A pollutant is a waste material that pollutes air, water or soil. Three factors determine the severity of a
pollutant: its chemical nature, the concentration and the persistence. Some pollutants are biodegradable
and therefore will not persist in the environment in the long term.

Types of pollutants

Stock pollutants
Pollutants that the environment has little or no absorptive capacity are called stock pollutants (eg.
persistent synthetic chemicals, non-biodegradable plastics, and heavy metals). Stock pollutants
accumulate in the environment over time. The damage they cause increases as more pollutant is emitted,
and persists as the pollutant accumulates. Stock pollutants can create a burdon for future generations by
passing on damage that persists well after the benefits received from incurring that damage have been
forgotten.


Fund pollutants
Fund pollutants are those for which the environment has some absorptive capacity. Fund pollutants do not
accumulate in the environment unless the emission rate exceeds the receiving environment's absorptive
capacity (eg. carbon dioxide, which is absorbed by plants and oceans). Fund pollutants are not destroyed,
but rather converted into less harmful substances, or diluted/dispersed to non-harmful concentrations.


Pollution
Air pollution is the introduction of contaminants into an environment that causes instability, disorder, harm
or discomfort to the ecosystem i.e. physical systems or living organisms. Pollution can take the form of
chemical substances, or energy, such as noise, heat, or light energy. Pollutants, the elements of pollution,
can be foreign substances or energies, or naturally occurring; when naturally occurring, they are
considered contaminants when they exceed natural levels. Pollution is often classed as point source or
nonpoint source pollution. The Blacksmith Institute issues annually a list of the world's worst polluted
places. In the 2007 issues the ten top nominees are located in Azerbaijan, China, India, Peru, Russia,
Ukraine and Zambia.

Forms of pollution
The major forms of pollution are listed below along with the particular pollutants relevant to each of them:

Air pollution, the release of chemicals and particulates into the atmosphere. Common gaseous air
pollutants include carbon monoxide, sulfur dioxide, chlorofluorocarbons (CFCs) and nitrogen oxides
produced by industry and motor vehicles. Photochemical ozone and smog are created as nitrogen oxides
and hydrocarbons react to sunlight. Particulate matter, or fine dust is characterized by their micrometre size
PM10 to PM2.5.

Water pollution, by the release of waste products and contaminants into surface runoff into river drainage
systems, leaching into groundwater, liquid spills, wastewater discharges, eutrophication and littering.
Soil contamination occurs when chemicals are released by spill or underground leakage. Among the most
significant soil contaminants are hydrocarbons, heavy metals, MTBE[7], herbicides, pesticides and
chlorinated hydrocarbons.

Littering

Radioactive contamination
, resulting from 20th century activities in atomic physics, such as nuclear power
generation and nuclear weapons research, manufacture and deployment. (See alpha emitters and
actinides in the environment.)

Noise pollution, which encompasses roadway noise, aircraft noise, industrial noise as well as
high-intensity sonar.

Light pollution, includes light trespass, over-illumination and astronomical interference.

Visual pollution, which can refer to the presence of overhead power lines, motorway billboards, scarred
landforms (as from strip mining), open storage of trash or municipal solid waste.

Thermal pollution, is a temperature change in natural water bodies caused by human influence, such as
use of water as coolant in a power plant.


Source: Wikipedia
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