Multi-model study of mercury dispersion in the atmosphere: atmospheric processes and model evaluation

Travnikov, Oleg; Angot, Hélène; Artaxo, Paulo; Bencardino, Mariantonia; Bieser, Johannes; D’Amore, Francesco; Dastoor, Ashu; Simone, Francesco De; Diéguez, María del Carmen; Dommergue, Aurélien; Ebinghaus, Ralf; Feng, Xizeng; Gencarelli, Christian N.; Hedgecock, Ian M.; Magand, Olivier; Martin, Lynwill; Matthias, Volker; Mashyanov, Nikolay; Pirrone, Nicola; Ramachandran, Ramesh; Read, Katie A.; Ryjkov, Andrei; Selin, Noelle E.; Sena, Fabrizio; Song, Shaojie; Sprovieri, Francesca; Wip, Dennis; Wängberg, Ingvar; Yang, Xin

doi:10.5194/acp-17-5271-2017

Cited by 78 publications

(83 citation statements)

References 116 publications

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“…Atmospheric redox chemistry of Hg plays an important role in understanding Hg transport and deposition in the atmosphere. However, mechanisms of Hg oxidation in the atmosphere are not well understood, causing uncertainty in the simulation results of Hg chemical transport models (Ariya et al, ; Gencarelli et al, ; Pacyna et al, ; Travnikov et al, ; L. M. Zhang et al, ). Observational evidence exists that the Br‐mediated oxidation pathway plays a dominant role in GEM oxidation in certain atmospheric environments (e.g., the marine boundary, polar regions, and the upper troposphere; Ariya et al, ; Gratz et al, ; Holmes et al, ; Horowitz et al, ).…”

Section: Methodsmentioning

confidence: 99%

Assessment of Regional Mercury Deposition and Emission Outflow in Mainland China

et al. 2018

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Mainland China is the largest emission region of anthropogenic mercury (Hg) in the world. There have been concerns regarding the emission outflow and chemical transport budget of Hg in the region. Earlier assessments of Hg chemical transport were based on relatively outdated emission data. Recent estimates for anthropogenic (Wu et al., 2016, https://doi.org/10.1021/acs.est.6b04308) and natural Hg emissions (X. Wang, Lin, et al., 2016, https://doi.org/10.5194/acp-16-11125-2016) show substantial differences from earlier emission inventories. In this study, we applied the updated Hg emission estimates to reassess the regional transport budget using Community Multiscale Air Quality‐Hg v5.1. Our results show that the variation of simulated concentration, deposition, and associated emission outflow of Hg are primarily influenced by the spatial‐temporal variation of Hg emissions, monsoon shifts, and particulate matter pollution in China. Total Hg deposition in Mainland China is estimated to be 422 Mg/year, and approximately two thirds of the deposition is contributed by domestic emissions. The net Hg transport budget from Mainland China is 511 Mg/year, contributing to 10% of Hg deposition in other regions of the world. This reassessment points to a ~25% reduction in total annual outflow compared to the previous estimate by Lin et al. (2010, https://doi.org/10.5194/acp-10-1853-2010). Such reduction is mainly caused by changes in Hg emission quantity, speciation, and spatial/temporal distributions. More modeling studies focusing on reducing uncertainties of emission inventories and Hg atmospheric chemistry are needed for continuous assessment of Hg emission outflow in this emission‐intensive region.

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Section: Methodsmentioning

confidence: 99%

Assessment of Regional Mercury Deposition and Emission Outflow in Mainland China

et al. 2018

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“…A two-step gas-phase oxidation of GEM by Br is included as an option. Aqueous-phase reactions include oxidation by ozone, chlorine, and hydroxyl radical and reduction via decomposition of sulphite complexes (Van Loon et al, 2000). The model distinguishes in-cloud and sub-cloud wet deposition of PBM and GOM based on empirical data.…”

Section: Glemos (Global Emep Multi-media Modeling System)mentioning

confidence: 99%

“…The model is based on a three-dimensional Eulerian atmospheric chemistry and transport modeling system that simulates Hg, ozone, particulate matter, acid deposition, and visibility simultaneously. The model components and scientific backgrounds have been documented elsewhere (Bullock and Brehme, 2002;Bullock et al, 2008;Travnikov et al, 2010). A spin-up period of 10 days is used to eliminate the impact of initial conditions for atmospheric oxidants (O 3 and OH) that react with mercury.…”

Section: Cmaq-hemmentioning

confidence: 99%

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Multi-model study of mercury dispersion in the atmosphere: vertical and interhemispheric distribution of mercury species

et al. 2017

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Abstract. Atmospheric chemistry and transport of mercury play a key role in the global mercury cycle. However, there are still considerable knowledge gaps concerning the fate of mercury in the atmosphere. This is the second part of a model intercomparison study investigating the impact of atmospheric chemistry and emissions on mercury in the atmosphere. While the first study focused on ground-based observations of mercury concentration and deposition, here we investigate the vertical and interhemispheric distribution and speciation of mercury from the planetary boundary layer to the lower stratosphere. So far, there have been few model studies investigating the vertical distribution of mercury, mostly focusing on single aircraft campaigns. Here, we present a first comprehensive analysis based on various aircraft observations in Europe, North America, and on intercontinental flights.The investigated models proved to be able to reproduce the distribution of total and elemental mercury concentrations in the troposphere including interhemispheric trends. One key aspect of the study is the investigation of mercury oxidation in the troposphere. We found that different chemistry schemes were better at reproducing observed oxidized mercury patterns depending on altitude. High concentrations of oxidized mercury in the upper troposphere could be reproduced with oxidation by bromine while elevated concentrations in the lower troposphere were better reproduced by OH and ozone chemistry. However, the results were not always conclusive as the physical and chemical parameterizations in the chemistry transport models also proved to have a substantial impact on model results.

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“…Here, we use the 2009-2012 AMNet observations, as these data are publicly available. AMNet had 23 sites over the continental US and eastern Canada (Nova Scotia) operational during this period (Table S2 in Ground-based measurements of Hg wet deposition and Hg(II) surface concentration have been made as part of the Global Mercury Observations System (GMOS) network (Angot et al, 2014;Wängberg et al, 2016;Sprovieri et al, 2016Sprovieri et al, , 2017Travnikov et al, 2017) and at sites in Europe (Weigelt et al, 2013), Canada, and East Asia (Sheu et al, 2010;Sheu and Lin, 2013;Fu et al, 2015Fu et al, , 2016b. We use the 2013-2014 measurements wherever available but use all sites with 1 year or more of observations.…”

Section: Introductionmentioning

confidence: 99%

Subtropical subsidence and surface deposition of oxidized mercury produced in the free troposphere

Shah

Jaeglé

2017

Atmos. Chem. Phys.

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Abstract. Oxidized mercury (Hg(II)) is chemically produced in the atmosphere by oxidation of elemental mercury and is directly emitted by anthropogenic activities. We use the GEOS-Chem global chemical transport model with gaseous oxidation driven by Br atoms to quantify how surface deposition of Hg(II) is influenced by Hg(II) production at different atmospheric heights. We tag Hg(II) chemically produced in the lower (surface-750 hPa), middle (750-400 hPa), and upper troposphere (400 hPa-tropopause), in the stratosphere, as well as directly emitted Hg(II). We evaluate our 2-year simulation (2013)(2014) against observations of Hg(II) wet deposition as well as surface and free-tropospheric observations of Hg(II), finding reasonable agreement. We find that Hg(II) produced in the upper and middle troposphere constitutes 91 % of the tropospheric mass of Hg(II) and 91 % of the annual Hg(II) wet deposition flux. This large global influence from the upper and middle troposphere is the result of strong chemical production coupled with a long lifetime of Hg(II) in these regions. Annually, 77-84 % of surface-level Hg(II) over the western US, South America, South Africa, and Australia is produced in the upper and middle troposphere, whereas 26-66 % of surface Hg(II) over the eastern US, Europe, and East Asia, and South Asia is directly emitted. The influence of directly emitted Hg(II) near emission sources is likely higher but cannot be quantified by our coarse-resolution global model (2 • latitude × 2.5 • longitude). Over the oceans, 72 % of surface Hg(II) is produced in the lower troposphere because of higher Br concentrations in the marine boundary layer. The global contribution of the upper and middle troposphere to the Hg(II) dry deposition flux is 52 %. It is lower compared to the contribution to wet deposition because dry deposition of Hg(II) produced aloft requires its entrainment into the boundary layer, while rain can scavenge Hg(II) from higher altitudes more readily. We find that 55 % of the spatial variation of Hg wet deposition flux observed at the Mercury Deposition Network sites is explained by the combined variation of precipitation and Hg(II) produced in the upper and middle troposphere. Our simulation points to a large role of the dry subtropical subsidence regions. Hg(II) present in these regions accounts for 74 % of Hg(II) at 500 hPa over the continental US and more than 60 % of the surface Hg(II) over high-altitude areas of the western US. Globally, it accounts for 78 % of the tropospheric Hg(II) mass and 61 % of the total Hg(II) deposition. During the Nitrogen, Oxidants, Mercury, and Aerosol Distributions, Sources, and Sinks (NOMADSS) aircraft campaign, the contribution of Hg(II) from the dry subtropical regions was found to be 75 % when measured Hg(II) exceeded 250 pg m −3 . Hg(II) produced in the upper and middle troposphere subsides in the anticyclones, where the dry conditions inhibit the loss of Hg(II). Our results highlight the importance the subtropical anticyclones as the primary conduits for t...

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Multi-model study of mercury dispersion in the atmosphere: atmospheric processes and model evaluation

Cited by 78 publications

References 116 publications

Assessment of Regional Mercury Deposition and Emission Outflow in Mainland China

Assessment of Regional Mercury Deposition and Emission Outflow in Mainland China

Multi-model study of mercury dispersion in the atmosphere: vertical and interhemispheric distribution of mercury species

Subtropical subsidence and surface deposition of oxidized mercury produced in the free troposphere

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