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The Common Sense
Environmental Fund
Water Pollution
/ Groundwater Pollution /
Ocean Pollution
Water/Marine
Water
is the resource that covers almost three-quarters of the planet, and
upon which all life depends. Throughout the history of the natural
world, water sources have been the centers of life, providing habitat
and sustenance for animals and plants alike.
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because of slow turnover. The major water pollutants
are organic nutrients, inorganic nutrients, infectious agents, toxic
organics, toxic inorganics, sediment and heat. Organic nutrients come
from feedlots, municipal sewage treatment plants, and industry.
They promote growth of natural populations of aquatic bacteria.
Bacterial decomposition of organic materials results in declines in
dissolved oxygen, with dire effects on other oxygen-requiring organisms.
Two inorganic plant nutrients of major concern are nitrogen and
phosphorus. They come primarily from septic tanks, barnyards,
heavily fertilized crops, and sewage treatment plants, and cause
excessive plant growth that clogs navigable waterways. Bacterial
decay of plants in the fall result in a drop in dissolved oxygen, which
may suffocate fish and other organisms.
Water may contain pathogenic bacteria, viruses, protozoans, parasites
(infectious agents). Untreated or improperly treated sewage,
animal wastes, meat-packing wastes, and some wild species are the major
sources. Waterborne infectious diseases present a special problem
in developing nations with poorly developed sewage treatment facilities.
Toxic organic pollutants include a large number of chemicals, such as
pesticides and PCBs, many of which are nonbiodegradable or slowly
degraded, biologically magnified and carcinogenic.
Toxic inorganic pollutants include a wide range of chemicals, such as
metals and salts, from a wide array of sources. Mercury is a
particularly troublesome pollutant because it is converted into methyl
and dimethyl mercury in a aquatic ecosystem by aerobic bacteria.
These forms are more toxic than inorganic mercury. Methyl mercury
is biologically magnified in the food chain.
Sediment, the leading water pollutant in the United States, is a
by-product of erosion resulting from poorly managed timber cutting,
agriculture, ranching, mining and construction.
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Sediment destroys spawning and feeding
grounds for fish, reduces fish and shellfish populations, destroys
pools used for resting, smothers eggs and fry, fills in lakes and
streams, and decreases light penetration, thus endangering aquatic
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Thermal pollution refers to the
heating or cooling of water, both of which drastically alter
biota in a body of water. Large quantities of heat can
kill heat-sensitive organisms and harm organisms dependent on
the aquatic ecosystem.
The
concentration of many pollutants in groundwater is often higher
than that in the most contaminated surface water supplies. Many
of the chemicals are tasteless and odorless at concentrations
believed to pose a threat to human health. The major groundwater
pollutants are chlorides, nitrates, heavy metals, and toxic
organics.
Since groundwater usually moves
slowly through an aquifer, it may take years for pollution to show
up in areas adjacent to sources of contamination. Once an aquifer
is contaminated the pollutants may remain for centuries.
Ocean
Pollution
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The oceans receive
pollutants from many sources. Oil pollutions is one of the more
serious problems. About half of the oil that contaminates the
ocean comes from human sources: oil well blowouts, tanker spills,
and inland disposal of oil. Oil harms many organisms, especially
if a spill occurs near an estuarine zone. |
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It may take two to ten years for aquatic life to recover from a spill.
Thanks to public outcry and stricter controls, the number of oil spills
has decreased substantially, although the problem is far from solved.
Plastic pollution has also become a major problem throughout the world.
Plastic nets, plastic garbage, and plastic medical wastes are killing
millions of marine mammals, turtles, and fish. Animals may become
tangles in the plastic debris or may eat it and die. Because of public
outcry, many governments have banned the dumping of plastics in oceans.
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