Effects of Nutrient Loading and Mercury Chemical Speciation on theFormation and Degradation of Methylmercury in Estuarine Sediment
2016 (English)In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 50, 6983-6990 p.Article in journal (Refereed) Published
Net formation of methylmercury (MeHg) insediments is known to be affected by the availability ofinorganic divalent mercury (HgII) and by the activities of HgIImethylating and MeHg demethylating bacteria. Enhancedautochthonous organic matter deposition to the benthic zone,following increased loading of nutrients to the pelagic zone, hasbeen suggested to increase the activity of HgIImethylatingbacteria and thus the rate of net methylation. However, theimpact of increased nutrient loading on the biogeochemistry ofmercury (Hg) is challenging to predict as different geochemicalpools of Hg may respond differently to enhanced bacterialactivities. Here, we investigate the combined effects of nutrient(N and P) supply to the pelagic zone and the chemicalspeciation of HgIIand of MeHg on MeHg formation and degradation in a brackish sediment-water mesocosm model ecosystem.By use of Hg isotope tracers addedin situto the mesocosms orex situin incubation experiments, we show that the MeHgformation rate increased with nutrient loading only for HgIItracers with a high availability for methylation. Tracers with lowavailability did not respond significantly to nutrient loading. Thus, both microbial activity (stimulated indirectly through planktonbiomass production by nutrient loading) and HgIIchemical speciation were found to control the MeHg formation rate in marinesediments.
Place, publisher, year, edition, pages
American Chemical Society (ACS), 2016. Vol. 50, 6983-6990 p.
IdentifiersURN: urn:nbn:se:umu:diva-125668DOI: 10.1021/acs.est.6b01567OAI: oai:DiVA.org:umu-125668DiVA: diva2:970579