Mercury concentrations and export from small central Canadian boreal forest catchments before, during, and after forest harvest.

Autor: Lam WY; Department of Physical and Environmental Sciences, University of Toronto Scarborough, Toronto, ON, Canada., Mackereth RW; Centre for Northern Forest Ecosystem Research, Ontario Ministry of Natural Resources and Forestry, Thunder Bay, ON, Canada., Mitchell CPJ; Department of Physical and Environmental Sciences, University of Toronto Scarborough, Toronto, ON, Canada. Electronic address: carl.mitchell@utoronto.ca.
Jazyk: angličtina
Zdroj: The Science of the total environment [Sci Total Environ] 2024 Feb 20; Vol. 912, pp. 168691. Date of Electronic Publication: 2023 Nov 22.
DOI: 10.1016/j.scitotenv.2023.168691
Abstrakt: Northern boreal forests are a strong sink for mercury (Hg), a global contaminant of significant concern to wildlife and human health. Mercury stored in forest soils can be mobilized via runoff and erosion, and under suitable conditions can be methylated to its much more bioaccumulative form, methylmercury. Forest harvesting can affect the mobilization and methylation of Hg, though the direction and magnitude of the impact is unclear or conflicting across previous studies. This study examined 5 harvested and 2 reference watersheds in northwestern Ontario, Canada, before, during, and after harvest to quantify changes in stream total and methylmercury concentration and loads and identified potential landscape and management factors that contribute to differences in stream response. In watersheds where streams were buffered by natural vegetation (≥30 m), no significant changes in total Hg or methylmercury concentrations or loads were observed. Significant increases in methylmercury concentrations and loads were observed downstream of a stream crossing in a watershed where the relatively small stream was unmapped and therefore only buffered by a 3 m machine exclusion zone. These results show that when current best management practices that minimize soil and water disturbance are followed, harvest can have a minimal impact on total and methylmercury loads, even in extensively harvested watersheds. However, there is a need for improved mapping of small streams to ensure best management practices are applied adequately across the landscape.
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.
(Copyright © 2023 Elsevier B.V. All rights reserved.)
Databáze: MEDLINE
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