ELEMENTAL POISONING IN RELATION TO

TOXICITY OF WATER.JIGYASA SHARMA

ELEMENTS• Elements occur naturally in the environmental but due to industrial

revolution via technological advancement, Elements concentrations in the environment are becoming increasingly high.

• Elements occurrence in the environment has become an environmental concern because the globe is said to be experiencing a silent epidemic of environment poisoning from the ever increasing amounts of elements released into the biosphere.

ELEMENTAL POISONING• Elemental toxicity or elemental poisoning is the toxic effect of certain

elements in certain forms and doses on life. Some elements are toxic when they form poisonous soluble compounds.

• Elemental poisoning causes elemental pollution.• Certain elements have no biological role, i.e. are not essential

minerals, or are toxic when in a certain form.• Like :- lead, mercury, chromium, cobalt etc.

POLLUTION• WHAT IS POLLUTION?The presence in or introduction into the environment of a substance which has harmful or poisonous effects.Pollution can take the form of chemical substances or energy, such as noise, heat or light. Pollutants, the components of pollution, can be either foreign substances/energies or naturally occurring contaminants.

WATER POLLUTION• Water pollution is the contamination of water bodies

(e.g. lakes, rivers, oceans, aquifers and groundwater). • This form of environmental degradation occurs when

pollutants are directly or indirectly discharged into water bodies without adequate treatment to remove harmful compounds.

• Water pollution affects the entire biosphere – plants and organisms living in these bodies of water. In almost all cases the effect is damaging not only to individual species and population, but also to the natural biological communities.

HEAVY METALS• Heavy metals are those metal of relatively high density, or high

relative atomic weight. • Heavy metal can include elements lighter than carbon and can exclude

some of the heaviest metals.

COMMON HEAVY METALS CAUSING AQUEOUS POLLUTION

• Cadmium • Lead• Mercury• Aluminum• Antimony• Arsenic• Zinc and Copper• Nickel• Tin• Uranium

Sources of heavy metals pollution• Primary sources of heavy metals are point sources:

- Mines - Foundries - Smelters - Coal-burning power plants - Diffuse sources (combustion by-products

and vehicle emissions)• Waste-derived fuels are especially prone to contain heavy

metals, so heavy metals are a concern in consideration of waste as fuel.

• Electronic waste is also a significant source of heavy metal contaminants

Lead Aqueous Pollution

• Lead is a highly toxic trace element with no recognized biological requirement in organisms. Moreover, there may be no concentration threshold for Pb in humans or other mammals. The concentration of the metal has been substantially elevated by industrial release.

• The relative environmental Pb contamination is unparalleled among the elements and most of it dispersed as an environmental pollutant on a global scale.

• Pb is therefore very ubiquitous (found in several places), being found in the atmosphere, soil, water, plant, foods and sediments.

Lead Aqueous Pollution

• Lead in water: Lead has the tendency to form compounds of low solubility with major anions found in natural water.

• Some of them are found in an undissolved form (colloidal particles or larger undissolved particles of PbCO3, PbO and Pb(OH)2.

• The ration of Pb in suspended solids to Pb in dissolve form has been found to increase from 4:1 to 27:1 in urban streams, implying increased pollution.

• Consumption of such untreated water may lead to Lead Poisoning.

Lead Aqueous Pollution

• Health EffectsInfants and children: Delays in physical or mental development; children could show slight deficits in attention span and learning abilities.Adults: Kidney problems; high blood pressure

• Sources of contaminationCorrosion of household plumbing systems, erosion of natural deposits. Industrial sources such as lead mining, smelting and coal combustion, the use of lead-based paint and lead containing pipes in water supply systems.

Arsenic Aqueous Pollution• Arsenic contamination of groundwater is often due to naturally

occurring high concentrations of arsenic in deeper levels of ground water

• Its sources are geochemical processes, mining activities • Industrial and manufacturing processes.• through the dissolution of minerals and ores, and as a result of

erosion from local rocks.• It can causes:• Irritation of the stomach and intestines• Red and white blood cells decreased production, skin changes

and lung irritation

Cadmium Aqueous Pollution

• Maximum contaminant level for cadmium is 0.005 mg/L or 5 ppb.• Cadmium applications- including electroplating and the manufacture

of batteries.• Contaminated foodstuffs can result in emphysema, renal failure,

cardiovascular disease, and perhaps cancer.

Mercury Aqueous Pollution

• largest emitters  cement plants power plants gold mining, and industrial boilers in • In areas of mercury contamination, larger and older fish tend to

have higher levels of mercury.• Minamata disease is a neurological syndrome caused by

severe mercury poisoning by polluted water. Symptoms include ataxia, numbness in the hands and feet, general muscle weakness, narrowing of the field of vision, and damage to hearing and speech.

Nickel Aqueous PollutionMetallic nickel and some other nickel compounds are teratogenic and carcinogenic to mammals. Nickel concentrations in plants are usually 1 μg/g, and concentrations above 50 μg/g are toxic.

Effects of nickel:• Increased red blood cells (cancer)• Increased protein in the urine• Chronic bronchitis• Reduced lung function• Stomach aches• Cancer of the lungs

Uranium Aqueous Pollution

• Uranium is a naturally and commonly occurring radioactive element and found in water coming from power plants causing uranium contained water pollution

• Uranium poisoning causes birth abnormalities including physical deformities, neurological and mental disorders.

Zinc Aqueous Pollution

• Zinc in water (from wastewater of industrial plants) increases the acidity of waters. Some fish can accumulate Zn in their bodies, when found in zinc contaminated waterways. Zinc in fish can bio-magnify and eater in food chain.

• Insoluble zinc in soils can contaminate groundwater. Large concentrations of zinc in soils of farmland pose health threat to animals and plants also (apart from groundwater contamination).

• Zn can lead to acute gastrointestinal and respiratory damages and acute heart, brain and kidney damages, when they are in polluted aqueous form.

Chromium Aqueous Pollution

• Chromium is not known to accumulate in the bodies of fish, but high concentrations of chromium, due to the disposal of metal products in surface waters, can damage the gills of fish that swim near the point of disposal.

• In animals chromium can cause respiratory problems, a lower ability to fight disease, birth defects, infertility and tumour formation.

• Chromium(VI) is mainly toxic to organisms

METHODS TO PURIFY WATER FROM ELEMENTAL POLLUTION

• COMMONLY USED METHODS - Chemical precipitation - Biosorption - Ion exchange - Reverse osmosis

- Solvent extraction 

• Reverse Osmosis:  It is a process in which heavy metals are separated by a semi-

permeable membrane at a pressure greater than osmotic pressure caused by the dissolved solids in wastewater.

• Ions exchange:In this process, metal ions from dilute solutions are exchanged with ions held by electrostatic forces on the exchange resin.Different type of ion exchange resins are used for every metal like Lead

: carboxylic resin

• Chemical Precipitation: Precipitation of metals is achieved by the addition of coagulants such

as alum, lime, iron salts and other organic polymers. The large amount of sludge containing toxic compounds produced during the process is the main disadvantage.

• Biosorption

The biosorption process involves a solid phase (biological material) and a liquid phase (solvent, normally water) containing a dissolved species to be absorbed. The degree of sorbent affinity for the sorbate determines its distribution between the solid and liquid phases.Many algae have immense capability to absorb metals, and there is considerable potential for using them to treat wastewaters

• Zeolites1. Zeolites are nature's powerful detoxifiers that are so strong they even

binds all those heavy metals from the food and water we ingest. 2. Natural zeolites can safely remove heavy metals such as mercury,

cadmium, lead, arsenic, aluminum, and tin, while also removing radioactive metals like cesium and Strontium-90.

3. Zeolites are  microporous,  alum inosilicate, minerals  commonly used as commercial adsorbents.

METAL DETECTION TECHNIQUES

The analytical methods commonly used in estimation of heavy metals in water and waste waters are: • Inductively coupled plasma analyser (ICP) • Atomic absorption spectrophotometry (AAS)• Colorimetric methods • Polarographic estimation • Ion Selective Electrodes (ISE)

RESULT

• Surface/ground water contamination through toxic metals is a problem since long. Many countries in the world have experienced menace of metal pollution in water and large number of people have been affected. The governments of the countries are trying to solve it and it maybe cured someday.