The Role of Mercury Redox Reactions in Snow on Snow-to-Air Mercury Transfer

Lalonde, Janick D.; Poulain, Alexandre J.; Amyot, Marc

doi:10.1021/es010786g

Cited by 194 publications

(218 citation statements)

References 15 publications

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“…Furthermore, several authors have already pointed out the question of mercury reactivity in snow [61][62]. Photoreduction processes and/or photo-induced reductions of divalent mercury complexes could be the chemical pathways at the origin of Hg° reemission from the snow-pack.…”

Section: Mercury Chemistry In Snowmentioning

confidence: 99%

Mercury as a global pollutant

Poissant¹,

Dommergue

Ferrari

2002

J. Phys. IV France

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Abstract. Mercury may be one of the best-documented hazardous substances utilised by man. Still the uncovering of the global human impacts on the environment through the use and mobilisation of mercury cannot be considered complete. Recent mercury depletion events observed in the Arctic have opened the horizon to numerous new aspects on mercury fate and cycling in the environment. This chapter browses various aspects of the extremely complex cycling and fate of mercury in the perspective of mercury as a global pollutant and discusses some new emerging research fields in mercury.

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Section: Mercury Chemistry In Snowmentioning

confidence: 99%

Mercury as a global pollutant

Poissant¹,

Dommergue

Ferrari

2002

J. Phys. IV France

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“…3b, Faïn et al, 2013). Such Hg 0 gas concentration enrichments were attributed to strong photochemically initiated reduction of snow-bound Hg II to Hg 0 gas (Lalonde et al, 2002). The implications of Hg 0 gas production www.the-cryosphere.net/12/1939/2018/ The Cryosphere, 12,[1939][1940][1941][1942][1943][1944][1945][1946][1947][1948][1949][1950][1951][1952][1953][1954][1955][1956]2018 is that subsequent volatilization of the Hg 0 gas from the porous snowpack to the atmosphere can alleviate atmospheric deposition loads, and it is estimated that globally 50 % of snowbound Hg is volatilized back to the atmosphere prior to snowmelt (Corbitt et al, 2011).…”

Section: Gaseous Hg 0 Concentration Profilesmentioning

confidence: 98%

“…This was a period when AMDEs occurred at this site, as evident by depletions of atmospheric Hg 0 gas with formation and deposition of oxidized atmospheric Hg II Van Dam et al, 2013). Surface snow Hg concentration enhancements during AMDEs are commonly reported in polar regions, with at times Hg concentration enhancements up to 100 times the base concentration in the Arctic (Lalonde et al, 2002;Lindberg et al, 1998;Poulain et al, 2004;Steffen et al, 2002). The presence of AMDEs generally results in increased deposition of Hg to snow and ice surfaces, yet such additional deposition often is short-lived due to the photochemical re-emission of Hg 0 gas (Kirk et al, 2006).…”

Section: Seasonal Patternsmentioning

confidence: 99%

“…The snowpack hence forms a critical interface between the Arctic atmosphere, tundra ecosystems, and underlying tundra soils. Trace gas exchanges between the atmosphere and the tundra are modulated by sinks and sources below and within snowpack, by snow diffusivity, snow height, and snow porosity (Dominé and Shepson, 2002;Lalonde et al, 2002;Monson et al, 2006). The snowpack accumulates nutrients, pollutants, and impurities that are deposited by snowfall and dry deposition processes, all of which can subsequently be transported to underlying ecosystems during snowmelt (Bergin et al, 1995;Uematsu et al, 2000).…”

Section: Introductionmentioning

confidence: 99%

“…In particular, temperate and Arctic studies have shown that the snowpack can serve as sink or source of Hg 0 gas , whereby photochemical reduction of snow-bound Hg II can produce Hg 0 gas , and oxidation processes can reversely scavenge atmospheric Hg 0 gas in snow (Faïn et al, 2013;Lalonde et al, 2002;Mann et al, 2011). Photochemical reactions occur primarily in the top 10 cm of the snowpack, where sunlight radiation transmits and is absorbed and scattered by snow crystals (Faïn et al, 2007;King and Simpson, 2001).…”

Section: Introductionmentioning

confidence: 99%

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Mercury in the Arctic tundra snowpack: temporal and spatial concentration patterns and trace gas exchanges

Agnan¹,

Douglas²,

Helmig³

et al. 2018

The Cryosphere

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Abstract. In the Arctic, the snowpack forms the major interface between atmospheric and terrestrial cycling of mercury (Hg), a global pollutant. We investigated Hg dynamics in an interior Arctic tundra snowpack in northern Alaska during two winter seasons. Using a snow tower system to monitor Hg trace gas exchange, we observed consistent concentration declines of gaseous elemental Hg (Hg 0 gas ) from the atmosphere to the snowpack to soils. The snowpack itself was unlikely a direct sink for atmospheric Hg 0 gas . In addition, there was no evidence of photochemical reduction of Hg II to Hg 0 gas in the tundra snowpack, with the exception of short periods during late winter in the uppermost snow layer. The patterns in this interior Arctic snowpack thus differ substantially from observations in Arctic coastal and temperate snowpacks. We consistently measured low concentrations of both total and dissolved Hg in snowpack throughout the two seasons. Chemical tracers showed that Hg was mainly associated with local mineral dust and regional marine sea spray inputs. Mass balance calculations show that the snowpack represents a small reservoir of Hg, resulting in low inputs during snowmelt. Taken together, the results from this study suggest that interior Arctic snowpacks are negligible sources of Hg to the Arctic.

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A mass budget for mercury and methylmercury in the Arctic Ocean

Soerensen

Jacob

Schartup

et al. 2016

Global Biogeochemical Cycles

117

155

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Elevated biological concentrations of methylmercury (MeHg), a bioaccumulative neurotoxin, are observed throughout the Arctic Ocean, but major sources and degradation pathways in seawater are not well understood. We develop a mass budget for mercury species in the Arctic Ocean based on available data since 2004 and discuss implications and uncertainties. Our calculations show that high total mercury (Hg) in Arctic seawater relative to other basins reflect large freshwater inputs and sea ice cover that inhibits losses through evasion. We find that most net MeHg production (20 Mg a À1 ) occurs in the subsurface ocean (20-200 m). There it is converted to dimethylmercury (Me 2 Hg: 17 Mg a À1 ), which diffuses to the polar mixed layer and evades to the atmosphere (14 Mg a À1 ). Me 2 Hg has a short atmospheric lifetime and rapidly degrades back to MeHg. We postulate that most evaded Me 2 Hg is redeposited as MeHg and that atmospheric deposition is the largest net MeHg source (8 Mg a À1 ) to the biologically productive surface ocean. MeHg concentrations in Arctic Ocean seawater are elevated compared to lower latitudes. Riverine MeHg inputs account for approximately 15% of inputs to the surface ocean (2.5 Mg a À1 ) but greater importance in the future is likely given increasing freshwater discharges and permafrost melt. This may offset potential declines driven by increasing evasion from ice-free surface waters. Geochemical model simulations illustrate that for the most biologically relevant regions of the ocean, regulatory actions that decrease Hg inputs have the capacity to rapidly affect aquatic Hg concentrations.

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The Role of Mercury Redox Reactions in Snow on Snow-to-Air Mercury Transfer

Cited by 194 publications

References 15 publications

Mercury as a global pollutant

Mercury as a global pollutant

Mercury in the Arctic tundra snowpack: temporal and spatial concentration patterns and trace gas exchanges

A mass budget for mercury and methylmercury in the Arctic Ocean

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