| Ground water vulnerability to contamination is regarded as the "tendency or likelihood for contaminants to exceed a threshold value (usually, Maximum Contaminant Level (MCL)) in a ground water system of the uppermost aquifer under existing land use, hydrogeochemical, and microbial conditions." On a regional scale, major ground water contaminant classes include nitrates, pesticides, and heavy metals (arsenic, cadmium, chromium, lead, and mercury). Determining where the ground water is at risk on a regional scale is crucial for making good management decisions on issues such as land uses, water treatment strategies, etc. Traditionally, ground water vulnerability assessments have concentrated on nitrates and pesticides. Heavy metals have not been assessed for their potential to contaminate ground water from a variety of sources, which that include natural sources and anthropogenic sources in agriculture, mining, residential, industrial and commercial land uses. A sound understanding of the aquifer vulnerability cannot be gained unless all the major contaminant classes, nitrates, pesticides, and heavy metals, are analyzed. The necessity to analyze aquifer vulnerability to heavy metals is further strengthened by the fact that heavy metals have the lowest MCLs, indicating high toxicity to human health and safety.; The proposed research consists of three parts. The first part of the proposed research involved development of better strategies for understanding ground water vulnerability to heavy metal contamination. This involves developing a methodology that can quantify the aquifer vulnerability to heavy metal contamination as well as give better insight into the factors influencing the aquifer vulnerability to heavy metal contamination. The second part of the research involved using the develop approach to assess the arsenic contamination of ground waters across the conterminous United States. The third part of the proposed research utilized the developed aquifer vulnerability assessment techniques to address some water policy issues. One such issue was addressed is to understand the aquifer sustainability from the ground water quality perspective. |
