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Final Progress Reports: Dartmouth College: Methylmercury Production and Fate in Response to Multiple Environmental Factors

Superfund Research Program

Methylmercury Production and Fate in Response to Multiple Environmental Factors

Project Leader: Celia Y. Chen
Grant Number: P42ES007373
Funding Period: 2000-2021

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Final Progress Reports

Year:   2020  2013  2007  2004 

This project uses field studies, laboratory experiments, and modeling to investigate the effects of organic carbon, salinity, and temperature on methylmercury production and bioaccumulation in coastal ecosystems. Studies continued to demonstrate that these factors will impact coastal ecosystems’ response to climate change in the Northeast US and effectiveness of remediation at mercury contaminated sites. In a study of factors impacting mercury bioaccumulation in forage fish, the concentration of methylmercury, the more bioavailable and toxic species of mercury, is higher in water column particulates than in sediments, revealing the importance of this pelagic food pathway in transferring methylmercury to biota. Multifactor meta-analyses of mercury and ancillary field data have indicated that individual ecosystems have unique drivers of mercury dynamics resulting in strong separation of sites. However, there are consistent regional predictors of both water column mercury and forage fish mercury concentrations (Seelen 2020; Buckman 2020). Multiple variables including primary productivity, watershed land use, and organic carbon inputs are important in determining water column methylmercury levels, and water column concentrations drive bioaccumulation into forage fish. These meta-analyses also indicate that bulk sediments are not an important source of mercury to the water column or to biota except for highly contaminated ecosystems, which is a critical observation for understanding mercury cycling across ecosystems. The regional results also indicate that mercury cycling in contaminated sites are controlled by different sources, pathways, and processes from those in uncontaminated sites and these findings should inform future remediation strategies.

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