Our current understanding of major chemical and physical processes affecting mercury dynamics in the atmosphere and at the air-water/terrestrial interfaces

Hynes, Anthony J.; Donohoue, D.; Goodsite, Michael Evan; Hedgecock, Ian M.

doi:10.1007/978-0-387-93958-2_14

Cited by 107 publications

(149 citation statements)

References 65 publications

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“…The experimentally-determined rate constant for the oxidation of Hg 0 by NO 3 has been previously reported to be <4 × 10 −15 cm 3 molecule −1 s −1 by Sommar et al [39] and <7 × 10 −15 cm 3 molecule −1 s −1 by Sumner et al [36] at 1 atm and 298 K. However, based on the new HgO thermochemistry, Hynes et al estimated this reaction to be highly endothermic and, thus, suggested that this oxidation pathway is not viable in the atmosphere [14,49]. Furthermore, theoretical calculations by Dibble et al [47] suggest that NO 3 do not form strong bonds with Hg 0 and therefore is unlikely to initiate gas-phase Hg 0 oxidation reactions.…”

Section: Oxidation Of Hg 0 By Nomentioning

confidence: 96%

“…A recent study by Peleg et al [50] [47,49]; therefore, NO 3 may be involved in the secondary oxidation reaction of unstable Hg I species [50]. More laboratory and theoretical studies are required to assess the role of NO 3 in secondary reactions of Hg 0 oxidation in the real atmosphere, including on atmospherically-relevant surfaces.…”

Section: Oxidation Of Hg 0 By Nomentioning

confidence: 99%

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Recent Advances in Atmospheric Chemistry of Mercury

Ariya

2018

Atmosphere

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Mercury is one of the most toxic metals and has global importance due to the biomagnification and bioaccumulation of organomercury via the aquatic food web. The physical and chemical transformations of various mercury species in the atmosphere strongly influence their composition, phase, transport characteristics and deposition rate to the ground. Modeling efforts to evaluate the mercury cycling in the environment require an accurate understanding of atmospheric mercury chemistry. We focus this article on recent studies (since 2015) on improving our understanding of the atmospheric chemistry of mercury. We discuss recent advances in (i) determining the dominant atmospheric oxidant of elemental mercury (Hg 0 ); (ii) understanding the oxidation reactions of Hg 0 by halogen atoms and by nitrate radical (NO 3 ); (iii) the aqueous reduction of oxidized mercury compounds (Hg II ); and (iv) the heterogeneous reactions of Hg on atmospherically-relevant surfaces. The need for future research to improve understanding of the fate and transformation of mercury in the atmosphere is also discussed.

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Section: Oxidation Of Hg 0 By Nomentioning

confidence: 96%

Section: Oxidation Of Hg 0 By Nomentioning

confidence: 99%

Recent Advances in Atmospheric Chemistry of Mercury

Ariya

2018

Atmosphere

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“…Some of these tests have been studied for other regions (e.g. Travnikov et al, 2016 andBieser et al, 2016) while many other studies have investigated Hg oxidation by ozone or Br (Hynes et al, 2009;Subir et al, 2011Subir et al, , 2012WeissPenzias et al, 2015).…”

Section: Simulations Performedmentioning

confidence: 99%

“…Despite the theoretical doubts of significance of GEM oxidation under atmospheric conditions by O 3 and OH radical, atomic Br is of great relevance to the atmospheric oxidation of GEM is certain (Hynes et al, 2009;Subir et al, 2011Subir et al, , 2012Weiss-Penzias et al, 2015). In particular, for the HgBr * intermediate, Dibble et al (2012) have shown the potential importance of reactions with NO 2 , HOO, ClO and BrO.…”

Section: Mercury Oxidationmentioning

confidence: 99%

Sensitivity model study of regional mercury dispersion in the atmosphere

et al. 2017

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Abstract. Atmospheric deposition is the most important pathway by which Hg reaches marine ecosystems, where it can be methylated and enter the base of food chain. The deposition, transport and chemical interactions of atmospheric Hg have been simulated over Europe for the year 2013 in the framework of the Global Mercury Observation System (GMOS) project, performing 14 different model sensitivity tests using two high-resolution three-dimensional chemical transport models (CTMs), varying the anthropogenic emission datasets, atmospheric Br input fields, Hg oxidation schemes and modelling domain boundary condition input. Sensitivity simulation results were compared with observations from 28 monitoring sites in Europe to assess model performance and particularly to analyse the influence of anthropogenic emission speciation and the Hg 0 (g) atmospheric oxidation mechanism. The contribution of anthropogenic Hg emissions, their speciation and vertical distribution are crucial to the simulated concentration and deposition fields, as is also the choice of Hg 0 (g) oxidation pathway. The areas most sensitive to changes in Hg emission speciation and the emission vertical distribution are those near major sources, but also the Aegean and the Black seas, the English Channel, the Skagerrak Strait and the northern German coast. Considerable influence was found also evident over the Mediterranean, the North Sea and Baltic Sea and some influence is seen over continental Europe, while this difference is least over the north-western part of the modelling domain, which includes the Norwegian Sea and Iceland. The Br oxidation pathway produces more Hg II (g) in the lower model levels, but overall wet deposition is lower in comparison to the simulations which employ an O 3 / OH oxidation mechanism. The necessity to perform continuous measurements of speciated Hg and to investigate the local impacts of Hg emissions and deposition, as well as interactions dependent on land use and vegetation, forests, peat bogs, etc., is highlighted in this study.

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“…As there remains some uncertainty concerning atmospheric Hg oxidation process [35][36][37], simulations were also run including an oxidation mechanism based on bromine, with oxidant fields from the p-Tomcat model [38,39].…”

Section: Methodsmentioning

confidence: 99%

Estimating Uncertainty in Global Mercury Emission Source and Deposition Receptor Relationships

et al. 2017

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Establishing mercury (Hg) source-receptor (SR) relationship matrices provides a tool to improve the understanding of the geographic relationship between regions of Hg release and its eventual deposition. SR relationship matrices are therefore a useful starting point for the development of policies aimed at reducing the impact of Hg emissions from anthropogenic activities (Hg anthr ) on sensitive ecosystems and areas potentially at risk of Hg contamination. A global Chemical Transport Model (CTM) has been used to simulate the emission, transport and fate of Hg anthr from 12 source regions, considering a range of uncertainty in the modelled chemical and physical processes. This ensemble of simulations gives an estimate of the Hg deposition which derives from each source region, as well as an estimate of the uncertainty of the calculated deposition flux. The uncertainty has been calculated using the bootstrap method to estimate this uncertainty in terms of the normalised confidence interval amplitude of the mean (NCIAM). Within the calculated confidence ranges, for almost all regions the contribution to the Hg deposition flux from remote sources is greater than that from domestic sources. Europe and South Asia, where the contributions are statistically indistinguishable, are exceptions, as is East Asia, with local sources dominating the Hg deposition flux. East Asia is the single most important remote source region for most receptor regions. The results yield such high uncertainties in the deposition flux for many receptor regions that the results are unlikely to be taken into consideration by policy makers. This uncertainty is particularly relevant when considering the "domestic" contribution to regional deposition, highlighting the need for more studies to resolve remaining uncertainties in the atmospheric Hg cycle, and Hg anthr emission inventories.

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Our current understanding of major chemical and physical processes affecting mercury dynamics in the atmosphere and at the air-water/terrestrial interfaces

Cited by 107 publications

References 65 publications

Recent Advances in Atmospheric Chemistry of Mercury

Recent Advances in Atmospheric Chemistry of Mercury

Sensitivity model study of regional mercury dispersion in the atmosphere

Estimating Uncertainty in Global Mercury Emission Source and Deposition Receptor Relationships

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