Impacts of forest harvesting on mercury concentrations and methylmercury production in boreal forest soils and stream sediment.

Autor: Huang H; 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: Environmental pollution (Barking, Essex : 1987) [Environ Pollut] 2024 Jan 15; Vol. 341, pp. 122966. Date of Electronic Publication: 2023 Nov 17.
DOI: 10.1016/j.envpol.2023.122966
Abstrakt: Methylmercury (MeHg) is the most neurotoxic and bioaccumulative form of mercury (Hg) present in the terrestrial and aquatic food sources of boreal ecosystems, posing potential risks to wildlife and human health. Harvesting impacts on Hg methylation and MeHg concentrations in forest soils and stream sediment are not fully understood. In this study, a field investigation was carried out in 4 harvested and 2 unharvested boreal forest watersheds, before and after harvest, to better understand impacts on Hg methylation and MeHg concentration in soils and stream sediment, including their responses to different forest management practices. Changes in total Hg (THg) and MeHg concentrations, first-order potential rate constants for Hg methylation and MeHg demethylation (K meth and K demeth ) as well as total carbon content and carbon-to-nitrogen ratio post-harvest in upland, wetland and riparian soils and stream sediment were assessed and compared. Increases in MeHg production were minimal in upland, wetland or riparian soils after harvest. Sediment in streams with minor buffer protection (∼3 m), greater fractions (>75%) of harvested watershed area and more road construction had significantly increased THg and MeHg concentrations, %-MeHg, K meth and total carbon content post-harvest. From these patterns, we infer that inputs of carbon and inorganic Hg into harvest-impacted stream sediment are likely sourced from the harvested upland areas and stimulate in situ MeHg production in stream sediment. These findings indicate the importance of stream sediment as potential MeHg pools in harvested forest watersheds. The findings also demonstrate that forest management practices aiming to mitigate organic matter and Hg inputs to streams can effectively alleviate harvesting impacts on Hg methylation and MeHg concentrations in stream sediment.
Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests:In-kind support, specifically access to field sites and timely information regarding harvest schedules, was provided by Domtar and Dryden Forest Management Company. Neither company was involved in data collection, data analysis or the writing of this manuscript.
(Copyright © 2023 Elsevier Ltd. All rights reserved.)
Databáze: MEDLINE
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