Assessing the utility of sulfur isotope values for understanding mercury concentrations in water and biota from high Arctic lakes

Arctic Science

Karen A. Kidd¹  Meredith G. Clayden²  Gretchen L. Lescord²  Nelson J. O’Driscoll³  Jane L. Kirk⁴  Derek C.G. Muir⁴  Xiaowa Wang⁴ 

[1] Department of Biology, Canadian Rivers Institute, University of New Brunswick, 100 Tucker Park Road, Saint John, NB E2L 4L5, Canada. Department of Biology, School of Geography and Earth Sciences, McMaster University, 1280 Main Street West, Hamilton, ON L8S 4K1, Canada.;Department of Biology, Canadian Rivers Institute, University of New Brunswick, 100 Tucker Park Road, Saint John, NB E2L 4L5, Canada.;Department of Earth and Environmental Science, Acadia University, 32 University Avenue, Wolfville, NS B4P 2R6, Canada.;Environment and Climate Change Canada, Aquatic Contaminants Research Division, 867 Lakeshore Road, Burlington, ON L7S 1A1, Canada.;

关键词: sulfate;    food webs;    methylmercury;    oligotrophic;    bioaccumulation;   

DOI  :  10.1139/as-2018-0022

来源: DOAJ

【 摘 要 】

Methylmercury (MeHg) biomagnifies through aquatic food webs resulting in elevated concentrations in fish globally. Stable carbon and nitrogen isotopes are frequently used to determine dietary sources of MeHg and to model its biomagnification. However, given the strong links between MeHg and sulfur cycling, we investigated whether sulfur isotopes (δ34S) would improve our understanding of MeHg concentrations ([MeHg]) in Arctic lacustrine food webs. Delta34S values and total mercury (THg) or MeHg were measured in water, sediments, and biota from six lakes near Resolute Bay, NU, Canada. In two lakes impacted by historical eutrophication, aqueous sulfate δ34S was ∼8‰ more positive than sedimentary δ34S, suggestive of bacterial sulfate reduction in the sediment. In addition, aqueous δ34S showed a significant positive relationship with aqueous [MeHg] across lakes. Within taxa across lakes, [THg] in Arctic char muscle and [MeHg] in their main prey, chironomids, were positively related to their δ34S values across lakes, but inconsistent relationships were found across entire food webs among lakes. Across lakes, nitrogen isotopes were better predictors of biotic [THg] and [MeHg] than δ34S within this dataset. Our results suggest some linkages between Hg and S biogeochemistry in high Arctic lakes, which is an important consideration given anticipated climate-mediated changes in nutrient cycling.

【 授权许可】

Unknown