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

Arctic Science

article

Gretchen L. Lescord¹  Meredith G. Clayden¹  Karen A. Kidd¹  Jane L. Kirk⁴  Xiaowa Wang⁴  Nelson J. O’Driscoll⁵  Derek C.G. Muir⁴ 

[1] Department of Biology, Canadian Rivers Institute, University of New Brunswick;Freshwater Cooperative Unit, Vale Living with Lakes Centre, Laurentian University;Department of Biology, School of Geography and Earth Sciences, McMaster University;Aquatic Contaminants Research Division;Department of Earth and Environmental Science, Acadia University, 32 University Avenue

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

DOI  :  10.1139/as-2018-0022

学科分类：地球科学(综合)

来源: NRC Research Press

【 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 (δ 34 S) would improve our understanding of MeHg concentrations ([MeHg]) in Arctic lacustrine food webs. Delta 34 S 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 δ 34 S was ∼8‰ more positive than sedimentary δ 34 S, suggestive of bacterial sulfate reduction in the sediment. In addition, aqueous δ 34 S 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 δ 34 S 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 δ 34 S 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】

CC BY