Water quality_1

Water quality_1 - ater Quality and Pollution What is...

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Unformatted text preview: ater Quality and Pollution What is pollution? Pollution is a degradation of quality, usually due to the presence of a substance (i.e., a pollutant or contaminant) However, pollution may exist even when no foreign substance is present Noise pollution Thermal pollution Cooling pond for power plant Infrared image of water cooling 24 million people in Bangladesh are drinking groundwater that contains arsenic in concentrations that exceed safe drinking water standards. Arsenic is toxic and carcinogenic. Most common disorder: keratosis Arsenic contamination in drinking water wells in Bangladesh Approx. 4.5 million tube wells in Bangladesh Widespread use of tube wells began in the 1980s after contamination of surface waters made a source of clean water necessary. Widespread arsenic contamination in groundwater not identified until early-mid 1990s. Shift from surface water to well water is credited with reducing infant mortality rate and allowed widespread irrigation and grain self-sufficiency. The arsenic occurs naturally from weathering of rocks. It is not from human activities. Hand-drilling a tube well When is water clean and when is it polluted? All naturally occurring waters contain many (if not most) of the elements in the periodic table. They are never pure H 2 O. Important concept is how high the concentration of a pollutant must be to have a discernible adverse effect. U.S. EPA establishes maximum contaminant levels (MCLs) for most known pollutants. Depending on the particular pollutant, MCLs are usually in the mg/L (ppm) or g/L (ppb) concentration range. Pollutant Regulation, Assessment, and Compliance in the US Federal Agencies-- US Environmental Protection Agency (EPA)-- Nuclear Regulatory Commission (NRC)-- US Geological Survey (USGS)...
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Water quality_1 - ater Quality and Pollution What is...

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