Sunday, March 11, 2012

Crimes Against Nature by Paul Engleman

There are many causes of water pollution – general environmental conditions like overpopulation, individual incidents like oil spills, specific pathogens in sewage or fertilizer. And there are different categories: point source pollution, such as from a pipe at an industrial plant, and nonpoint source pollution, in which contaminants reach waterways through runoff, soil saturation, groundwater, and rainfall. Because water problems are so local, with so many reasons behind them, there is no single solution. Here are 12 common causes of pollution to consider.
King River, Australia

Mining can contribute to water pollution in a variety of ways – and not just when a containment dam holding pools of mine slurry sustains a breach. Rainwater can wash tailings (mine waste) into nearby bodies of water, and leach metals and sulfur compounds from rocks that are exposed during the excavation process. In gold mining, cyanide used to extract gold from ore often leaks into the water table, contaminating groundwater. A classic example of a body of water polluted by mining is the King River, in an area where copper was mined for more than a century. Although mining was curtailed in 1995, its effects continue as a result of discarded tailings and dissolved metals still present in the river. 
Niger Delta, Nigeria

Oil spills contaminate anything on the water’s surface, and kill plants below the surface by blocking sunlight. Fish and wildlife experience increased mortality rates, either from direct exposure or from eating contaminated invertebrates. It is estimated that the Niger Delta, on the west coast of Africa – home to more than 600 oil fields – experiences the equivalent of the Exxon Valdez oil spill every year. The spills can come from leaking terminals, pipes, pumping stations, and oil platforms. Shell, which is reportedly working in partnership with the Nigerian government, says that 98 percent of the spills are caused by vandalism or theft, and a minimal amount is related to infrastructural issues. 
Chesapeake Bay, North Carolina, USA

Nutrients may sound good, but excessive amounts of those like nitrogen and phosphorous can wreak havoc on coastal ecosystems. By elevating algae levels and causing hypoxia – lack of oxygen – they can result in widespread destruction of fish and other aquatic life. The nutrients reach the water through fertilizer runoff and sewage discharge as well as air pollution, and lead to overgrowths of toxic algae called red tides or brown tides. Zooplankton eat the algae, and the toxins work their way up the food chain, reaching humans through shellfish. When the overgrowths die, the algae decomposes, creating severe hypoxic conditions called dead zones. In 1997, several Chesapeake Bay tidal creeks experienced an outbreak of Pfiesteria, a toxin-producing pathogen that caused a massive fish kill as well as human health problems. 

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