Legacy source of mercury in an urban stream-wetland ecosystem in central North Carolina, USA

Chemosphere. 2015 Nov;138:960-5. doi: 10.1016/j.chemosphere.2014.12.038. Epub 2015 Jan 7.

Abstract

In the United States, aquatic mercury contamination originates from point and non-point sources to watersheds. Here, we studied the contribution of mercury in urban runoff derived from historically contaminated soils and the subsequent production of methylmercury in a stream-wetland complex (Durham, North Carolina), the receiving water of this runoff. Our results demonstrated that the mercury originated from the leachate of grass-covered athletic fields. A fraction of mercury in this soil existed as phenylmercury, suggesting that mercurial anti-fungal compounds were historically applied to this soil. Further downstream in the anaerobic sediments of the stream-wetland complex, a fraction (up to 9%) of mercury was converted to methylmercury, the bioaccumulative form of the metal. Importantly, the concentrations of total mercury and methylmercury were reduced to background levels within the stream-wetland complex. Overall, this work provides an example of a legacy source of mercury that should be considered in urban watershed models and watershed management.

Keywords: Fungicide; Mercury; Methylmercury; Phenylmercury; Urban runoff; Wetland.

MeSH terms

  • Ecosystem
  • Mercury / analysis*
  • Models, Theoretical
  • North Carolina
  • Organomercury Compounds / analysis*
  • Rivers / chemistry*
  • Soil / chemistry
  • Soil Pollutants / analysis*
  • Urbanization
  • Water Pollutants, Chemical / analysis*
  • Wetlands*

Substances

  • Organomercury Compounds
  • Soil
  • Soil Pollutants
  • Water Pollutants, Chemical
  • Mercury