, Volume 40, Issue 2–3, pp 249–265 | Cite as

Behavior of mercury in the Patuxent River estuary

  • J.M. Benoit
  • C.C. Gilmour*
  • R.P. Mason
  • G.S. Riedel
  • G.F. Riedel


An overview of a comprehensive study of the behavior and fate of mercury in the estuarine Patuxent River is presented. Total Hg (HgT) and methylmercury (MeHg) exhibited weakly non-conservative behavior in the estuary. Total Hg concentrations ranged from 6 ng L-1 in the upper reaches of the sub-urbanized tidal freshwater river to <0.5 ng L-1 in the mesohaline lower estuary. Filterable (0.2 µm) HgT ranged from 0.2 to 1.5 ng L-1. On average, MeHg accounted for <5% of unfiltered HgT and <2% of filterable HgT. Dissolved gaseous section Hg (DGHg) concentrations were highest (up to 150 pg L-1) in the summer in the mesohaline, but were not well correlated with primary production or chlorophyll a, demonstrating the complex nature of Hg0 formation and cycling in an estuarine environment. Organic matter content appeared to control the HgT content of sediments, while MeHg in sediments was positively correlated with HgT and organic matter, and negatively correlated with sulfide. MeHg in sediments was low (0.1 to 0.5% of HgT). Preliminary findings suggest that net MeHg production within sediments exceeds net accumulation. Although HgT in pore waters increased with increasing sulfide, bulk MeHg concentrations decreased. The concentration of MeHg in sediments was not related to the concentration of HgT in pore waters. These observations support the hypothesis that sulfide affects the speciation and therefore bioavailability of dissolved and/or solid-phase Hg for methylation. Comparison with other ecosystems, and the negative correlation between pore water sulfide and sediment MeHg, suggest that sulfide limits production and accumulation of MeHg in this system.

estuaries mercury methylmercury sediment 


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Copyright information

© Kluwer Academic Publishers 1998

Authors and Affiliations

  • J.M. Benoit
  • C.C. Gilmour*
  • R.P. Mason
  • G.S. Riedel
  • G.F. Riedel

There are no affiliations available

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