Global simulation of atmospheric mercury concentrations and deposition fluxes

Shia, Run‐Lie; Seigneur, Christian; Pai, Prasad; Ko, Malcolm K. W.; Sze, Nien Dak

doi:10.1029/1999jd900354

Cited by 122 publications

(81 citation statements)

References 68 publications

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“…While there has been a major body of work in the last 50 years collecting information about the distribution, transport and speciation of Hg in the environment (e.g., Shia et al, 1999;Mason and Sheu, 2002;UNEP, 2002;Nriagu and Becker, 2003;Fitzgerald et al, 2007;Selin, 2009;Lavoie et al, 2013;Ferris and Essington, 2014;Ganguli et al, 2014), data from developing country locations isolated/remote from major Hg sources are quite limited. In the South Pacific region, data on Hg are relatively uncommon.…”

Section: Hg Concentrations Have Been Identified In Sediments In Variomentioning

confidence: 99%

Mercury (Hg) speciation in coral reef systems of remote Oceania: Implications for the artisanal fisheries of Tutuila, Samoa Islands

Morrison

Peshut

West

et al. 2015

Marine Pollution Bulletin

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We investigated Hg in muscle tissue of fish species from three trophic levels on fringing reefs of Tutuila (14°S, 171°W), plus water, sediment and turf alga. Accumulation of total Hg in the herbivore Acanthurus lineatus (Acanthuridae, lined surgeonfish, (n =40)) was negligible at 1.05 (±0.04) ngg -1 wet-weight, (~65% occurring as methyl Hg). The mid-level carnivore Parupeneus spp. (Mullidae, goatfishes (n =10)) had total Hg 29.8 (±4.5) ngg -1 wet-weight (~99% as methyl Hg). Neither A. lineatus or Parupeneus spp. showed a propensity to accumulate Hg based on body size. Both groups were assigned a status of "un-restricted" for monthly consumption limits for non-carcinogenic health endpoints for methyl Hg. The top-level carnivore Sphyraena qenie (Sphyraenidae, blackfin barracuda, n =3) had muscle tissue residues of 105, 650 and 741ngg -1 wetweight (100% methyl Hg, with increasing concentration with body mass, suggesting that S. qenie >15kg would have a recommendation of "no consumption".

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Section: Hg Concentrations Have Been Identified In Sediments In Variomentioning

confidence: 99%

Mercury (Hg) speciation in coral reef systems of remote Oceania: Implications for the artisanal fisheries of Tutuila, Samoa Islands

Morrison

Peshut

West

et al. 2015

Marine Pollution Bulletin

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“…Atmospheric observations imply that oxidation of Hg 0 to Hg II must be photochemical (Shia et al, 1999;Selin et al, 2007). Models generally assume that gas-phase OH and ozone are the main oxidants, and also include aqueous-phase reduction of Hg II to Hg 0 that competes with deposition as a sink for Hg II (Bergan and Rodhe, 2001;Petersen et al, 2001;Cohen et al, 2004;Lin et al, 2006;Seigneur et al, 2006;Selin et al, 2007;Pongprueksa et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

Global atmospheric model for mercury including oxidation by bromine atoms

et al. 2010

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Abstract. Global models of atmospheric mercury generally assume that gas-phase OH and ozone are the main oxidants converting Hg 0 to Hg II and thus driving mercury deposition to ecosystems. However, thermodynamic considerations argue against the importance of these reactions. We demonstrate here the viability of atomic bromine (Br) as an alternative Hg 0 oxidant. We conduct a global 3-D simulation with the GEOS-Chem model assuming gas-phase Br to be the sole Hg 0 oxidant (Hg + Br model) and compare to the previous version of the model with OH and ozone as the sole oxidants (Hg + OH/O 3 model). We specify global 3-D Br concentration fields based on our best understanding of tropospheric and stratospheric Br chemistry. In both the Hg + Br and Hg + OH/O 3 models, we add an aqueous photochemical reduction of Hg II in cloud to impose a tropospheric lifetime for mercury of 6.5 months against deposition, as needed to reconcile observed total gaseous mercury (TGM) concentrations with current estimates of anthropogenic emissions. This added reduction would not be necessary in the Hg + Br model if we adjusted the Br oxidation kinetics downward within their range of uncertainty. We find that the Hg + Br and Hg + OH/O 3 models are equally capable of reproducing the spatial distribution of TGM and its seasonal cycle at northern mid-latitudes. The Hg + Br model shows a steeper decline of TGM concentrations from the tropics to southern mid-latitudes. Only the Hg + Br model can reproduce the springtime depletion and summer rebound of TGM observed at polar sites; the snowpack component of GEOS-Chem suggests that 40% of Hg II deposited to snow in the Arctic is transferred to the ocean and land reservoirs, amounting to aCorrespondence to: C. D. Holmes (cdholmes@post.harvard.edu) net deposition flux to the Arctic of 60 Mg a −1 . Summertime events of depleted Hg 0 at Antarctic sites due to subsidence are much better simulated by the Hg + Br model. Model comparisons to observed wet deposition fluxes of mercury in the US and Europe show general consistency. However the Hg + Br model does not capture the summer maximum over the southeast US because of low subtropical Br concentrations while the Hg + OH/O 3 model does. Vertical profiles measured from aircraft show a decline of Hg 0 above the tropopause that can be captured by both the Hg + Br and Hg + OH/O 3 models, except in Arctic spring where the observed decline is much steeper than simulated by either model; we speculate that oxidation by Cl species might be responsible. The Hg + Br and Hg + OH/O 3 models yield similar global budgets for the cycling of mercury between the atmosphere and surface reservoirs, but the Hg + Br model results in a much larger fraction of mercury deposited to the Southern Hemisphere oceans.

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“…GISS-CTM: Shia et al, 1999;GEOS-Chem: Selin et al, 2007; GRAHM: Dastoor and Larocque, 2004). However, these models often have coarse horizontal resolution (∼ 200-1000 km) and thus lack the resolution needed for detailed evaluation at the regional scale.…”

Section: Introductionmentioning

confidence: 99%

Nested-grid simulation of mercury over North America

et al. 2012

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Abstract. We have developed a new nested-grid mercury (Hg) simulation over North America with a 1/2 • latitude by 2/3 • longitude horizontal resolution employing the GEOSChem global chemical transport model. Emissions, chemistry, deposition, and meteorology are self-consistent between the global and nested domains. Compared to the global model (4 • latitude by 5 • longitude), the nested model shows improved skill at capturing the high spatial and temporal variability of Hg wet deposition over North America observed by the Mercury Deposition Network (MDN) in [2008][2009]. The nested simulation resolves features such as higher deposition due to orographic precipitation, land/ocean contrast and and predicts more efficient convective rain scavenging of Hg over the southeast United States. However, the nested model overestimates Hg wet deposition over the Ohio River Valley region (ORV) by 27 %. We modify anthropogenic emission speciation profiles in the US EPA National Emission Inventory (NEI) to account for the rapid inplume reduction of reactive to elemental Hg (IPR simulation). This leads to a decrease in the model bias to −2.3 % over the ORV region. Over the contiguous US, the correlation coefficient (r) between MDN observations and our IPR simulation increases from 0.60 to 0.78. The IPR nested simulation generally reproduces the seasonal cycle in surface concentrations of speciated Hg from the Atmospheric Mercury Network (AMNet) and Canadian Atmospheric Mercury Network (CAMNet). In the IPR simulation, annual mean gaseous and particulate-bound Hg(II) are within 140 % and 11 % of observations, respectively. In contrast, the simulation with unmodified anthropogenic Hg speciation profiles overestimates these observations by factors of 4 and 2 for gaseous and particulate-bound Hg(II), respectively. The nested model shows improved skill at capturing the horizontal variability of Hg observed over California during the ARCTAS aircraft campaign. The nested model suggests that North American anthropogenic emissions account for 10-22 % of Hg wet deposition flux over the US, depending on the anthropogenic emissions speciation profile assumed. The modeled percent contribution can be as high as 60 % near large point sources in ORV. Our results indicate that the North American anthropogenic contribution to dry deposition is 13-20 %.

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Global simulation of atmospheric mercury concentrations and deposition fluxes

Cited by 122 publications

References 68 publications

Mercury (Hg) speciation in coral reef systems of remote Oceania: Implications for the artisanal fisheries of Tutuila, Samoa Islands

Mercury (Hg) speciation in coral reef systems of remote Oceania: Implications for the artisanal fisheries of Tutuila, Samoa Islands

Global atmospheric model for mercury including oxidation by bromine atoms

Nested-grid simulation of mercury over North America

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