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Shallow groundwater mercury supply in a coastal plain stream

August 1, 2012

Fluvial methylmercury (MeHg) is attributed to methylation in up-gradient wetland areas. This hypothesis depends on efficient wetland-to-stream hydraulic transport under nonflood and flood conditions. Fluxes of water and dissolved (filtered) mercury (Hg) species (FMeHg and total Hg (FTHg)) were quantified in April and July of 2009 in a reach at McTier Creek, South Carolina to determine the relative importance of tributary surface water and shallow groundwater Hg transport from wetland/floodplain areas to the stream under nonflood conditions. The reach represented less than 6% of upstream main-channel distance and 2% of upstream basin area. Surface-water discharge increased within the reach by approximately 10%. Mean FMeHg and FTHg fluxes increased within the reach by 23–27% and 9–15%, respectively. Mass balances indicated that, under nonflood conditions, the primary supply of water, FMeHg, and FTHg within the reach (excluding upstream surface water influx) was groundwater discharge, rather than tributary transport from wetlands, in-stream MeHg production, or atmospheric Hg deposition. These results illustrate the importance of riparian wetland/floodplain areas as sources of fluvial MeHg and of groundwater Hg transport as a fundamental control on Hg supply to Coastal Plain streams.

Citation Information

Publication Year 2012
Title Shallow groundwater mercury supply in a coastal plain stream
DOI 10.1021/es301540g
Authors Paul M. Bradley, Celeste A. Journey, Mark A. Lowery, Mark E. Brigham, Douglas A. Burns, Daniel T. Button, Francis H. Chapelle, Michelle A. Lutz, Mark C. Marvin-DiPasquale, Karen Riva-Murray
Publication Type Article
Publication Subtype Journal Article
Series Title Environmental Science & Technology
Series Number
Index ID 70039322
Record Source USGS Publications Warehouse
USGS Organization South Atlantic Water Science Center

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