Nested-grid simulation of mercury over North America

Zhang, Y.; Jaeglé, Lyatt; Donkelaar, Aaron van; Martin, Randall V.; Holmes, Christopher D.; Amos, H. M.; Wang, Q.; Talbot, R. W.; Artz, Richard S.; Brooks, Steve; Luke, Winston T.; Holsen, Thomas M.; Felton, Dirk; Miller, Eric K.; Perry, K. D.; Schmeltz, D.; Steffen, Alexandra; Tordon, R.; Weiss-Penzias, P. S.; Zsolway, R.

doi:10.5194/acpd-12-2603-2012

Cited by 26 publications

(55 citation statements)

References 78 publications

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“…Here we follow the emission speciation of Y. Zhang et al (2011), which is consistent with the above studies and greatly reduces the model bias compared to observations of RGM and PBM (see Sect. 4).…”

Section: H M Amos Et Al: Gas-particle Partitioning Of Atmospheric supporting

confidence: 68%

“…Several model studies also provide support for in-plume reduction of Hg(II) emitted from power plants (Seigneur et al, 2003;Lohman et al, 2006;Seigneur et al, 2006;Vijayaraghavan et al, 2008;Kos et al, 2011;Y. Zhang et al, 2011).…”

Section: H M Amos Et Al: Gas-particle Partitioning Of Atmospheric mentioning

confidence: 99%

“…Y. Zhang et al (2011) use a 86.5:9.9:3.6 (1) and (2), not including partitioning into sea-salt aerosol which is treated separately following Holmes et al (2010).…”

Section: H M Amos Et Al: Gas-particle Partitioning Of Atmospheric mentioning

confidence: 99%

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Gas-particle partitioning of atmospheric Hg(II) and its effect on global mercury deposition

Amos

Jacob²,

Holmes³

et al. 2012

Atmos. Chem. Phys.

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412

459

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Abstract. Atmospheric deposition of Hg(II) represents a major input of mercury to surface environments. The phase of Hg(II) (gas or particle) has important implications for deposition. We use long-term observations of reactive gaseous mercury (RGM, the gaseous component of Hg(II)), particle-bound mercury (PBM, the particulate component of Hg(II)), fine particulate matter (PM 2.5 ), and temperature (T ) at five sites in North America to derive an empirical gas-particle partitioning relationship log 10 (K −1 ) = (10±1)-(2500±300)/T where K = (PBM/PM 2.5 )/RGM with PBM and RGM in common mixing ratio units, PM 2.5 in µg m −3 , and T in K. This relationship is within the range of previous work but is based on far more extensive data from multiple sites. We implement this empirical relationship in the GEOS-Chem global 3-D Hg model to partition Hg(II) between the gas and particle phases. The resulting gas-phase fraction of Hg(II) ranges from over 90 % in warm air with little aerosol to less than 10 % in cold air with high aerosol. Hg deposition to high latitudes increases because of more efficient scavenging of particulate Hg(II) by precipitating snow. Model comparison to Hg observations at the North American surface sites suggests that subsidence from the free troposphere (warm air, low aerosol) is a major factor driving the seasonality of RGM, while elevated PBM is mostly associated with high aerosol loads. Simulation of RGM and PBM at these sites is improved by including fast in-plume reduction of Hg(II) emitted from coal combustion and by assuming that anthropogenic particulate Hg(p) behaves as semivolatile Hg(II) rather than as a refractory particulate component. We improve the simulation of Hg wet deposition fluxes in the US relative to a previous version of GEOS-Chem; this largely reflects independent improvement of the washout algorithm. The observed wintertime minimum in wet deposition fluxes is attributed to inefficient snow scavenging of gas-phase Hg(II).

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Section: H M Amos Et Al: Gas-particle Partitioning Of Atmospheric supporting

confidence: 68%

Section: H M Amos Et Al: Gas-particle Partitioning Of Atmospheric mentioning

confidence: 99%

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Gas-particle partitioning of atmospheric Hg(II) and its effect on global mercury deposition

Amos

Jacob²,

Holmes³

et al. 2012

Atmos. Chem. Phys.

Self Cite

412

459

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“…It is possible that GOM and FPBM were scavenged by dry deposition before the precipitation event occurred because of relatively higher contributions of GOM and PBM to Hg dry deposition at MD08 and OH02 than sites without point sources [Zhang et al, 2012b]. These results share similar findings with modeled Hg deposition using the GEOS-Chem model that suggested domestic anthropogenic sources only contributed 10-22% of the total Hg wet deposition in the U.S. [Zhang et al, 2012c]. Aside from local Hg point sources, other sources and processes may affect the air concentrations of GOM and FPBM, which subsequently affects %GOM and %FPBM.…”

Section: 1002/2015jd023769supporting

confidence: 80%

“…Mercury transport models have been evaluated using monitored wet deposition data; however, most models do not include coarse PBM (CPBM) in the deposition budget since particle-bound Hg is typically treated as a fine aerosol [Selin et al, 2007;Bullock et al, 2008;Pongprueksa et al, 2008;Amos et al, 2012;Holloway et al, 2012;Zhang et al, 2012a;Kos et al, 2013]. Although most model results are comparable to mercury wet deposition measurements, the omission of CPBM is another potential explanation for the overpredicted concentrations of GOM and fine PBM (<2.5 μm) in many mercury transport models [Amos et al, 2012;Holloway et al, 2012;Kos et al, 2013;Zhang et al, 2012aZhang et al, , 2012c. Measurements of CPBM indicate that the coarse Hg fraction of total particulate mercury at two sites in New Hampshire can range from 0.35 to 0.6 depending on the season and year sampled [Feddersen et al, 2012].…”

Section: Introductionmentioning

confidence: 93%

Relative contributions of gaseous oxidized mercury and fine and coarse particle‐bound mercury to mercury wet deposition at nine monitoring sites in North America

Cheng¹,

Zhang²,

Mao

2015

JGR Atmospheres

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Relative contributions to mercury wet deposition by gaseous oxidized mercury (%GOM) and fine and coarse particle-bound mercury (%FPBM and %CPBM) were estimated making use of monitored FPBM air concentration and mercury wet deposition at nine North American locations. Scavenging ratios of particulate inorganic ions (K + and Ca 2+ , Mg 2+ and Na + ) were used as a surrogate for those of FPBM and CPBM, respectively. FPBM and CPBM were estimated to contribute 8-36% and 5-27%, respectively, depending on the location, to total wet deposition. The rest of the 39-87% was attributed to the contribution of GOM. The average %GOM, %FPBM and %CPBM among all locations were 65%, 17%, and 18%, respectively. The relative distributions of %GOM, %FPBM, and %CPBM were influenced by Hg(II) gas-particle partitioning, urban site characteristics, and precipitation type. At the regional scale, %GOM dominated over %FPBM and %CPBM. However, the sum of FPBM and CPBM contributed to nearly half of the total Hg wet deposition in urban areas, which was greater than other site categories and is attributed to higher FPBM air concentrations. At four locations, %FPBM exceeded %GOM during winter in contrast to summer, suggesting the efficient snow scavenging of aerosols. The results from this study are useful in improving mercury transport models since most of these models do not estimate CPBM, but frequently use monitored mercury wet deposition data for model evaluation.

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Biogeochemical drivers of the fate of riverine mercury discharged to the global and Arctic oceans

Zhang

Jacob

Dutkiewicz

et al. 2015

Global Biogeochemical Cycles

114

121

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Rivers discharge 28 ± 13 Mmol yr À1 of mercury (Hg) to ocean margins, an amount comparable to atmospheric deposition to the global oceans. Most of the Hg discharged by rivers is sequestered by burial of benthic sediment in estuaries or the coastal zone, but some is evaded to the atmosphere and some is exported to the open ocean. We investigate the fate of riverine Hg by developing a new global 3-D simulation for Hg in the Massachusetts Institute of Technology ocean general circulation model. The model includes plankton dynamics and carbon respiration (DARWIN project model) coupled to inorganic Hg chemistry. Results are consistent with observed spatial patterns and magnitudes of surface ocean Hg concentrations. We use observational constraints on seawater Hg concentrations and evasion to infer that most Hg from rivers is sorbed to refractory organic carbon and preferentially buried. Only 6% of Hg discharged by rivers (1.8 Mmol yr À1) is transported to the open ocean on a global basis. This fraction varies from a low of 2.6% in East Asia due to the barrier imposed by the Korean Peninsula and Japanese archipelago, up to 25% in eastern North America facilitated by the Gulf Stream. In the Arctic Ocean, low tributary particle loads and efficient degradation of particulate organic carbon by deltaic microbial communities favor a more labile riverine Hg pool. Evasion of Hg to the Arctic atmosphere is indirectly enhanced by heat transport during spring freshet that accelerates sea ice melt and ice rafting. Discharges of 0.23 Mmol Hg yr À1 from Arctic rivers can explain the observed summer maximum in the Arctic atmosphere, and this magnitude of releases is consistent with recent observations. Our work indicates that rivers are major contributors to Hg loads in the Arctic Ocean.

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Nested-grid simulation of mercury over North America

Cited by 26 publications

References 78 publications

Gas-particle partitioning of atmospheric Hg(II) and its effect on global mercury deposition

Gas-particle partitioning of atmospheric Hg(II) and its effect on global mercury deposition

Relative contributions of gaseous oxidized mercury and fine and coarse particle‐bound mercury to mercury wet deposition at nine monitoring sites in North America

Biogeochemical drivers of the fate of riverine mercury discharged to the global and Arctic oceans

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