Landfills, heavy metal contamination source

Landfill leachate is a potential source of heavy metal contamination and a popular horror story in newspapers. Landfills concentrate wastes, the wastes are not always mixed thoroughly with soil, and soils have limits in their capacity to react. Landfills... 

Water supplies are closely monitored for heavy metals, because they tend to be very toxic. Major sources of heavy metal contamination include landfills, industries, agriculture, mining, and old water distribution systems. 

The automobile is also an indirect source of another heavy metal contaminant, chromium. Chromium compounds (such as Cr04 ) are used in chrome plating for bumpers and grills. This plating also requires the use of the cyanide ion (CN), another major pollutant. These contaminants used to be discharged directly into streams, but now they re either pretreated to reduce to a less-toxic form or precipitated (formed into a solid) and disposed of in landfills. 

Landfill leachate is an important point pollution source to water body, which contains DOM with a large number of unknown molecules that actively involve in biogeochemical and environmental processes (Chin et al. 1997). DOM not only plays an important role in freshwater systems for the mobility of toxic heavy metals and other pollutants but also may itself be a groundwater contaminant (Christensen etal. 1998). 

The relationship between water and the geosphere is twofold. The geosphere may be severely damaged by water pollution. This occurs, for example, when water pollutants produce contaminated sediments, such as those polluted by heavy metals or polychlorinated biphenyls. In some cases, the geosphere serves as a source of water pollutants. Examples include acids produced by exposed metal sulfides in the geosphere or synthetic chemicals improperly discarded in landfills. 

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