Issue 4, 2018

Response of mercury in an Adirondack (NY, USA) forest stream to watershed lime application

Abstract

Surface waters in Europe and North America previously impacted by acid deposition are recovering in conjunction with declining precursor emissions since the 1980s. Lime has been applied to some impacted watersheds to accelerate recovery. The response to liming can be considered a proxy for future recovery from acid deposition. Increases in dissolved organic carbon concentrations have been observed in surface waters in response to increased pH associated with recovery from acid deposition. Although not previously described, recovery-related increases in dissolved organic carbon could drive increases in mercury concentrations and loads because of the affinity of mercury for dissolved organic matter. We used a before–after impact-response approach to describe the response of stream mercury cycling to the application of lime to the watershed of a small stream in the Adirondack Mountains of New York, USA. Dissolved organic carbon, total mercury and methylmercury concentrations increased significantly in streamwater within two weeks of treatment, to previously unobserved concentrations. After six months, post-treatment before–after impact-control (BACI) tests indicate that mean dissolved organic carbon concentrations and total mercury to dissolved organic carbon ratios remained significantly higher and limed site fluxes of methylmercury were lower than those at the reference stream. This pattern suggests total mercury is leaching at elevated levels from the limed watershed, but limitations in production and transport to the stream channel likely resulted in increases in methylmercury concentration that were of limited duration.

Graphical abstract: Response of mercury in an Adirondack (NY, USA) forest stream to watershed lime application

Supplementary files

Article information

Article type
Paper
Submitted
30 Oct 2017
Accepted
17 Jan 2018
First published
24 Jan 2018

Environ. Sci.: Processes Impacts, 2018,20, 607-620

Response of mercury in an Adirondack (NY, USA) forest stream to watershed lime application

G. D. Millard, C. T. Driscoll, D. A. Burns, M. R. Montesdeoca and K. Riva-Murray, Environ. Sci.: Processes Impacts, 2018, 20, 607 DOI: 10.1039/C7EM00520B

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