Natural Sources of Arsenic in Minnesota Groundwater
Arsenic concentrations in domestic well-water throughout large regions of Minnesota exceed the public drinking-water standard set by the U.S. Environmental Protection Agency. The frequency of arsenic contamination in domestic wells is a serious and widespread public-health concern; long-term exposure to arsenic is toxic to humans, even at extremely low concentrations. Although the Minnesota well code now requires that each new potable water-supply well be tested for arsenic, the information can come only after the well has been drilled. Although homeowners can purchase arsenic-removal systems, they are expensive, require maintenance, and do not provide alarms for high arsenic concentrations or system failure. It would be preferable if wells could be placed where the risk of arsenic contamination of groundwater is known to be low. This article summarizes the authors collaboration with the U.S. Geological Survey, the Minnesota Geological Survey, and the Minnesota Department of Natural Resources to address the natural sources of arsenic in Minnesota groundwater. The goal of the collaboration is to share resources, integrate existing knowledge and databases, and collect novel measurements to identify sources of arsenic and the distribution of those sources in Minnesota groundwater.
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