Superfund Research Program
Methylmercury Production and Fate in Response to Multiple Environmental Factors
Project Leader: Celia Y. Chen
Grant Number: P42ES007373
Funding Period: 2000-2020
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 and effectiveness of remediation at mercury contaminated sites. Sediment organic carbon amounts are negatively related to concentrations in biota with significant interactions between both sediment organic carbon and temperature driving patterns of bioaccumulation (Curtis et al., 2019; Buckman et al., 2019). Salinity effects on mercury concentration of primary consumers are variable (Curtis et al., 2019) but have a more pronounced effect on uptake into phytoplankton, with lower salinities linked to higher particulate mercury concentrations, along with lower sediment organic carbon, and higher temperature (Curtis et al., in prep). 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 et al., in prep; Buckman et al., in prep). Multiple variables including primary productivity, watershed land use, and organic carbon inputs are important in determining water column methylmercury (MeHg) 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.