Canadian Forest Service Publications

Optical Properties of Dissolved Organic Matter and Their Relation to Mercury Concentrations in Water and Biota Across a Remote Freshwater Drainage Basin. 2018. Lescord, G.L.; Emilson, E.J.S.; Johnston, T.A.; Branfireun, B.A.; Gunn, J.M. Environmental Science & Technology: http://10.1021/acs.est.7b05348.

Year: 2018

Issued by: Great Lakes Forestry Centre

Catalog ID: 39070

Language: English

Availability: PDF (request by e-mail)

Available from the Journal's Web site.
DOI: 10.1021/acs.est.7b05348

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Plain Language Summary

Dissolved organic matter (DOM) includes an array of carbon-based compounds that vary in size and structure and have complex interactions with mercury (Hg) cycling in aquatic systems. While many studies have examined the relationship between dissolved organic carbon concentrations ([DOC]) and methyl Hg bioaccumulation, few studies have considered the effects of DOM composition (e.g., protein-content, aromaticity). The goal of this study was to explore the relationships between total and methyl [Hg] in water, invertebrates, and fish, and optically-derived measures of DOM composition from 47 lake and river sites across a boreal watershed. Results showed higher aqueous total [Hg] in systems with more terrestrial DOM and higher [DOC], potentially due to enhanced transport from upstream or riparian forest areas. Methyl [Hg] in biota were all positively related to the amount of microbial-based DOM and, in some cases, to the proportions of labile and protein-like DOM. These results suggest that increased Hg bioaccumulation is related to the availability of labile DOM, potentially due to enhanced methylation. DOM composition explained 68% and 54% more variability in [Hg] in surface waters and large-bodied fish, respectively, than [DOC] alone. These results show that optical measures of DOM characteristics are a valuable tool for understanding DOM-Hg biogeochemistry in forested watersheds.