Water Resources Research Act Program

Details for Project ID 2011NH141B

Arsenic chemical dynamics in NH groundwater reservoirs: Insights from temporal variability in multi-element signatures of statewide samples

Institute: New Hampshire
Year Established: 2011 Start Date: 2011-03-01 End Date: 2014-02-28
Total Federal Funds: $32,134 Total Non-Federal Funds: $79,613

Principal Investigators: Julia Bryce

Abstract: Several studies have documented high levels of arsenic, a known human health contaminant, in New Hampshire public and private groundwater wells, well in excess of the EPA-designated maximum contaminant level. Though high levels of arsenic may be attributed to both anthropogenic and natural sources, these studies taken together identify several key factors that control arsenic abundance in New Hampshires groundwater and suggest that the causes of high abundances across the state are generally attributable to local geological and geochemical factors. The work outlined in this proposal is designed to enhance understanding of natural controls on the presence of arsenic, a known human health contaminant, in groundwater. To elucidate the geochemical mechanisms responsible for cycling arsenic through groundwater, we will also measure aqueous abundances of iron and lead, a second regulated contaminant. Our primary targets are ~900 samples collected between 2003 and 2006 provided by J. Ayotte. We propose to complement the baseline samples for this work by resampling a subset (> 15%) of the groundwater wells to provide a perspective on how the abundance of contaminants changes over time. We will also carry out leaching experiments on two metasedimentary units found to contain a proportionately high number of groundwater wells with elevated arsenic contents (Montgomery et al., USGS fact sheet, 2003). The proposed research activities build upon earlier NH-based studies in four key ways: 1) expanding the time windows over which arsenic measurements are made in NH groundwaters; 2) expanding the geographical coverage of examining groundwater arsenic contents; 3) carrying out mineral-specific leaching experiments to enhance the role of specific mineral phases (sulfides + oxyhydroxides) in mobilizing arsenic into and adsorbing arsenic from NH groundwaters, and 4) carry out arsenic analyses in companion with other metals (namely iron and lead) to elucidate the role of natural phases in all three of these metals. The project supports two students and the development of new analytical techniques in new laboratories at the University of New Hampshire.