In August 2017, Hurricane Harvey caused catastrophic flooding in southeastern Texas and dispersed liquid elemental mercury [Hg(0)] from an unknown source to an area east of Houston. Preliminary measurements performed days after the hurricane showed mercury concentrations exceeding 2500 mg/kg in floodplain sediments of the San Jacinto River. Because mercury is a highly toxic element, the hurricane-induced contamination may pose a significant threat to public health. This project aims to elucidate the geochemical controls on the methylation of elemental mercury [Hg(0)] in San Jacinto River sediments. Floodplain and river sediment samples will be collected and analyzed for mercury methylation activity. NSF funds will be used to train graduate and undergraduate students at Rutgers University to carry out field work and laboratory mercury analyses. An examination of the transformations of elemental mercury in San Jacinto River sediments dispersed by Hurricane Harvey is a unique opportunity to investigate the fate of elemental mercury in sediments shortly after release and will provide critical information for the development of accurate contaminant transport models and future remediation efforts.Recent laboratory experiments have shown that certain anaerobic bacteria can take up dissolved Hg(0) and transform intracellular Hg to methylmercury. However, the occurrence of this microbial process in contaminated sediments has not been investigated, and anaerobic methylation of liquid Hg(0) by microbial communities remains poorly understood. In this project, floodplain and river sediment samples collected along the San Jacinto River will be used to test two hypotheses: 1) Elemental mercury in contaminated sediments is converted to methylmercury under anoxic, water-saturated condition; under oxic conditions, elemental mercury is oxidized, but not methylated; and 2) Elevated mercury concentrations in sediments inhibits mercury methylation due to toxicity effects on the microbial community. Laboratory experiments carried out by the research team and students at Rutgers University will test these hypotheses with the goal of obtaining new insights into the geochemical controls on Hg(0) oxidation and methylation in contaminated sediments. NSF funds will be used to train 2 Ph.D. students and 2 undergraduate students. The students will gain interdisciplinary experiences in geochemistry and microbiology as state-of?the-art disciplines in environmental geosciences. The results of this project will be disseminated through peer-reviewed publications and presentations at national conferences. By elucidating the geochemical conditions that promote methylmercury production, the investigators aim to better inform local public health officials and environmental managers about the possible dangers associated with this contamination event.
|Effective start/end date||10/1/17 → 9/30/18|
- National Science Foundation (National Science Foundation (NSF))