Pollution

What is Pollution ?Pollution is the introduction of contaminants into the natural

environment that cause adverse change. 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.

Pollution is often classed as point source or nonpoint source

pollution

INDEX• Air pollution• Water pollution• Land pollution• Global Warming

Air PollutionSome air pollutants that are released into the atmosphere by man-

made activities pose environmental and health risks directly. These

primary pollutants include carbon monoxide, particulate

matter, nitrogen oxides and lead, emitted from exhausts of road

vehicles. Additional impacts, however, result from the conversion of

primary pollutants by a complex series of chemical reactions in the

atmosphere, to secondary pollutants. Since much of the pollutant

chemistry is driven by the presence of sunlight, the secondary

products are commonly referred to as photochemical pollutants.

Reactions in Air PollutionA well-known secondary photochemical pollutant is ozone (O3). Its

formation results from the sunlight-initiated oxidation (reaction with

oxygen) of volatile organic compounds (VOCs) such as benzene in

the presence of nitrogen oxides(NOx), mostly nitric oxide (NO) and

nitrogen dioxide (NO2). Once formed, ozone is scavenged by NO,

and in the absence of other competing reactions, a "photo

stationary state" is formed where concentrations of NO, NO2 and

O3 are all inter-related.

Air Pollution in Pictures

Water PollutionWater pollution occurs when undesirable foreign substances are

introduced into natural water. The substances may be chemical or

biological in nature. Common pollutants include human or animal

waste; disease-producing organisms; radioactive materials;

toxic metals such as lead or mercury; agricultural chemicals such as

pesticides, herbicides, or fertilizers; acid rain ; and high-temperature

water discharged from power plants, often called "thermal

pollution." Pollutants in water are dangerous for human or animal

consumption and harm crops. High temperatures may cause algae

to grow rapidly, rendering water unfit for consumption.

Reactions in Water Pollution

Pollutants in water are commonly measured and reported as parts

per million (ppm) or parts per billion (ppb). A solution that contains 2

grams(0.071 ounces) of lead in 1 million grams (2,205 pounds) ofwater (1,000 liters, or 264.2 gallons) is a 2 ppm solution. A 1 ppb

solution of calcium contains 1 gram (0.036 ounces) of calcium in 1

billion grams (2,205,000 pounds) of water. A concentration of 1 ppm

is the same as 1 milligram(3.6 × 10 −5 ounces) per liter.

Acid rain is a widespread term used to describe all forms of acid

precipitation (rain, snow, hail, fog, etc.). Atmospheric pollutants,

particularly oxides of sulphur and nitrogen, can cause precipitation

to become more acidic when converted to sulphuric and nitric acids, hence the term acid rain. Acid deposition, acid rain and

acid precipitation all relate to the chemistry of air pollution and

moisture in the atmosphere.

Water Pollution in Pictures

Land PollutionLand pollution is contaminating the land surface of the earth by

dumping waste. Human beings take part in making land pollution

Some examples are:

Soil Pollution – mainly due to chemicals in herbicides (weed killers)

and pesticides (poisons which kill insects and other invertebrate

pests).

Waste Disposal – waste threatens the health of people in residential

areas. It encourages household pests and turns urban areas intounsightly, dirty and unhealthy places to live in.

Reactions in Land Pollution

Modern fertilizer consists of varying amounts of nitrogen (N),

phosphorus (P) and potassium (K). These three are believed to be

essential for plants to grow, (below, I’ll discuss why NPK may not be

as necessary as we think.), and are extracted from the soil with

each harvest.

This is why farmers spread fertilizer on their fields, to replace the

nutrients lost. It’s certainly not the ideal and sustainable way to farm, but it’s thought to be the most efficient for large-scale farms.

Strategies like crop rotation and allowing large fields to rest would

cut too deep into profits that are based on quantity, opposed to

quality.

Land Pollution in Pictures

Global WarmingGlobal warming is the unequivocal and continuing rise in the

average temperature of Earth's climate system. Since 1971, 90% of

the increased energy has been stored in the oceans, mostly in the 0

to 700m region.

Since the early 20th century, the global air and sea surface

temperature has increased about 0.8 °C (1.4 °F), with about two-

thirds of the increase occurring since 1980. Each of the last threedecades has been successively warmer at the Earth's surface than

any preceding decade since 1850.

The greenhouse effect is the process by

which absorption and emission of infrared radiation by gases in a

planet's atmosphere warm its lower atmosphere and surface. It was

proposed by Joseph Fourier in 1824, discovered in 1860 by JohnTyndall, was first investigated quantitatively by Svante Arrhenius in

1896, and was developed in the 1930s through 1960s by Guy

Stewart Callendar

Global Warming in Pictures