Watershed characteristics and chemical properties govern methyl mercury concentrations within headwater streams of boreal forests in Ontario, Canada.

Autor: Harrow-Lyle TJ; Department of Chemistry and Biology, Toronto Metropolitan University, 43 Gerrard St, Toronto, Ontario, M5B 2K, Canada. Electronic address: harrowlyle.tyler@gmail.com., Lam WY; University of Toronto Scarborough, 1265 Military Trail, Toronto, Ontario, M1C 1A4, Canada. Electronic address: wy.lam@mail.utoronto.ca., Emilson EJS; Natural Resources Canada, Canadian Forest Service, 1219 Queen Street E., Sault Ste. Marie, Ontario, P6A 2E5, Canada. Electronic address: erik.emilson@nrcan-rncan.gc.ca., Mackereth RW; Ministry Natural Resources and Forestry, 421 James St., Thunder Bay, Ontario, P7E 2V6, Canada. Electronic address: rob.mackereth@ontario.ca., Mitchell CPJ; University of Toronto Scarborough, 1265 Military Trail, Toronto, Ontario, M1C 1A4, Canada. Electronic address: carl.mitchell@utoronto.ca., Melles SJ; Department of Chemistry and Biology, Toronto Metropolitan University, 43 Gerrard St, Toronto, Ontario, M5B 2K, Canada. Electronic address: stephanie.melles@torontomu.ca.
Jazyk: angličtina
Zdroj: Journal of environmental management [J Environ Manage] 2023 Nov 01; Vol. 345, pp. 118526. Date of Electronic Publication: 2023 Jul 05.
DOI: 10.1016/j.jenvman.2023.118526
Abstrakt: Methyl mercury (MeHg) concentrations in boreal headwater streams are influenced by complex natural processes and disturbances such as forestry management. Understanding drivers of MeHg within boreal streams in Ontario, Canada, is of particular interest as there are legacy MeHg concerns. However, models accounting for the complexity of underlying processes have not yet been developed. We assessed how catchment characteristics and stream water chemistry influence MeHg concentrations within 19 watersheds of the Dryden - Wabigoon Forest in Ontario, Canada, using a structural equation modelling (SEM) approach. Despite the study area encompassing a large variation of boreal forest watersheds in the Canadian Shield, our SEM had substantial explanatory power across the region (χ 2 51  = 45.37, p-value = 0.70, R 2  = 0.75). Nitrate concentrations (p-value <0.001), water temperature (p-value = 0.002), and the latent watershed characteristic (p-value <0.001) had a positive influence on MeHg concentrations once variable interactions were accounted. Due to the inherent strengths of applying an SEM approach, we describe two plausible pathways driving MeHg concentrations: 1) indirect effect of forest-derived nutrients increases in-situ MeHg production in Dryden - Wabigoon Forest streams, and 2) direct supply of MeHg from inundated soils following consistent precipitation and inundation events (i.e., fill, sit, and spill).
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.
(Crown Copyright © 2023. Published by Elsevier Ltd. All rights reserved.)
Databáze: MEDLINE
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