Forest Structure Affects Soil Mercury Losses in the Presence and Absence of Wildfire

Homann, Peter S.; Darbyshire, Robyn L.; Bormann, Bernard T.; Morrissette, Brett A.

doi:10.1021/acs.est.5b03355

Cited by 18 publications

(13 citation statements)

References 70 publications

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“…Also within the range of our Hg emissions, Engle et al (2006) found emissions of 2.6 and 3.6 g ha À1 for Hg for wildfire and prescribed fire for forest fires in the Sierra Nevada. Homann et al (2015) found generally higher Hg emissions for forest wildfires in south-western Oregon in unthinned, thinned and clearcut sites (,4.5, 18 and 20 g ha À1 ). Hg emissions from the unthinned site were from the forest floor only and were comparable to emissions for our highest soil fire severity burn class (4.6 g ha À1 ), while both thinned and clearcut sites also had losses from upper mineral soils (A horizon) leading to higher Hg emissions.…”

Section: Discussionmentioning

confidence: 86%

Emissions of forest floor and mineral soil carbon, nitrogen and mercury pools and relationships with fire severity for the Pagami Creek Fire in the Boreal Forest of northern Minnesota

Kolka

Sturtevant

Miesel

et al. 2017

Int. J. Wildland Fire

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Forest fires cause large emissions of C (carbon), N (nitrogen) and Hg (mercury) to the atmosphere and thus have important implications for global warming (e.g. via CO 2 and N 2 O emissions), anthropogenic fertilisation of natural ecosystems (e.g. via N deposition), and bioaccumulation of harmful metals in aquatic and terrestrial systems (e.g. via Hg deposition). Research indicates that fires are becoming more severe over much of North America, thus increasing element emissions during fire. However, there has been little research relating forest floor and mineral soil losses of C, N and Hg to on-the-ground indices of fire severity that enable scaling up those losses for larger-scale accounting of fire-level emissions. We investigated the relationships between forest floor and mineral soil elemental pools across a range of soil-level fire severities following the 2011 Pagami Creek wildfire in northern Minnesota, USA. We were able to statistically differentiate losses of forest floor C, N and Hg among a five-class soil-level fire severity classification system. Regression relationships using soil fire severity class were able to predict remaining forest floor C, N and Hg pools with 82-96% confidence. We correlated National Aeronautics and Space Administration Airborne Visible and Infrared Imaging Spectrometer-Classic imagery to ground-based plot-scale estimates of soil fire severity to upscale emissions of C, N and Hg to the fire level. We estimate that 468 000 Mg C, 11 000 Mg of N and over 122 g of Hg were emitted from the forest floor during the burning of the 28 310 ha upland area of the Pagami Creek fire.Abstract. Forest fires cause large emissions of C (carbon), N (nitrogen) and Hg (mercury) to the atmosphere and thus have important implications for global warming (e.g. via CO 2 and N 2 O emissions), anthropogenic fertilisation of natural ecosystems (e.g. via N deposition), and bioaccumulation of harmful metals in aquatic and terrestrial systems (e.g. via Hg deposition). Research indicates that fires are becoming more severe over much of North America, thus increasing element emissions during fire. However, there has been little research relating forest floor and mineral soil losses of C, N and Hg to on-the-ground indices of fire severity that enable scaling up those losses for larger-scale accounting of fire-level emissions. We investigated the relationships between forest floor and mineral soil elemental pools across a range of soil-level fire severities following the 2011 Pagami Creek wildfire in northern Minnesota, USA. We were able to statistically differentiate losses of forest floor C, N and Hg among a five-class soil-level fire severity classification system. Regression relationships using soil fire severity class were able to predict remaining forest floor C, N and Hg pools with 82-96% confidence. We correlated National Aeronautics and Space Administration Airborne Visible and Infrared Imaging Spectrometer-Classic imagery to ground-based plot-scale estimates of soil fire severity to upscale emissions o...

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Section: Discussionmentioning

confidence: 86%

Emissions of forest floor and mineral soil carbon, nitrogen and mercury pools and relationships with fire severity for the Pagami Creek Fire in the Boreal Forest of northern Minnesota

Kolka

Sturtevant

Miesel

et al. 2017

Int. J. Wildland Fire

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“…Several atmospheric Hg sources unique to the northern high latitudes have significant spatial and temporal variability to explain STHg variability within and between cores (Fitzgerald & Lamborg, 2003). Northern boreal forest fires release Hg into the atmosphere leading to spatial variability in Hg deposition (Homann et al, 2015;Rothenberg et al, 2010;Turetsky, et al, 2006). Spatial variations in temperature and moisture change microbial respiration rates (Wickland et al, 2006).…”

Section: Discussionmentioning

confidence: 99%

Permafrost Stores a Globally Significant Amount of Mercury

Schuster

Schaefer

Aiken

et al. 2018

Geophysical Research Letters

270

196

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Changing climate in northern regions is causing permafrost to thaw with major implications for the global mercury (Hg) cycle. We estimated Hg in permafrost regions based on in situ measurements of sediment total mercury (STHg), soil organic carbon (SOC), and the Hg to carbon ratio (RHgC) combined with maps of soil carbon. We measured a median STHg of 43 ± 30 ng Hg g soil−1 and a median RHgC of 1.6 ± 0.9 μg Hg g C−1, consistent with published results of STHg for tundra soils and 11,000 measurements from 4,926 temperate, nonpermafrost sites in North America and Eurasia. We estimate that the Northern Hemisphere permafrost regions contain 1,656 ± 962 Gg Hg, of which 793 ± 461 Gg Hg is frozen in permafrost. Permafrost soils store nearly twice as much Hg as all other soils, the ocean, and the atmosphere combined, and this Hg is vulnerable to release as permafrost thaws over the next century. Existing estimates greatly underestimate Hg in permafrost soils, indicating a need to reevaluate the role of the Arctic regions in the global Hg cycle.

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Section: Discussionmentioning

confidence: 99%

Permafrost Stores a Globally Significant Amount of Mercury

Schaefer

Schuster

Antweiler

et al. 2021

World Scientific Encyclopedia of Climate Change

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Changing climate in northern regions is causing permafrost to thaw with major implications for the global mercury (Hg) cycle. We estimated Hg in permafrost regions based on in situ measurements of sediment total mercury (STHg), soil organic carbon (SOC), and the Hg to carbon ratio (R HgC ) combined with maps of soil carbon. We measured a median STHg of 43 ± 30 ng Hg g soil À1 and a median R HgC of 1.6 ± 0.9 μg Hg g C À1 , consistent with published results of STHg for tundra soils and 11,000 measurements from 4,926 temperate, nonpermafrost sites in North America and Eurasia. We estimate that the Northern Hemisphere permafrost regions contain 1,656 ± 962 Gg Hg, of which 793 ± 461 Gg Hg is frozen in permafrost. Permafrost soils store nearly twice as much Hg as all other soils, the ocean, and the atmosphere combined, and this Hg is vulnerable to release as permafrost thaws over the next century. Existing estimates greatly underestimate Hg in permafrost soils, indicating a need to reevaluate the role of the Arctic regions in the global Hg cycle.

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Forest Structure Affects Soil Mercury Losses in the Presence and Absence of Wildfire

Cited by 18 publications

References 70 publications

Emissions of forest floor and mineral soil carbon, nitrogen and mercury pools and relationships with fire severity for the Pagami Creek Fire in the Boreal Forest of northern Minnesota

Emissions of forest floor and mineral soil carbon, nitrogen and mercury pools and relationships with fire severity for the Pagami Creek Fire in the Boreal Forest of northern Minnesota

Permafrost Stores a Globally Significant Amount of Mercury

Permafrost Stores a Globally Significant Amount of Mercury

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