Five trace elements with human-health concerns were detected at high concentrations: arsenic, boron, molybdenum, strontium, and vanadium. Chromium and fluoride were detected at moderate concentrations.
Uranium, arsenic, and nitrate were the inorganic constituents that were most frequently detected at high concentrations, mostly in shallower wells. High and moderate concentrations of arsenic were detected in deeper wells.
Arsenic and boron were the trace elements that most frequently occurred at high concentrations. Fumigants (pesticides) were detected at high concentrations in 3% of the primary aquifers. Herbicides and insecticides were detected at low concentrations.
Recent study indicating inorganic constituents as the primary items of concern in this area. Chemical and mineralogical compositions of the aquifer rocks probably explain variation among localities here.
Trace elements are inorganic chemicals occurring in small amounts in nature. This web site of the National Water Quality Assessment links to U.S. data, publications, news, and other sites on trace metals, metalloids and radionuclides in water.
Results (*.pdf) of a 1998 targeted reconnaissance survey on the sources of radium, polonium, and lead radionuclides, data collection and laboratory methods, existing occurrences in drinking water, risk assessments, and compliance monitoring.
Contaminants from mines move more easily from ore materials and mine waste piles to surrounding estuaries and living organisms when water moves through the mine site. Geochemical results shown here will help people mitigate the negative effects.