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.
WATER POLLUTION !
Water pollutants come from point and non-point sources.Their effects on aquatic systems largely
depend on whether polluted waters are standing (lakes and ponds) or flowing (rivers).
Standing systems are generally more susceptible ,
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.
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.
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 plants.
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.
Category:
WATER POLLUTION
| 0 Comments