Hydraulic and biochemical gradients limit wetland mercury supply to an Adirondack stream

SOJ Aquatic Research
By: , and 

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Abstract

Net fluxes (change between upstream and downstream margins) for water, methylmercury (MeHg), total mercury (THg), dissolved organic carbon (DOC), and chloride (Cl) were assessed twice in an Adirondack stream reach (Sixmile Brook, USA), to test the hypothesized importance of wetland-stream hydraulic and chemical gradients as fundamental controls on fluvial mercury (Hg) supply. The 500 m study reach represented less than 4% of total upstream basin area. During a snowmelt high-flow event in May 2009 surface water, DOC, and chloride fluxes increased by 7.1±1.3%, 8.0±1.3%, and 9.0±1.3%, respectively, within the reach, demonstrating that the adjacent wetlands are important sources of water and solutes to the stream. However, shallow groundwater Hg concentrations lower than in the surface water limited groundwater-surface water Hg exchange and no significant changes in Hg (filtered MeHg and THg) fluxes were observed within the reach despite the favorable hydraulic gradient. In August 2009, the lack of significant wetland-stream hydraulic gradient resulted in no net flux of water or solutes (MeHg, THg, DOC, or Cl) within the reach. The results are consistent with the wetland-Hg-source hypothesis and indicate that hydraulic and chemical gradient (direction and magnitude) interactions are fundamental controls on the supply of wetland Hg to the stream.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Hydraulic and biochemical gradients limit wetland mercury supply to an Adirondack stream
Series title SOJ Aquatic Research
Year Published 2016
Language English
Publisher Symbiosis Group
Contributing office(s) South Atlantic Water Science Center, Toxic Substances Hydrology Program
Description 9 p.
Country United States
State New York, South Carolina
Other Geospatial Fishing Brook, McTier Creek basin, Sixmile Brook
Online Only (Y/N) N
Additional Online Files (Y/N) N