EAS446lec17

EAS446lec17 - EAS 44600 Groundwater Hydrology Lecture 17:...

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EAS 44600 Groundwater Hydrology Lecture 17: Contaminant Hydrology 1 Dr. Pengfei Zhang Types of Groundwater Contaminants A wide variety of contaminants have been found in groundwater. These include inorganic cations (e.g., heavy metals), inorganic anions (e.g., nitrate, phosphate, and sulfate), organic compounds (e.g., chlorinated solvents), radionuclides, and pathogenic bacteria and viruses (Table 17-1). Most of these contaminants will dissolve in groundwater to some degree. The inorganic cations and anions exist in a dissolved form in groundwater. Some of the organic compounds, however, are only slightly soluble in groundwater and will exist in both a dissolved form and a non-aqueous phase liquid (NAPL) form. Radionuclides and pathogenic bacteria and viruses are colloidal-size particles and will migrate in the porous media through the large pores or fractures (the so-called preferential flow paths ). Drinking Water Standards Under the Safe Drinking Water Act and its amendments, the United States Environmental Protection Agency (USEPA) has been directed by Congress to establish maximum contaminant-level goals (MCLGs) and maximum contaminant levels (MCLs) for drinking water. A maximum contaminant-level goal is a non-enforceable goal set at a level to prevent known or anticipated adverse health effects with a wide margin of safety. The MGLG for a carcinogen is zero. Maximum contaminant levels are enforceable standards that are set as close as feasible to the MCLGs, taking into account water-treatment technologies and cost. The
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This note was uploaded on 12/29/2010 for the course EAS 44600 taught by Professor Pengfeizhang during the Spring '10 term at CUNY City.

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EAS446lec17 - EAS 44600 Groundwater Hydrology Lecture 17:...

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