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Atmospheric Mercury Transfer to Peat Bogs Dominated by Gaseous Elemental Mercury Dry Deposition

Enrico, Maxime and Le Roux, Gaël and Marusczak, Nicolas and Heimbürger, Lars-Éric and Claustres, Adrien and Fu, Xuewu and Sun, Ruoyu and Sonke, Jeroen Atmospheric Mercury Transfer to Peat Bogs Dominated by Gaseous Elemental Mercury Dry Deposition. (2016) Environmental Science & Technology, 50 (5). 2405-2412. ISSN 0013-936X

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Official URL: https://doi.org/10.1021/acs.est.5b06058

Abstract

Gaseous elemental mercury (GEM) is the dominant form of mercury in the atmosphere. Its conversion into oxidized gaseous and particulate forms is thought to drive atmospheric mercury wet deposition to terrestrial and aquatic ecosystems, where it can be subsequently transformed into toxic methylmercury. The contribution of mercury dry deposition is however largely unconstrained. Here we examine mercury mass balance and mercury stable isotope composition in a peat bog ecosystem. We find that isotope signatures of living sphagnum moss (Δ199Hg = −0.11 ± 0.09‰, Δ200Hg = 0.03 ± 0.02‰, 1σ) and recently accumulated peat (Δ199Hg = −0.22 ± 0.06‰, Δ200Hg = 0.00 ± 0.04‰, 1σ) are characteristic of GEM (Δ199Hg = −0.17 ± 0.07‰, Δ200Hg = −0.05 ± 0.02‰, 1σ), and differs from wet deposition (Δ199Hg = 0.73 ± 0.15‰, Δ200Hg = 0.21 ± 0.04‰, 1σ). Sphagnum covered during three years by transparent and opaque surfaces, which eliminate wet deposition, continue to accumulate Hg. Sphagnum Hg isotope signatures indicate accumulation to take place by GEM dry deposition, and indicate little photochemical re-emission. We estimate that atmospheric mercury deposition to the peat bog surface is dominated by GEM dry deposition (79%) rather than wet deposition (21%). Consequently, peat deposits are potential records of past atmospheric GEM concentrations and isotopic composition.

Item Type:Article
Audience (journal):International peer-reviewed journal
Uncontrolled Keywords:
Institution:French research institutions > Centre National de la Recherche Scientifique - CNRS (FRANCE)
Université de Toulouse > Institut National Polytechnique de Toulouse - INPT (FRANCE)
French research institutions > Institut de Recherche pour le Développement - IRD (FRANCE)
Université de Toulouse > Université Toulouse III - Paul Sabatier - UPS (FRANCE)
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Deposited By: Gael LE ROUX
Deposited On:19 Nov 2018 10:19

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