Effects of mercury, organic carbon, and microbial inhibition on methylmercury cycling at the profundal sediment-water interface of a sulfate-rich hypereutrophic reservoir.

Autor: Fuhrmann BC; University of California, Environmental Systems Graduate Program, 5200 North Lake Road, Merced, CA, 95340, USA. Electronic address: byranf@sepro.com., Beutel MW; University of California, Environmental Systems Graduate Program, 5200 North Lake Road, Merced, CA, 95340, USA., O'Day PA; University of California, Environmental Systems Graduate Program, 5200 North Lake Road, Merced, CA, 95340, USA., Tran C; Environmental Analytical Laboratory, University of California, 5200 North Lake Rd, Merced, CA, 95340, USA., Funk A; City of San Diego, Public Utilities Department, 9192 Topaz Way, San Diego, CA, 92123, USA., Brower S; City of San Diego, Public Utilities Department, 9192 Topaz Way, San Diego, CA, 92123, USA., Pasek J; City of San Diego, Public Utilities Department, 9192 Topaz Way, San Diego, CA, 92123, USA., Seelos M; University of California, Environmental Systems Graduate Program, 5200 North Lake Road, Merced, CA, 95340, USA.
Jazyk: angličtina
Zdroj: Environmental pollution (Barking, Essex : 1987) [Environ Pollut] 2021 Jan 01; Vol. 268 (Pt B), pp. 115853. Date of Electronic Publication: 2020 Oct 15.
DOI: 10.1016/j.envpol.2020.115853
Abstrakt: Methylmercury (MeHg) produced by anaerobic bacteria in lakes and reservoirs, poses a threat to ecosystem and human health due to its ability to bioaccumulate in aquatic food webs. This study used 48-hr microcosm incubations of profundal sediment and bottom water from a sulfate-rich, hypereutrophic reservoir to assess seasonal patterns of MeHg cycling under various treatments. Treatments included addition of air, Hg(II), organic carbon, and microbial inhibitors. Both aeration and sodium molybdate, a sulfate-reducing bacteria (SRB) inhibitor, generally decreased MeHg concentration in microcosm water, likely by inhibiting SRB activity. The methanogenic inhibitor bromoethanesulfonate increased MeHg concentration 2- to 4- fold, suggesting that methanogens were potent demethylators. Pyruvate increased MeHg concentration under moderately reduced conditions, likely by stimulating SRB, but decreased it under highly reduced conditions, likely by stimulating methanogens. Acetate increased MeHg concentration, likely due to the stimulation of acetotrophic SRB. Results suggest that iron-reducing bacteria (IRB) were not especially prominent methylators and MeHg production at the sediment-water interface is elevated under moderately reduced conditions corresponding with SRB activity. In contrast, it is suppressed under oxic conditions due to low SRB activity, and under highly reduced conditions (<-100 mV) due to enhanced demethylation by methanogens.
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
(Copyright © 2020 Elsevier Ltd. All rights reserved.)
Databáze: MEDLINE
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