The impact of over 100 years of wildfires on mercury levels and accumulation rates in two lakes in southern California, USA

Rothenberg, Sarah E.; Kirby, Matthew E.; Bird, Broxton W.; DeRose, Margie; Lin, Cheng-Ju; Feng, Xinbin; Ambrose, Richard F.; Jay, Jennifer A.

doi:10.1007/s12665-009-0238-7

Cited by 18 publications

(21 citation statements)

References 55 publications

(62 reference statements)

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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

258

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

Schuster

Schaefer

Aiken

et al. 2018

Geophysical Research Letters

258

196

View full text Add to dashboard Cite

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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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“…In 2009 solid‐phase THg samples were analyzed with a portable Hg vapor analyzer (Lumex, Model RA‐915+/PYRO‐915+, St. Petersburg, Russia), using methods described in U.S. EPA Method 7473 [ EPA , 2007] involving thermal decomposition, amalgamation and atomic absorption spectrophotometry, and no pre‐digestion steps were required. The two methods (1631[ EPA , 2002] and 7473 [ EPA , 2007]) were previously compared, and the correlation (r) was 0.78 for 17 samples [ Rothenberg et al , 2010]. In 2008 and 2009 sediment MeHg concentrations were analyzed following solvent extraction with dichloromethane (CH 2 Cl 2 ) to minimize matrix interferences [ Liang et al , 2004].…”

Section: Methodsmentioning

confidence: 99%

Mercury cycling in a flooded rice paddy

Rothenberg

Feng

2012

J. Geophys. Res.

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[1] 2009, mercury (Hg) cycling was investigated in a flooded rice paddy in the Wanshan Hg mining region of eastern Guizhou, China, in the rice-planted (2008 and 2009) and fallow (2009) sections of the same paddy. In the rice-planted section, pore water was more acidic and pore water methylmercury (MeHg) concentrations were higher compared to the fallow section. However, iron (Fe) and sulfur (S) cycling differed in 2008 and 2009, with higher sediment Fe concentrations in 2009, when pore water MeHg and sulfate concentrations were more strongly correlated in the rice-planted section. We explored whether elevated sediment Fe contributed to S cycling and hence, Hg(II)-methylation. Critical pH values for formation of FeS (s) were estimated. Based on pore water pH collected in both sections of the paddy, the fallow section was more often a sink for FeS (s) , while FeS (s) did not form in the rice-planted section, although sulfide concentrations were low in both sections in both years (i.e.,<10 mM). We hypothesized Fe(III) oxidized sulfide, and intermediate S species (e.g., polysulfides) were further oxidized to sulfate instead of forming FeS (s) , thus prolonging sulfate reduction and promoting Hg(II)-methylation in the rice-planted section in 2009. Results suggested Fe(III) reduction increased electron acceptors for sulfate-reducing bacteria, which indirectly enhanced Hg(II)-methylation. Additionally, highest sediment MeHg concentrations were observed in the fallow section after the paddy was dried and re-wetted, indicating water-saving rice cultivation practices (e.g., alternating wetting and drying), may cause MeHg concentrations in paddy soil to spike, which should be further investigated.

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The impact of over 100 years of wildfires on mercury levels and accumulation rates in two lakes in southern California, USA

Cited by 18 publications

References 55 publications

Permafrost Stores a Globally Significant Amount of Mercury

Permafrost Stores a Globally Significant Amount of Mercury

Permafrost Stores a Globally Significant Amount of Mercury

Mercury cycling in a flooded rice paddy

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