Mercury concentrations in water from an unconfined aquifer system, New Jersey coastal plain

Concentrations of total mercury (Hg) from 2 μg/L (the USEPA maximum contaminant level) to 72 μg/L in water from about 600 domestic wells in residential parts of eight counties in southern New Jersey have been reported by State and county agencies. The wells draw water from the areally extensive (7770 km²) unconfined Kirkwood–Cohansey aquifer system, in which background concentrations of Hg are about 0.01 μg/L or less. Hg is present in most aquifer materials at concentrations 0.1 μg/L did not correlate significantly with concentrations of the inorganic constituents. Hg_f concentrations near or exceeding 2 μg/L were found only in water from wells in areas with residential land use, but concentrations were at background levels in most water samples from undeveloped land. The spatial distribution of Hg-contaminated ground water appears to be locally and regionally heterogeneous; no extensive plumes of Hg contamination have yet been identified.