Stream mercury export in response to contemporary timber harvesting methods (Pacific Coastal Mountains, Oregon, USA)

Environmental Science & Technology
By: , and 

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Abstract

Land-use activities can alter hydrological and biogeochemical processes that can affect the fate, transformation, and transport of mercury (Hg). Previous studies in boreal forests have shown that forestry operations can have profound, but variable effects on Hg export and methylmercury (MeHg) formation. The Pacific Northwest is an important timber producing region that receives large atmospheric Hg loads, but the impact of forest harvesting on Hg mobilization has not been directly studied and was the focus of our investigation. Stream discharge was measured continuously and Hg and MeHg concentrations measured monthly for 1.5 years following logging in three paired harvested and un-harvested catchments. There was no significant difference in particulate-bound Hg concentrations or loads in the harvested and unharvested catchments which may have resulted from the best management practices aimed at minimizing erosion. However, the harvested catchments had significantly higher discharge (32%), filtered Hg concentrations (28%), filtered Hg loads (80%), and dissolved organic carbon (DOC) loads (40%) compared to forested catchments. MeHg concentrations were low (mostly <0.05 ng L-1) in both harvested, un-harvested and downstream samples due to well-drained/unsaturated soil conditions and steep slopes with high energy eroding stream channels that were not conducive to the development of anoxic conditions. These results have important implications for the role forestry operations have in affecting catchment retention and export of Hg pollution.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Stream mercury export in response to contemporary timber harvesting methods (Pacific Coastal Mountains, Oregon, USA)
Series title Environmental Science & Technology
DOI 10.1021/acs.est.7b05197
Volume 52
Issue 4
Year Published 2019
Language English
Publisher ACS Publications
Contributing office(s) Wisconsin Water Science Center, WMA - Laboratory & Analytical Services Division, Upper Midwest Water Science Center, Oregon Water Science Center, National Research Program - Central Branch, Forest and Rangeland Ecosystem Science Center
Description 10 p.
First page 1971
Last page 1980
Country United States
State Oregon
Other Geospatial Trask River