Deforestation and cultivation mobilize mercury from topsoil

Gamby, Rebecca L.; Hammerschmidt, Chad R.; Costello, David M.; Lamborg, Carl H.; Runkle, James R.

doi:10.1016/j.scitotenv.2015.06.025

Cited by 21 publications

(15 citation statements)

References 57 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The soil THg concentrations in our study area are on the lower end of concentrations measured in Scandinavia (0.15 to 0.37 μg g −1 ) where other studies examining the effects of forestry operations on Hg mobilization have been conducted. [45][46][47] Soil THg concentrations were positively correlated with soil organic matter (R 2 = 0.35, p < 0.001; Figure S3 in the SI), thus the relatively high soil Hg concentrations in our study area (as well as those from the other Hg forestry studies in Scandinavia) are likely related to the high organic matter content (mean %LOI: 35 ± 1.9%) of the soils effectively sequestering atmospherically deposited Hg. 12,23 The similarity in soil Hg contents between forested and harvested catchments likely exists because measurements were obtained within the first few months to a year following harvest.…”

Section: Mercury Concentrations In Precipitation Soil and Sedimentmentioning

confidence: 62%

Stream Mercury Export in Response to Contemporary Timber Harvesting Methods (Pacific Coastal Mountains, Oregon, USA)

Eckley

Eagles‐Smith

Tate

et al. 2018

Environ. Sci. Technol.

View full text Add to dashboard Cite

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 were measured monthly for 1.5 years following logging in three paired harvested and unharvested (control) catchments. There was no significant difference in particulate-bound Hg concentrations or loads in the harvested and unharvested catchments which may have resulted from forestry 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) in harvested, unharvested, 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 that support methylation. These results have important implications for the role forestry operations have in affecting catchment retention and export of Hg pollution.

show abstract

Section: Mercury Concentrations In Precipitation Soil and Sedimentmentioning

confidence: 62%

Stream Mercury Export in Response to Contemporary Timber Harvesting Methods (Pacific Coastal Mountains, Oregon, USA)

Eckley

Eagles‐Smith

Tate

et al. 2018

Environ. Sci. Technol.

View full text Add to dashboard Cite

show abstract

“…In addition, deposition of gaseous Hg to vegetation can have a large impact on the net amount of Hg released from a landscape, and the reduction in plant uptake following forestry operations increases the net evasion of Hg to the atmosphere (Eckley et al 2016 ). Releases of Hg from the surface following forest harvesting may be similar or larger in magnitude to losses via aqueous fluxes (Mazur et al 2014 ; Gamby et al 2015 ; Eckley et al 2016 ). Despite increased releases to air and water, harvested catchments are still expected to be a net-sink for atmospheric Hg inputs, albeit less efficient ones compared to undisturbed forests (Fig.…”

Section: Forestry and Deforestationmentioning

confidence: 99%

Challenges and opportunities for managing aquatic mercury pollution in altered landscapes

Hsu‐Kim

Eckley

Achá

et al. 2018

Ambio

205

123

View full text Add to dashboard Cite

The environmental cycling of mercury (Hg) can be affected by natural and anthropogenic perturbations. Of particular concern is how these disruptions increase mobilization of Hg from sites and alter the formation of monomethylmercury (MeHg), a bioaccumulative form of Hg for humans and wildlife. The scientific community has made significant advances in recent years in understanding the processes contributing to the risk of MeHg in the environment. The objective of this paper is to synthesize the scientific understanding of how Hg cycling in the aquatic environment is influenced by landscape perturbations at the local scale, perturbations that include watershed loadings, deforestation, reservoir and wetland creation, rice production, urbanization, mining and industrial point source pollution, and remediation. We focus on the major challenges associated with each type of alteration, as well as management opportunities that could lessen both MeHg levels in biota and exposure to humans. For example, our understanding of approximate response times to changes in Hg inputs from various sources or landscape alterations could lead to policies that prioritize the avoidance of certain activities in the most vulnerable systems and sequestration of Hg in deep soil and sediment pools. The remediation of Hg pollution from historical mining and other industries is shifting towards in situ technologies that could be less disruptive and less costly than conventional approaches. Contemporary artisanal gold mining has well-documented impacts with respect to Hg; however, significant social and political challenges remain in implementing effective policies to minimize Hg use. Much remains to be learned as we strive towards the meaningful application of our understanding for stakeholders, including communities living near Hg-polluted sites, environmental policy makers, and scientists and engineers tasked with developing watershed management solutions. Site-specific assessments of MeHg exposure risk will require new methods to predict the impacts of anthropogenic perturbations and an understanding of the complexity of Hg cycling at the local scale.Electronic supplementary materialThe online version of this article (10.1007/s13280-017-1006-7) contains supplementary material, which is available to authorized users.

show abstract

“…Dried sediment (0.5–1.0 g) was accurately weighed into 60‐mL digestion vials, to which was added 10 mL of 16 M HNO 3 and 0.5 mL of BrCl solution , and then digested for 6 h in a hot block at 95 °C. Digestates were diluted with reagent‐grade water (nominal resistivity >18 MΩ‐cm), and total Hg was determined by either inductively coupled plasma mass spectrometry (ICP‐MS) with a Perkin Elmer ELAN 9000 or, for reference sediments, by dual‐Au amalgamation cold vapor atomic fluorescence spectrometry (AFS) . Methylmercury was extracted from separate aliquots of dried sediment (0.25–0.50 g) by aqueous distillation and quantified by gas‐chromatographic cold vapor AFS after derivatization with sodium tetraethylborate .…”

Section: Methodsmentioning

confidence: 99%

Net methylmercury production in 2 contrasting stream sediments and associated accumulation and toxicity to periphyton

Klaus

Hammerschmidt

Costello

et al. 2016

Enviro Toxic and Chemistry

Self Cite

View full text Add to dashboard Cite

Periphyton uptake of bioaccumulative methylmercury (MeHg) may be an important entryway into the food web of many stream ecosystems where periphyton can be dominant primary producers. The net production of MeHg in stream sediment, its bioaccumulation in periphyton, and the potential toxicity of divalent Hg (Hg[II]) and MeHg in sediment to periphyton were investigated with a 67-d in situ incubation experiment using chemical exposure substrates containing either a fine-grained, organic-rich or a sandy, low-organic sediment, each amended with varying concentrations of mercuric chloride. Methylmercury was produced in sediment, and concentrations increased with greater amounts of added Hg(II); however, the net production of MeHg was inhibited in the highest Hg(II) treatments of both sediments. The range of total Hg concentrations that inhibited MeHg production was between approximately 80 000 ng Hg and 350 000 ng Hg per gram of organic matter for both sediments. Periphyton colonizing substrates accumulated MeHg in proportion to the concentration in sediment, but periphyton exposed to the sandy sediment accumulated approximately 20-fold more than those exposed to the organic-rich sediment relative to sediment MeHg concentrations. Toxicity of either Hg(II) or MeHg to periphyton was not observed with either periphyton organic content, net primary production, or respiration as endpoints. These results suggest that in situ production and bioaccumulation of MeHg in stream ecosystems can vary as a function of sediment characteristics and Hg(II) loadings to the sediment. Environ Toxicol Chem 2016;35:1759-1765. © 2015 SETAC.

show abstract

Deforestation and cultivation mobilize mercury from topsoil

Cited by 21 publications

References 57 publications

Stream Mercury Export in Response to Contemporary Timber Harvesting Methods (Pacific Coastal Mountains, Oregon, USA)

Stream Mercury Export in Response to Contemporary Timber Harvesting Methods (Pacific Coastal Mountains, Oregon, USA)

Challenges and opportunities for managing aquatic mercury pollution in altered landscapes

Net methylmercury production in 2 contrasting stream sediments and associated accumulation and toxicity to periphyton

Contact Info

Product

Resources

About