Wildfires threaten mercury stocks in northern soils

Turetsky, M. R.; Harden, Jennifer W.; Friedli, H.; Flannigan, Mike D.; Payne, Nicholas J.; Crock, J.G.; Radke, Lawrence F.

doi:10.1029/2005gl025595

Cited by 118 publications

(109 citation statements)

References 37 publications

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“…, with one study reporting 1476 × 10 -6 g Hg (kg fuel burned) -1 (Turetsky et al, 2006). Removing the smallest and largest values of these seven, and taking the average of the remaining five studies, yields an average of 134 × 10 -6 g Hg (kg fuel burned) -1 , in agreement with the (140 ± 27) × 10 -6 g Hg (kg fuel burned) -1 found in 30 our work.…”

Section: Optimized Emission Factorssupporting

confidence: 84%

How important is biomass burning in Canada to mercury contamination?

Fraser¹,

Dastoor²,

Ryjkov³

2017

Preprint

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Abstract.Wildfire frequency has increased in past four decades in Canada, and is expected to increase in future as a result of climate change (Wotton et. al. 2010). Mercury (Hg) emissions from biomass burning are known to be significant; however, the impact of biomass burning on air concentration and deposition fluxes in Canada has not been previously quantified. We use 10 estimates of burned biomass from FINN (Fire Inventory from NCAR) and vegetation-specific Emission Factors (EFs) of mercury to investigate the spatiotemporal variability of Hg emissions in Canada. We use Environment and Climate Change Canada's GEM-MACH-Hg (Global Environmental Multi-scale, Modelling Air quality and Chemistry model, mercury version) to quantify the impact of biomass burning in Canada on spatiotemporal variability of air concentrations and deposition fluxes of mercury in Canada. We use North American gaseous elemental mercury (GEM) observations (2010)(2011)(2012)(2013)(2014)(2015), 15 and an inversion technique to optimize the emission factors for GEM for five vegetation types represented in North American fires to constrain the biomass burning impacts of mercury. We use three biomass burning Hg emissions scenarios in Canada to conduct three sets of model simulations for 2010-2015: two scenarios where Hg is emitted only as GEM using literature or optimized EFs, and a third scenario where Hg is emitted as GEM using literature EFs and particle bound mercury (PBM) emitted using the average GEM/PBM ratio from lab measurements. The three biomass burning emission scenarios represent the range of 20 possible values for the impacts of Hg emissions from biomass burning in Canada on Hg concentration and deposition.We find total biomass burning Hg emissions to be highly variable from year to year, and estimate average 2010-2015 total atmospheric biomass burning emissions of Hg in Canada to be between 6-14 t during the biomass burning season (i.e., from May to September), which is 3 -7 times the mercury emission from anthropogenic sources in Canada for this period. On average, 65% of the emissions occur in the provinces west of Ontario. We find that while emissions from biomass burning have a small 25 impact on surface air concentrations of GEM averaged over individual provinces/territories, the impact at individual sites can be as high as 95% during burning events. We estimate average annual mercury deposition from biomass burning in Canada to be between 0.3 -2.8 t, compared to 0.14 t of mercury deposition from anthropogenic sources during the biomass burning season in Canada. Compared to the biomass burning emissions, the relative impact of fires on mercury deposition is shifted eastward, with on average 54% percent of the deposition occurring in provinces west of Ontario. While the relative contribution of Canadian 30 biomass burning to the total mercury deposition over each province/territory is no more than 9% between 2010-2015, the local contribution in some locations (including areas downwind of biomass burning) can be as high as...

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Section: Optimized Emission Factorssupporting

confidence: 84%

How important is biomass burning in Canada to mercury contamination?

Fraser¹,

Dastoor²,

Ryjkov³

2017

Preprint

View full text Add to dashboard Cite

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“…It is not known whether organic-bound mercury is emitted or retained in the soil when the carbon is respired. Boreal peatland fires may have very high mercury emissions from burning of the peat (Turetsky et al, 2006).…”

Section: Effect Of Climate Change On Mercurymentioning

confidence: 99%

Effect of climate change on air quality

Jacob

Winner

2009

Atmospheric Environment

1,545

1,232

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a b s t r a c tAir quality is strongly dependent on weather and is therefore sensitive to climate change. Recent studies have provided estimates of this climate effect through correlations of air quality with meteorological variables, perturbation analyses in chemical transport models (CTMs), and CTM simulations driven by general circulation model (GCM) simulations of 21st-century climate change. We review these different approaches and their results. The future climate is expected to be more stagnant, due to a weaker global circulation and a decreasing frequency of mid-latitude cyclones. The observed correlation between surface ozone and temperature in polluted regions points to a detrimental effect of warming. Coupled GCM-CTM studies find that climate change alone will increase summertime surface ozone in polluted regions by 1-10 ppb over the coming decades, with the largest effects in urban areas and during pollution episodes. This climate penalty means that stronger emission controls will be needed to meet a given air quality standard. Higher water vapor in the future climate is expected to decrease the ozone background, so that pollution and background ozone have opposite sensitivities to climate change. The effect of climate change on particulate matter (PM) is more complicated and uncertain than for ozone. Precipitation frequency and mixing depth are important driving factors but projections for these variables are often unreliable. GCM-CTM studies find that climate change will affect PM concentrations in polluted environments by AE0.1-1 mg m À3 over the coming decades. Wildfires fueled by climate change could become an increasingly important PM source. Major issues that should be addressed in future research include the ability of GCMs to simulate regional air pollution meteorology and its sensitivity to climate change, the response of natural emissions to climate change, and the atmospheric chemistry of isoprene. Research needs to be undertaken on the effect of climate change on mercury, particularly in view of the potential for a large increase in mercury soil emissions driven by increased respiration in boreal ecosystems.

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“…We must, however, put strong limitations on the magnitude of predicted changes in soil Hg densities because using direct (i.e., linear) relationships between soil Hg and C changes that result from our model implementation are highly unlikely in reality. For example, linear responses between Hg and C changes might be expected upon complete loss of both Hg and organic C pools (e.g., that may occur in surface organic horizons during wildfires) where significant Hg losses have in fact been observed (Artaxo et al, 2000;Brunke et al, 2001;Friedli et al, 2001;Sigler et al, 2003;Turetsky et al, 2006;. In contrast, however, the few experimental studies that correspondingly measured the fate of Hg upon C mineralisation indicate that only a small fraction of Hg may be subject to volatilisation losses upon evasion of CO 2 (Fritsche et al, 2008;Obrist et al, 2010b), which would indicate a much smaller magnitude of soil Hg losses compared to that of C. The biogeochemistry of terrestrial Hg is very complex, including various deposition and emission pathways (Graydon , 2008b;Gustin et al, 2008), redox transformations between volatile and non-volatile Hg forms (Lalonde et al, 2001;Obrist et al, 2010a), and methylation and demethylation processes (Ullrich et al, 2001).…”

Section: Sensitivity To Change In Air Temperaturementioning

confidence: 99%

Modelling the sensitivity of soil mercury storage to climate-induced changes in soil carbon pools

2013

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Substantial amounts of mercury (Hg) in the terrestrial environment reside in soils and are associated with soil organic carbon (C) pools, where they accumulated due to increased atmospheric deposition resulting from anthropogenic activities. The purpose of this study was to examine potential sensitivity of surface soil Hg pools to global change variables, particularly affected by predicted changes in soil C pools, in the contiguous US. To investigate, we included a soil Hg component in the Community Land Model based on empirical statistical relationships between soil Hg / C ratios and precipitation, latitude, and clay; and subsequently explored the sensitivity of soil C and soil Hg densities (i.e., areal-mass) to climate scenarios in which we altered annual precipitation, carbon dioxide (CO₂) concentrations and temperature.

Our model simulations showed that current sequestration of Hg in the contiguous US accounted for 15 230 metric tons of Hg in the top 0–40 cm of soils, or for over 300 000 metric tons when extrapolated globally. In the simulations, US soil Hg pools were most sensitive to changes in precipitation because of strong effects on soil C pools, plus a direct effect of precipitation on soil Hg / C ratios. Soil Hg pools were predicted to increase beyond present-day values following an increase in precipitation amounts and decrease following a reduction in precipitation. We found pronounced regional differences in sensitivity of soil Hg to precipitation, which were particularly high along high-precipitation areas along the West and East Coasts. Modelled increases in CO₂ concentrations to 700 ppm stimulated soil C and Hg accrual, while increased air temperatures had small negative effects on soil C and Hg densities. The combined effects of increased CO₂, increased temperature and increased or decreased precipitation were strongly governed by precipitation and CO₂ showing pronounced regional patterns. Based on these results, we conclude that the combination of precipitation and CO₂ should be emphasised when assessing how climate-induced changes in soil C may affect sequestration of Hg in soils

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Wildfires threaten mercury stocks in northern soils

Cited by 118 publications

References 37 publications

How important is biomass burning in Canada to mercury contamination?

How important is biomass burning in Canada to mercury contamination?

Effect of climate change on air quality

Modelling the sensitivity of soil mercury storage to climate-induced changes in soil carbon pools

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