiss physicist determined its speed in water. The temperature dependence of the velocity of sound was established during one of the Arctic expeditions.

Although the science of acoustics was continuously developed over the centuries, the system that has changed our civilization forever was telephony, the principle that allowed human speech to be transmitted at great distances. It was in the summer of 1874 that Graham Bell, a professor of vocal physiology at Boston University conceived the first speaking phone. Today, only in Bucharest, the number of fixed telephones raises to 1 797 556, with a number of 3 457 000 in the whole Romania for Mobile phones sold only by Connex.

Another revolutionary discovery which enveloped the world with speech and music was radio broadcasting. The young Italian physicist Guglielmo Marconi put together in 1896 a number of electronic devices and demonstrated his system to the Italian Navy in the Mediterranean. After this event, the development of broadcasting was so rapid that in 1927, the Federal Radio Commission of the United States was granted legal authority to control wavelengths and regulate power. In 1939 the TV invention followed, and today the broadcasting all over the world is stronger than ever.

Whatever the period of history, men seem to have an insatiable desire for change that music can easily offer even in a constant environment. Talking about acoustics invariably relates to talking about music, therefore a summary of its history may be required here.

The development of music is divided by historians into three different periods:(1) homophobic or unison music (up to the eleventh century);(2) polyphonic music with several parts, but without any independent musical

significance of the several voices (up to the seventeenth century);(3) modern polyphonic music in which many melodic lines were superposed.Modern music has benefited greatly from Thomas Edison’s two inventions,

the phonograph (1877) and the motion picture machine (1891). Also, in 1889, the first magnetic recorder was invented by Valdemar Poulsen in Denmark.

New sounds of music in the twentieth century were only made possible by the developments of electrical engineering and have continued to grow in size and diversity.

Frequency (f)This is the number of vibrations or pressure fluctuations that a sound source

undergoes per second. The sound emitted from the source will propagate with the same frequency. The unit is the Hertz (Hz).

Example: 440 cycles/sec = 440 Hz for a violin string.

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Wavelength ()This is the distance traveled by the sound during the period of one complete

vibration (see Figure I.3.1). The unit is the meter (m).

Velocity of Sound (c)The frequency and wavelength of a sound wave are related by the simple

formula:

c = f (1)

Equation (1) shows that the velocity of sound (c) in a given medium is a constant. It is sufficiently accurate for the purpose of building acoustics to consider this value equal to 330 m/s. However, sound propagates in different media at different speeds with small temperature dependence that is the principle responsible for the bending of the sound in the atmosphere.

Examples: the velocity of sound in brick is equal to 3650 m/s or in a steel bar, 5060 m/s; the velocity of sound in water is at 20ºC, 1482 m/s.

Propagation of Sound WavesSound is thus a longitudinal wave, i.e. the vibrations are in the direction of

motion (see Figure I.3.1.). As a wave, sound shows all wave properties: absorption, reflection, diffraction and interference. However, as a longitudinal wave, sound cannot be polarized.

Pressure (p), Intensity (I); Sound Pressure Level, Sound Intensity LevelThe magnitudes of sound pressure affecting a healthy human ear vary from

2x10-5Pa at the threshold, up to 200 Pa in the region of instantaneous damage. In comparison with the normal atmospheric pressure of 10-5 Pa, these magnitudes have a wide range, therefore, for the mathematical usage, a logarithmic scale proved accurate describing also the actual non-linear ear response to pressure variations (Weber-Fechner law).

Sound intensity (I) is proportional to the pressure (p) as in the formula below:

I p2 (2)

The unit is the W/m2.

The two important parameters associated with sound are the sound pressure level and the intensity level. They are defined by the following:

(1) Sound pressure level = 20 log10(p/p0) (3)

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where p0 is the pressure at the average threshold of hearing at 1000 Hz frequency (e.g. 2x10-5 Pa) and p is the applied sound pressure,

(2) Sound intensity level = 10 log10(I/Io) (4)where I0 is the minimum threshold intensity (e.g. 10-12W/m2) and I is the applied sound intensity.

Sound intensity is a more complex measure for sound as the rate at which acoustic energy passes through the unit area perpendicular to the direction of propagation of the wave. Both types of level are expressed in decibels (dB) and have, according to definitions (3) and (4), the same value in the particular case of a plane wave. However, the sound intensity level is a directed quantity giving information also on the direction of the sound flow. Table I.3.1 shows the characteristics of few representative sounds.

Table I.3.1. Representative sound levels

Sound Intensity (W/m2) Intensity level (dB)Threshold of hearing 10-12 0

Rustling leaves 10-11 10Whispering 10-10 20

Normal conversation 10-6 60Busy street 10-5 70

Pneumatic drill 10-3 90Jet overhead 10-2 100

Threshold of feeling 100 = 1 120Threshold of pain 102 =100 140

PowerIt is convenient to express the total sound output from a source as power. This

is equal to the intensity multiplied by area. The unit is the Watt (W).Examples: A loud voice reaches about 1 mW, a large orchestra 10 W, whereas

a jet plane may generate values of up to 100 kW.

I.3.1.2. Aural Environment

The EarThe auditory apparatus of man with the ear as its vital component is

exceedingly complex. Its permanent function is that of converting the sound pressure waves of the surroundings into signals that are sent to the brain; the ears are never

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closed. Figure I.3.2 presents the main components of the ear, showing the outer, middle and inner anatomical parts.

Figure I. 3.2. Sketch of the anatomical parts of the ear

The sound reaches first the outer (visible part) of the ear, the pinna. Designed with a concave shape, the pinna scatters longer wavelengths, while reflecting the shorter ones into the auditory tube (meatus). The meatus ends into the tympanic membrane, which, due to its size (2.5 cm in length and 5-7 mm in diameter), resonates to a frequency of about 3 kHz.

The middle ear is an air-filled cavity that picks up, amplifies (20 times) and transmits the vibration motion of the eardrum to the inner ear. A chain of tiny bones (hammer, anvil and stirrup) suspended and constrained by ligaments and small muscles in here has the role of a shock absorber for the excessive overpressures associated with certain sounds (e. g. levels above 90 dB for more than 10 ms). The air in this enclosure is maintained at atmospheric pressure through the Eustachian tube that connects the ear to the mouth.

The inner ear is a system of fluid-filled canals protected acoustically inside the temporal bone of the skull. Under the influence of sound, the stirrup strikes a small opening covered by a membrane at the beginning of the inner ear causing its vibration and transmitting this way the pressure to the fluid within. Three semicircular canals are disposed as one for each dimension of space furnishing us with the sense of equilibrium. However, the most important part of the inner ear is the cochlea, which contains the final receptor for the hearing. Long of about 40 mm, cochlea supports as a

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result of fluid movements the bending of the little hair cells (Corti organ) within. Thus, nerve impulses (2400 endings) are initiated and transferred via the auditory nerve to the temporal lobe of the brain giving us the sense of “sound”.

Audible RangeThis extends in frequency for humans between 20 Hz and 20 kHz and depends

upon the age and physical condition of the individual. Frequencies above and below this range are known as ultrasonic and infrasonic, respectively.

Figure I.3.3 shows the average threshold curve for the young adults with normal hearing. It can be seen that the human sensitivity varies considerably over the audible range, especially near the threshold of hearing where variation is of about 70 dB. Maximum sensitivity is reached in the range of 3 kHz as dictated by the anatomy of the outer ear. At this level, the acoustic threshold intensity is of the order of magnitude of 10-12W/m2 and the physical displacement of the eardrum has been found to be as minute as 10-9 cm. Figure I.3.3 shows also that some discomfort is apparent at 120 dB, and sensations of tickle and pain are experienced in the case of every frequency that exceeds 140 dB.

Figure I.3.3. Diagram of the approximate threshold of hearing for young people (age 18-25)

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PitchUnlike frequency, which is an objective measure, pitch is a subjective term

depending mainly on frequency, but also on intensity, the wave form and the duration of the signal. The sensation of pitch is usually alluded to in terms of “high” and “low”. The unit is the mel.

Example: A tone having a frequency of 1000 Hz is arbitrarily defined as having a pitch of 1000 mels. Figure I.3.4 shows the relationship between pitch in mels and frequency.

Figure I.3.4. Relationship between pitch in mels and frequency

Loudness This is also a subjective effect that is a function of the ear and brain as well as

the intensity and the frequency of the vibration. A sound that is regarded loud to one person may not appear as loud to another whose hearing is poor. Moreover, due to the ear’s variations in sensitivity to different frequencies, two notes that are equal in intensity and different in pitch may not sound equally loud, even to a single observer. The unit is the Figure I.3.5 shows a range of equal-loudness contours for a normal ear.

The curves illustrate the fact that loudness becomes less frequency dependent as the level of loudness increases. Also, at 1000 Hz, loudness and intensity levels are numerically equal.

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Figure I.3.5. Equal loudness contours

NoiseNoise is often referred to as any unwanted sound, the concept varying greatly

for each individual according to his interests, activities or mood. Despite its versatility, the categories of noise generally accepted are:

(1) ambient or background noise;(2) steady-state noise;(3) fluctuating or intermitting noise and(4) impulsive noise.

(1) Ambient noise describes the noise in the environment from both near and far away sources. This does not include strong sounds.

(2) Steady-state noise often refers to sound generated by machinery with levels reasonably constant during the period of measurement.

Examples: Railway noise, industrial noise.(3) In case of fluctuating noise the sound may vary in level but it is “on” (above the

ambient level) for times longer than 200 msec (the integration time of the ear).Examples: Traffic noise, open-air concerts, discotheque noise.

(4) An impulsive noise is the noise of a very short duration for its peak pressure level.

Examples: Dropping of a hard tool on the floor, beeping of a car.

Hearing DefectsHearing defects are the effects of noise on humans that are the easiest to be

clinically evaluated. Diseases such as presbycusis, tinnitus or conductive, nerve or

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cortical deafness are diseases of the ear which may or may not involve the factor noise. However, it is considered that the hearing ability is a function of three variables: noise characteristics, exposure time and age.

The intensity level of a sound to cause immediate permanent deafness is that of the order of 150 dB (see Figure I.3.3.). Moreover, the noise-induced hearing loss depends on frequency as shown in Table I.3.2, with narrow band noise being more damaging than broadband noise. The harmful effect to hearing of long duration noise is more difficult to assess and the limits variable. Here we will consider that a safe occupational approach would be an exposure of 5 working hours per day below the levels presented in Table I.3.2. Age alone may cause hearing loss, although other interferences are with certainty present.

Table I.3.2. Maximum levels of noise

Frequency (Hz)

37.5-150

150-300 300-600 600-1200 1200-2400

2400-4800

Value (dB) 100 90 85 85 80 80

Other Effects of NoiseIt is known for several decades now that noise can induce responses in the

human body that are not related to the auditory system. These are both physiological and psychological effects. The intensity level region corresponding to psychological effects begins with 30-60 dB, while that related to the physiological effects is 60-90 dB.

In most instances a physiological change is evident only during or for a short period after the noise manifestation. However, long time exposures may conduct to severe modifications of the physiological equilibrium of the body. Greatly affected are the circulatory, endocrine, digestive and respiratory systems. The most common circulatory effects of noise are the raise in blood pressure, raise or decrease in pulse according to frequency as well as a reduction in peripheral blood flow. Among the endocrine glands, the thyroid has the highest susceptibility to noise. Also, the diminishing of the gastric secretions and of the bowel movements at different levels of exposure are important effects. Changes in the breathing pattern have been noted for intermittent noise with an increase in the quantity of the carbon dioxide eliminated.

Psychological effects of noise are harder to be quantified. However, irritability, annoyance or negative emotions, disorders reflected in lack of attention or vigilance, speech interferences or finally sleep disorders are no less to be considered.

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I.3.2. ELECTROMAGNETIC POLLUTION

I.3.2.1. The Electromagnetic Fields. An Introduction

Electric Current. Magnetic FieldElectric charge in motion is an electric current. A current generates a magnetic

field. The time varying electric field together with its co-dependent magnetic field give rise to electromagnetic (EM) radiation. EM radiation is a transport of energy in the form of an EM wave. This wave may be regarded as an oscillatory wave (Figure I.3.6.) propagated through a volume of space.

Figure I.3.6. Representation of an electromagnetic wave

Frequency (f)This is the number of complete oscillations or cycles of an EM wave detected

by a stationary observer in one second. The unit is the Hertz (Hz).Example: the oscillatory electric charge motion which comes as an alternating

current (a.c.) in all houses with electricity; 60 Hz in North America, 60 Hz elsewhere.

Wavelength ()This is the distance occupied in space by one EM cycle. The unit is the meter

(m).

Velocity of the Electromagnetic Wave (v)The frequency and wavelength of an EM wave are related by the simple

formula:

v = f (1)

Example: the velocity of EM waves in vacuum (air) is equal to 3x108 m/s, the speed of light.

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The Electromagnetic Wave SpectrumEM waves are thus transversal waves, i.e. the vibrations are perpendicular to

the direction of motion. As all waves, EM waves show properties such as absorption, reflection, refraction, diffraction and interference. Moreover, as transversal waves, they also show polarization effects.

The classification of EM waves by their wavelength or frequency is behind the idea of the EM spectrum (Figure I.3.7.). The frequencies corresponding to the energy power supplies (50; 60 Hz) are related to the so-called “extremely low frequency” electric and magnetic fields. As the frequency goes higher, the audio-range is reached, then radio frequencies, television and microwaves. Higher regions define the infrared, visible and ultraviolet light and lastly, the X-rays and gamma rays.

FigureI.3.7. Spectrum of the electromagnetic waves

In 1996 the World Health Organization (WHO) defined the EM fields (EMF) as those with frequencies in the range from 0 to 300 GHz. Generically, this domain is

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divided into the following regions:(1) extremely low frequency (ELF): 0-300 Hz;(2) intermediate frequency (IF): 300 Hz-10 MHz;(3) radiofrequency (RF): 10 MHz-300 GHz.EM energy in the natural fields is almost entirely in the ELF spectrum.

Moreover, there is no significant level of natural energy at radio/microwave frequencies.

Intensity. Flux DensityAn electric field may be described by its magnitude (E), and the electric flux

density (D). The units are (V/m) and (coulomb/m2), respectively. The two quantities are related by the permittivity (), which defines the electrical properties of the medium:

D = E (2)

A magnetic field is described by its magnitude (H), and the magnetic flux density (B). The units are (A/m) or Øersted (Ø) and Tesla (T), respectively. In this case, the two quantities are related by the permeability ()of the medium:

B = H (3)

The permeability of biological materials is taken to be equal to the permeability of free space.

Electromagnetic PowerThis is the rate of EM energy flow. The unit is the Watt (W). Often, the flow

of EM radiation is described energetically in terms of its power density, the power incident upon an area of one square meter. The unit is W/m2.

Example: the EM power density of the Sun upon the Earth equals a value of 1.4 kW/m2; the power density from a typical 800 kW TV broadcast transmitter at a distance of 55 km is equal to 20 mW/m2.

I.3.2.2. Electromagnetic Environment

Electric Field of the EarthThe electric field of the Earth is produced by the local build-up of electric

charges at the surface of the Earth (negative) and in the atmosphere in contact (in excess, positive). The gradient thus formed reaches values of 120-150 V/m with an influence to humans of 200-250 V foot to head. These static electric fields vary greatly in value according to the weather, cosmic phenomena, topography; the gradient is very high when fog and negative during rainy weather.

Healthy people, used to the open-air life easily undertake the Earth electric

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fields changes (e. g. during storms), whereas the cardiac or other sufferers may have strong physiological reactions to these changes.

Magnetic Field of the EarthThe Earth may be compared with a huge magnet whose magnetic field has a

low intensity at its surface of 0.5 Øersted. This field varies slightly in magnitude during the day and also during the month (<1% variation). These fluctuations define the magnetic calm. During solar activity intensifications, magnetic storms occur which may affect labile people (those with circulatory, neural diseases, etc.).

Electromagnetic Man-Made WavesSince the turn of the century, and more precisely, since the 1950-s, the

humanity has surrounded itself with artificial electric and magnetic fields as a result of the increasing use of electricity as an indispensable part of every day life. A short history of EM radiation usage would be very difficult to draw, however there are around 90 years since public radio transmissions began and 60 years since radar was first used. Today, it is believed that our exposure is 200 million times greater than in the beginning of the century.

The Table I.3.3 lists a number of the most important man-made EM waves along with their corresponding frequencies and wavelengths.

Table I.3.3. Characteristics of man-made waves

Application Frequency (Hz) Wavelength (m)Power transmission 50 6000 kmSub-sea communications 75 4000 kmAudio (20 Hz to 20 kHz) 1 kHz 300 kmLong wave radio 100 kHz 3 kmMedium wave radio 1 MHz 300 mFM radio 100 MHz 3 mTerrestrial TV broadcast 600 MHz 500 mmMobile phones 900 MHz 330 mmRadio astronomy 1.42 GHz 214 mmGlobal positioning system 1.5 GHz 200 mmMobile phones 1.8 GHz 165 mmMicrowave ovens 2.45 GHz 122 mmWireless networks radar 5 GHz 60 mmImaging radars 30 GHz 10 mmFiber -optic communications 30 THz 10 mFiber-optic communications 230 THz 1.3 m

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As presented here, artificial EM waves have single, sharp frequencies, unlike natural radiation, where the range is broader. Moreover, some wavelengths of man-made EM waves are similar to those of natural waves (i.e. 214 nm corresponds to both the hydrogen line and radio astronomy emissions; 10 mm corresponds to far infra-red radiation as well as the fiber optic communications).

Electromagnetic Radiation at HomeIn homes located far from power lines, the background EM fields may reach

values of about 0.03 T in case of properly wired buildings, or higher values of 0.2 to 3 T in case of faulty wiring. However, just beneath the lines, the levels of electric fields may be as high as 10 kV/m with a severe decrease in magnitude as the distance increases. Thus, at 50 to 100 m distance, the fields have again background levels. In addition, house walls or just the roofs and trees decrease significantly the electric field levels, even those corresponding to the Earth. When power lines are buried into the ground, the fields at the surface are hardly detectable.

The electric appliances in the household function under the same principle, i.e. at a distance of 30 cm, the EM fields are more than 100 times lower than the accepted limits for the general public. Moreover, in contrast to the electric fields that exist in the plugged wires even when there is no current flowing, the magnetic fields are produced only at the switching on of the appliance. Magnetic fields are not blocked by walls or other common materials. These fields vary greatly in flux density (70 T for a hairdryer or 0.1 T for a tape player).

The TV sets and VDU-s emit a wide spectrum of EM radiation ranging from X-rays to low frequency radiation. The emissions are both from front and rear of the monitor involving that way more people than the users. In these cases, thermal effects of the emitted radiation are negligible. Modern screens with liquid crystal displays have the advantage of lowering the immediate levels of EM radiation generated.

Domestic microwave ovens (see Table I.3.3.) function at very high power levels. A good appliance has low levels of leakage into the exterior; however, any microwave leakage decreases very rapidly with the distance from the oven.

Electromagnetic Radiation OutdoorsRadars are used by airports and harbors for navigation, by weather stations,

the military, etc. The emissions in this case are in the form of pulsed microwave signals. Many types of radar rotate or move up and down, diminishing this way the power density to which the public is exposed to.

Examples of security systems that involve the production of EM fields are the anti-theft systems, metal detectors or airport security systems. The most common technology uses in the first case pulsed fields with a specific frequency between 8-13 MHz to detect self-adhesive tags resonant to this frequency. The main magnetic fields exposures from such devices are directed mainly to the customers (short occupancy

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time), although some systems are installed near the exits. Metal detectors as well as the airport security systems set up strong magnetic fields of densities up to 100 T that are disturbed by the presence of a metal object. In the vicinity of the detectors, the field strengths are high, but not considered a health hazard.

The biggest exposure of public to EM fields on electrical transport comes from the on-board traction components rather than the overhead lines or the power rails. Intercity trains use 25 kV / 50 Hz overhead lines to supply power to the engines.

In these cases, the traction components are located in the separate power cars (up to 50 mT for workers), therefore passengers are exposed only to radiation from the on-train power supplies. Magnetic flux densities of several T are mostly common. In case of local and tube trains or trams, the motors are normally located underneath the floors of the passenger cars. Thus, passengers may receive at floor level magnetic fields of tens of T or more. However, the exposure of the upper body is much lower.

Mobile phones are low-power radio wave devices that transmit and receive signals from a network of fixed base stations. Their usage is at present extensively spread (only in the UK 72% of population have one and 10% of children 11-15 years old spend more than 45 minutes daily on calls). This communication system uses pulsed microwaves (see Table I.3.3.) to “carry” the voice information. Usual phones generate values of 25 V/m in the air close to the head, whereas at 1 to 5 m from it the fields will be less than 3 V/m. The use of a “hands free” set as a headphone device allows keeping the antenna at distance from the head, reducing this way the user’s exposure.

The action of EM fields from all man-made sources is cumulative.

Adverse Health Effects of Electromagnetic RadiationVery small electric currents exist in the human body even in the absence of

external man-made EM fields due to the chemical reactions that occur as part of the normal body function. Although in recent years the number of publications regarding the adverse effects of EM radiation on human health has increased, not all frequencies have been fully researched and not all questions have been fully answered. However, it is known that EM fields act on the human body in a different manner according to their intensity and their frequency. For example, ELF fields, if sufficiently intense, induce circulating currents in the body stimulating the nerves or muscles. Also, the heart, which is known to be electrically active, may be affected by such interference.

Biological tissues behave as efficient absorbers of EM energy with the result of local heating. Moreover, the depth of penetration depends on the type of tissue and decreases with the increase of EM wave frequency. Usually, the thermal and the non-thermal effects of radiation on humans are hard to separate. Nevertheless, the non-thermal effects are non-linear unlike the thermal ones. In case of mobile phone calls, for example, the brain’s temperature may rise with even a degree Celsius or more. In parallel, the epiphysis gland subjected to the repeated microwave vibrations has its

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capabilities diminished in the same alarming manner.Recent publications consider however that the biological human response is

likely to be a function of the fields within our bodies rather than the external fields of exposure, a theory that may be difficult to approach and assess. Nevertheless, it is believed that EM fields in excess have harmful effects on humans (children in residential settings and adults in occupational settings) raging from depression and fatigue to cancer. Other associated diseases may be headaches, Alzheimer’s disease, reproduction dysfunctions, cataracts, etc. The main cancers believed to relate to EM fields exposure are leukemia (power lines), nervous system tumors and, to a lesser extent, lymphoma among children, leukemia, nervous system tumors and breast cancer among adults. The entire landscape of EM interactions with us is complex and with certainty needs to be further researched.

REFERENCES1. Arashidani K., Yoshikawa M., Kawamoto T., Matsuno K., Kayam F., and

Kodama Y. (1996) Indoor pollution from heating. Indust. Health, 34, 205-15. 2. Badot, PM & Badot MJ (1995). Deperissement du pin d´Alep (P. halepensis

Miller) sous l´effect des embruns pollues. Ann.Sci. Univ. Fr.-Comté, Besacon, Biologie-Ecologie 3: 37-43.

3. Bennett, W.R. Jr. (1994). Health and Low-Frequency Electromagnetic Fields, Yale University Press.

4. Bregman, J. (1999) Environmental Impact Statements. Second edition, Boca Raton, CRC Press LLC, 248 p.

5. Brook G. A., Folkoff M. E., and Box E. O. (1983) A world model of soil carbon dioxide, Earth Surf. Proc. Landforms, S, 79-88.

6. Burr M. L., St.-Leger A. S., and Yamell J. W. G. (1981) Wheezing, dampness, and coal fires, Commun. Med.,. 3, 205-09.

7. Bussotti, F., Grossoni, P., Pantani, F. (1995) The role of marine salt ad surfactants in the decline of the Tyrrhenian coastal vegetation in Italy. Ann. Sci. For., 52: 251-261.

8. Bussotti, F., Bottacci, A.Grossoni, P., Mori, B. and Tani, C. (1997) Cytological and structural changes on Pinus pinea L. needles following the application of an anionic surfractant, Plant Cell Environ. 20: 513-520.

9. Cebotari, I. (1995) Ph. D. Thesis, Facultatea de Medicină, Bucureşti.10. Chadwick, P. (1998). Occupational Exposure to EMF: practical application

of NRPB guidelines. NRPB-R3401, Chilton:NRPB. 11. Chang, L.W., in L.W. Chang, ed. (1996) Toxicology of Metals, Lewis

Publisher, CRC Press, Boca Raton, Fla.12. Chang, L.W., in J.O. Nriagu, ed., (1979) The Biogeochemistry of Mercury in

the Environment, Elsevier Biomedical Press, Amsterdam, Netherlands, pp. 519-580.

71

13. Chang, L.W., in J.O. Nriagn, ed. (1981) Cadmium in the Environment, Part 2: Health Effects, John Wiley & Sons, New York, pp.783-840.

14. Chang, L.W., in L.W. Chang and R.S. Dyer, eds. (1995) Handbook of Neurotoxicology, Marcel Dekker, Inc., New York, pp. 143-170.

15. Chang, L.W. & Verity, M.A., in L.W. Chang and R.S. Dyer, eds. (1985) Handbook of Neurotoxicology, Marcel Dekker, Inc., New York, pp. 31-60.

16. Choi I. S. (1983) Delayed neurological squelae in carbon monoxide intoxication, Arch. Neurol. 40, 433-35.

17. Christian, G.D. (1994) “Analytical Chemistry”, Fifth Edition, Wiley, J. & Sons, New York.

18. Chu, N.S., Hochberg, F.H., Calne, D.B. & Olanow, C.W., in L.W. Chang and R.S. Dyer, eds. (1995) Handbook of Neurotoxicology, Marcel Dekker, Inc., New York, pp. 91-104.

19. Clarkson, T., Cranner, J., Sivulka, D. & co-workers (1984) Mercury Health Effects Update-Health Issue Assessment, U.S. EPA, Washington, D.C.

20. Clarkson, T.W., in Toxicity of Agents: Metals (Continuing Education Course #3), (1991) Society of Toxicology Meeting, Dallas, pp. 26-44.

21. Clement, R.E., Yang, P.W., Koester, C.J. (2001) Anal. Chem., 73, 2761-2790.22. Clements-Croome, D. (2004) Electromagnetic Environments and Health in

Buildings, Spon Press, London. 23. Committee on Evaluation of EPA Guidelines for Exposure to Naturally

Occurring Radioactive Materials Board on Radiation Effects Research Commission on Life Sciences, Evaluation of Guidelines for Exposures to Technologically Enhanced Naturally Occurring Radioactive Materials, National Academy Press, Washington DC, (1999).

24. Cory-Slechta, D.A. & Pounds, J.G., in L.W. Chang and R.S. Dyer, eds. (1995) Handbook of Neurotoxicology, Marcel Dekker, Inc., New York, pp. 61-90.

25. Criteria Air Contaminants (CAC). The 1995 National Emissions Inventory for Atmospheric Ammonia. Air Pollutant Emission. http://www.ec.gc.ca/pdb/ape/cape_home_e.cfm

26. De Matteo, B. (1986) Terminal Shock: The Health Hazards of Video Display Terminals, NC Press Ltd., Toronto.

27. Derwent R.G. and Davies T.J. (1994) Modelling the impact of NOx or hydrocarbon control on photochemical ozone in Europe. Atm. Env., 28, 2039-2052.

28. Eisler, R. (2000) Handbook of Chemical Risk Assessment: Health Hazards to Humans, Plants and Animals, CRC Press LLC.

29. Enke, C.G. (2001) The Art and Science of Chemical Analysis, John Wiley & Sons, New York.

72

30. Ethridge D. M., Pearman G, I., and Fraser P. J. (1992) Changes in tropospheric methane between 1841 and 1978 from a high accumulation rate Antarctic ice core, Tellus, 44B, 282-94.

31. Federal Trade Commission (1936) Docket No. 2825, Cushing Refining & Gasoline Co, June 19, 1936, Dept. of Justice files, 60-57-107, National Archives, Washington, DC.

32. Ferek R. J., Reid J. S., Hobbs P. V., Blake D. R., and Liousse C. (1998) Emission factors of hydrocarbons, halocarbons, trace gases, and particles from biomass burnng in Brazil. J. Geophys. Res. 103, 32, 107-18.

33. Finlayson-Pitts B. J. and Pitts, Jr. J. N. (1999) Chemistry of the Upper and Lower Atmosphere. Academic Press, San Diego.

34. Finucane, E.W. (Ed) (1998) Definitions, conversions and calculations for occupational safety and health professionals. Chapter 7: Ionizing & Non-ionizing Radiation 2nd ed. CRC Press LLC.

35. Framton M. W., Morrow P. E., Cox C., Gibb F. R., Speers D. M., and Utell M. J. (1991) Effects of nitrogen dioxide exposure on pulmonary function and airway reactivity in normal humans, Am. Rev. Respir. Disord.. 143, 522-7.

36. Garrec, J.P. and El Ayeb, N. (2001) Il problema degli aerosol marini inquinati in Francia e in Tunisia, Linea Ecologica, 33: 51-54.

37. Gold D. R. (1992) Indoor air pollution. Clin. Chest Med. 13, 215-229. 38. Goldstein I. F., Andrews L. R., and Hartel D. (1988) Assessment of human

exposure to nitrogen dioxide, carbon monoxide, and respirable particles in New York inner-city residences, Atmos. Environ. 22, 2127-39.

39. Hammond, P.B. & Bililes, R.P., in J. Doull, C.D. Klaassen and M.O. Amdur, eds. (1980) Casarett and Doull’s Toxicology, 2nd edition, Macmillan Publishing Corp., New York, pp. 409-467.

40. Harrison, R.M. (1999) Understanding Our Environment, Redwood Books Limited, Trowbridge.

41. Hastings, L., in L.W. Chang and R.S. Dyer, eds. (1995) Handbook of Neurotoxicology, Marcel Dekker, Inc., New York, pp. 171-212.

42. Hass, B.S., McDaniel, L.P. & Littlefield, N.S. (1996) Ann. Clin. Lab. Sci., 26, 18-30.

43. Hering S. V. and Friedlander S. K. (1982) Origins of aerosol sulphur size distributions in the Los Angeles Basin, Atmos. Environ. 16, 2647-56.

44. http://chrom.tutms.tut.ac.jp/JINNO/DATABASE/00alphabet.html 45. http://www.connex.ro 46. http://www.epa.gov/radiation/radionuclides/ 47. http://www.epa.gov/ttn/atw/hlthef/butadien.html 48. http://www.epa.gov/ttn/atw/hlthef/formalde.html 49. http://www.epa.gov/ttn/atw/hlthef/formalde.html 50. http://www.epa.gov/ttn/atw/hlthef/toluene.html

73

51. http://www.jmarcano.com/nociones/fresh1.html 52. http://www.romtelecom.ro/ 53. http://www.wellowner.org/awaterquality/radionuclides.shtml 54. http://www.visionlearning.com/library/ 55. Islam M. S. and Ulmer W. T. (1979) Threshold concentrations of SO 2 for

patients with oversensitivity of the bronchial system, Wissenschaft and Umwelt 1, 41-7.

56. Jacobson M. Z. (1997) Development and application of a new air pollution modelling system. Part II: Aerosol module structure and design, Atmos. Environ., 31, 131-44.

57. Jacobson M. Z. (2002) Atmospheric Pollution. History, Science and Regulation, pp 397, Cambridge University Press, United Kingdom.

58. John W., Wall S. M., Ondo J. L., and Winkimayr W. (1989) Acidic aerosol size distributions during SCAQS. Final Report for the California Air Resources Board under Contract No. A6-112-32.

59. Jones A. P. (1999) Indoor air quality and health, Atmos. Environ., 33, 4535-64.

60. Jones P. D. and Keigwin L. D. (1988) Evidence from Fram Strait (78°N) for early deglaciation.

61. Kasprzak, K.S., Waalkes, M.P. & Poirier, L.A. (1987) Trace Element Res., 21, 253-273.

62. Keeling C. D. and Whorf T. P. (2000) Atmospheric CO2 concentrations (ppmv) derived from in situ air samples collected at Mauna Loa Observatory, Hawaii. http://cdiac.esd.oml.gov/ftp/maunaloa-co2/maunaloa.co2.

63. Koester, C.J., Simonich, S.L., Esser, B.K. (2003) Anal. Chem., 75, 2813-2819.64. Kontush, A., Meyer, S., Finckh, B. et al. (1996) J. Bio. Chem., 271, pp 11106-

11112. 65. Kovarik B. (1998) Henry Pord, Charles Kettering and the "Fuel of the Future."

http://www.runet.edu/~wkovarik/papers/fuel.html.66. Kovarik B. (1999) Charles F. Kettering and the 1921 discovery of tetraethyl

lead in the context of technological alternatives. http://www.runet.edu/~wkovarik/papers/kettering.html.

67. Leaderer B. P, Stowe M., Li R., Sullivan J., Koutrakis P, Wolfson M., and Wiison W. (1993) Residential levels of particle and vapour phase acid associated with combustion sources. Proc. Sixth Intemat. Conf. Indoor Air Qual. Clim. Helsinki, Finland, pp. 147-52.

68. Leaderer B. P., Stolwijk J. A. J., Zagraniski R. T., and Qing-Shan M. (1984) A field study of indoor air contaminant levels associated with unvented combustion sources. Proc. 77th Ann. Meet. Air Pollut. Cont. Assoc. San Francisco, CA.

74

69. Lide D. R., ed. (1998) CRC Handbook of Chemistry and Physic, CRC Press, Inc., Boca Raton, FLA.

70. Liu, D.H.F., Liptak, B.G. (Eds) (1999) Environmental Engineers’ Handbook, Second Edition, CRC Press LLC.

71. LiY., Powers T. E., and Roth H. D. (1994) Random effects linear regression meta-analysis models with application to nitrogen dioxide health effects studies, J. Air Waste Manag. Assn.., 44, 261-70.

72. Lukiw, W.J. & McLachlan, D.R., in L.W. Chang and R. S. Dyer, eds. (1995) Handbook of Neurotoxicology, Marcel Dekker, Inc., New York, pp. 105-142.

73. Manahan, S.E. (2000) Environmental Chemistry, Seventh Edition, Boca Raton: CRC Press LLC.

74. Manahan, S.E. (2001) Fundamentals of Environmental Chemistry, Boca Raton: CRC Press LLC.

75. Maroni M. B., Seifert X. X., and Lindvall T. (1995) Indoor Air Quality -A Comprehensive Reference Book. eds. Elsevier, Amsterdam.

76. Mauna Loa Data Center (2001) Data for atmospheric trace gases, http://mloserv.mlo.hawaii.gov/.

77. Meyers, R.A. and Dittrich, D.K. (1999) Encyclopedia of Environmental Pollution and Cleanup, Volume 2, John Wiley and Sons, Inc., New York.

78. Midgley Jr., T. (August 1925) Tetraethyl lead poison hazards. Indust. Eng. Chem., 17 (8), 827.

79. Millán M.M., Artíñano B., Alonso L., Castro M., Fernandez-Patier R. & Goberna J. (1992) Meso-meteorological Cycles of Air Pollution in the Iberian Peninsula, (MECAPIP). Air Pollution Research Report 44, (EUR Nº 14834) CEC-DG XII/E-1, Rue de la Loi, 200, B-1040, Brussels.

80. Millan M.M., Sanz M.J. (1993) La contaminación atmosférica en la Comunidad Valenciana: Estado de conocimiento sobre los problemas en El Maestrazgo y Els Ports. Informes CEAM 93-1. Depósito Legal: V-1020-1993.

81. Millán M.M., Salvador R., Mantilla E., & Kallos G. (1997) Photo-oxidant Dynamics in the Western Mediterranean in Summer: Results from European Research Projects, J. Geophys. Res., 102, no. D7, 8811-8823.

82. Millán M.M., Mantilla, E., Salvador, R., Carratalá, A., Sanz, M.J., Alonso, L., Gangoiti, G., Navazo, M. (2000) Ozone cycles in the Western Mediterranean Basin: Interpretation of monitoring data in complex coastal terrain, J. Appl. Meteor., 39, 487-508.

83. Millán, M. M., Sanz, M.J., Salvador, R. & Mantilla, E. (2002) Atmospheric dynamics and ozone cycles related to nitrogen deposition in the western Mediterranean., Environmental Pollution, 118, 167-186.

84. Moore, G.S. (1999) Living with the Earth: Concepts in Environmental Health and Sciences, Boca Raton: Lewis Publishers.

75

85. Murley, L. (1995) Clean air around the world: national approaches to air pollution control, Brighton: International Union of Air Pollution Prevention and Environmental Protection Associates, pp 402.

86. Murphy, V.A., in M. Yasui, M.J. Strong, K. Ota, and M.A. Verity, eds. (1996) Mineral and Metal Neurotoxicology, CRC Press Inc., Boca Raton, Fla., pp. 229-242.

87. Ochiai, Ei-O. (1987) General Principles of the Biochemistry of the Elements. Plenum Press, New York.

88. Pilotto L. S., Douglas R. M., Atteweil R. G., and Wilson S. R. (1997) Respiratory effects associated with indoor nitrogen dioxide exposure in children, Int. J. Epidemial. 26, 788-96.

89. Qin Y. H., Zhang X. M., Jin H. Z., Liu Y. Q., Pan D. L., and Pan Z. J. (1993) Effects of indoor air pollution on respiratory illness of school children, Proc. Sixth Int. Conf. Indoor Air Qual. Clim., Helsinki, Finland, 477-82.

90. Richardson, S.D. (2001) Anal. Chem., 73, 2719-2734.91. Richardson, S.D. (2003) Anal. Chem., 73, 2831-2857.92. Rubinson, K.A., Rubinson, J.F. (2001) Análisis Instrumental, Pearson

Educación, Madrid. English manuscript; Instrumental análisis, Prentice (2000).

93. Rushton L. and Cameron K. (1999) Selected organic chemicals. In Air Pollution and Health, Holgate S. T., Samet J. M., Koren H. S., and Maynard R. L., eds., Academic Press, San Diego, pp. 813-38.

94. Rodier, J. (1984) L´analyse de l´eau. Eaux naturelles, residuaries, eau de mer. Dunod Borras, Paris.

95. Saenz, A. L., Stephens, R. W. B. (1986) Noise Pollution. Effects and Control, John Wiley & Sons, Chichester.

96. Samet J. M., Marbury M. C., and Spengler J. D. (1987) Health effects and sources of indoor air pollution: Part 1. Am. Rev. Resp. Dis. 136, 1486-1508.

97. Sanz, M.J. and Millán, M.M., (2000) Ozone in the Mediterranean Region: evidence of injury to vegetation. In: Innes, J.L., Oleskyn, J. (Eds.), Forest Dynamics in Heavily Polluted Regions CAB International, London, pp. 165-192.

98. Schwarzberg M. N. (1993) Carbon dioxide level as migraine threshold factor: Hypothesis and possible solutions, Med. Hypoth., 41, 35-6.

99. Sears, F., W., Zemansky, M., W., Young, H., D. (1976) University Physics, Addison-Wesley Publishing Company.

100. Seawright, A.A., Brown, A.W., Ng, J.C., and Hrdlicka, J., in P. Grandjean, ed. (1984) Biological Effects of Organolead Compounds, CRC Press, Inc., Boca Raton, Fla., pp. 177-206.

101. Smith, B. J., Peters, R. J., Owen, S. (1996) Acoustics and Noise Control, Addison Wesley Longman, Harlow, 344 pp.

76

102. Spengler J. D. (1993) Nitrogen dioxide and respiratory illnesses in infants. Am. Rev. Resp. Dis,. 148,1258-65.

103. Styblo, M., Delnomdedieu, M. & Thomas, D.J., in R.A. Goyer and M.G. Cherian, eds. (1995) Handbook of Experimental Pharmacology, Springer Verlag, New York, pp. 407-433.

104. Townshend, A. (Ed) (1995) Encyclopedia of Analytical Science, London: Academic Press.

105. Turco R. R (1997) Earth Vnder Siege, Oxford University Press, Oxford. 106. U.S. Environmental Protection Agency (U.S. EPA) (1978) Air quality criteria

for ozone and other photochemical oxidants. Report No. EPA-600/8-78-004. 107. U.S. Environmental Protection Agency (U.S. EPA) (1996) Air Quality

Criteria for Particulate Matter, Research Triangle Park, NC, National Center of Environmental Assessment-RTP Office, EPA/600/P -95/001aF-cf. 3 volumes. Available from NTIS, Springfield, VA, PB96- 168224.

108. U.S. Environmental Protection Agency (U.S. EPA) (1998) 1997 National Air Quality Status and Trends, U.S. Environmental Protection Agency, Office of Air and Radiation.

109. U.S. Environmental Protection Agency (2002) Integrated Risk Information System (IRIS) on Benzene. National Center for Environmental Assessment, Office of Research and Development, Washington, DC.

110. U.S. Public Health Service (U.S. PHS) (Sept. 1925) The use of tetraethyl lead gasoline in its relation to public health. Public Health Bulletin No. 163, Treasury Dept., Washington, DC.

111. U.S. Public Health Service (U.S. PHS) (March 30, 1959) Public health aspects of increasing tetraethyl lead content in motor fuel. Report on the Advisory Committee on Tetraethyl Lead to the Surgeon General, PHS publication No. 712, Washington, DC.

112. Venkataraman C. and Friedlander S. K. (1994) Size distributions of polycyclic aromatic hydrocarbons and elemental carbon. 2. Ambient measurements and effects of atmospheric processes. Environ. Sci. Technol,. 28, 563-72.

113. Verity, M.A., in M. Yasui, M.J. Strong, K. Ota and M.A. Verity, eds. (1996) Mineral and Metal Neurotoxicology, CRC Press, Inc., Boca Raton, Fla., pp. 159-168.

114. Von Berg, R. & Greenwood, M.R., in E. Merian, ed. (1991) Metals and Their Components in the Environment, VCH Publisher, Weinheim, Germany, pp. 1045-1088.

115. Weinstein, L.H. and A. W. Davison (2004) Fluorides in the environment. CABI Publishing, London, 287 p.

116. Wetterhahn, E.K. and Dudek, E.J. (1996) New J. Chem,. 23, pp. 199-203. 117. White, F.A. (1975) Our Acoustic Environment, John Wiley & Sons, New

York.

77