Progress on Understanding Atmospheric Mercury Hampered by Uncertain Measurements

Jaffe, Daniel A.; Lyman, Seth; Amos, H. M.; Gustin, Mae Sexauer; Huang, Jiaoyan; Selin, Noelle E.; Levin, L.; Schure, Arnout ter; Mason, Robert P.; Talbot, R. W.; Rutter, Andrew P.; Finley, B. D.; Jaeglé, Lyatt; Shah, Viral; McClure, Crystal D.; Ambrose, J. L.; Gratz, Lynne E.; Lindbeŕg, Steven E.; Weiss-Penzias, P. S.; Sheu, Guey Rong; Feddersen, Dara; Horvat, Milena; Dastoor, Ashu; Hynes, Anthony J.; Mao, Huiting; Sonke, Jeroen E.; Šlemr, F.; Fisher, Jenny A.; Ebinghaus, Ralf; Zhang, Yanxu; Edwards, Grant C.

doi:10.1021/es5026432

Cited by 99 publications

(98 citation statements)

References 7 publications

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“…8). This is especially valuable for the analysis of oxidized mercury species, as there is an ongoing discussion about an underestimation of concentrations due to limitations of the current measurement techniques (Lyman et al, 2010Ariya et al, 2015;Gustin et al, 2015;Huang and Gustin, 2015;Jaffe et al, 2014;McClure et al, 2014;Ambrose et al, 2013;Huang et al, 2013;Kos et al, 2013). Generally, the model error can be separated into three parts: the bias, which represents any systematic errors; the variance, which gives the variability around the mean value; and the covariance, which represents the correlation between model and observations (Solazzo and Galmarini, 2016).…”

Section: Model Evaluationmentioning

confidence: 99%

“…While gaseous elemental mercury (GEM) makes up the vast majority of total atmospheric mercury near the surface (Sprovieri et al, 2016 this issue), recent aircraft-based observations have indicated that there is significant oxidation of mercury occurring in the free troposphere (FT) (Brooks et al, 2014;Lyman and Jaffe, 2012;Jaffe et al, 2014;Gratz et al, 2015;Shah et al, 2016). However, apart from GEM no individual mercury compound has been identified so far and the atmospheric oxidized mercury is an unknown mixture of mercury bound to Br, Cl, OH, O, and NO 2 compounds .…”

Section: Introductionmentioning

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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Section: Model Evaluationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

et al. 2017

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“…GOM and PBM measurement uncertainties discussed in recent studies [e.g., Lyman et al, 2010;Kos et al, 2013;Jaffe et al, 2014;Gustin et al, 2015] could affect the estimated GOM and FPBM contributions to total Hg wet deposition. If FPBM measurements were underestimated, contributions to wet deposition would be underestimated for FPBM and CPBM and overestimated for GOM.…”

Section: Model Verification and Uncertaintiesmentioning

confidence: 99%

“…atmos-chem-phys-discuss.net/15/3777/2015/acpd-15-3777-2015-discussion.html). Further research is needed on technologies to reduce measurement uncertainties and improving our understanding of the chemical composition of oxidized mercury and atmospheric mercury cycling processes [Jaffe et al, 2014;Gustin et al, 2015].…”

Section: Model Verification and Uncertaintiesmentioning

confidence: 99%

“…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]. Another reason for the discrepancies between modelpredicted and measurements of GOM and fine PBM could be due to measurement uncertainties and undersampling of GOM [Lyman et al, 2010;Kos et al, 2013;Jaffe et al, 2014;Gustin et al, 2015]. GOM and fine PBM measurement uncertainties are much larger relative to gaseous elemental mercury (GEM) because the exact chemical compositions of these Hg forms have not been determined and therefore calibration methods are not available to assess the accuracy of the measurements.…”

Section: Introductionmentioning

confidence: 99%

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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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Regression modeling of gas-particle partitioning of atmospheric oxidized mercury from temperature data

Cheng

Zhang

Blanchard

2014

J. Geophys. Res. Atmos.

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Models describing the partitioning of atmospheric oxidized mercury (Hg(II)) between the gas and fine particulate phases were developed as a function of temperature. The models were derived from regression analysis of the gas-particle partitioning parameters, defined by a partition coefficient (K p ) and Hg(II) fraction in fine particles (f PBM ) and temperature data from 10 North American sites. The generalized model, log(1/K p ) = 12.69-3485.30(1/T) (R 2 = 0.55; root-mean-square error (RMSE) of 1.06 m 3 /μg for K p ), predicted the observed average K p at 7 of the 10 sites. Discrepancies between the predicted and observed average K p were found at the sites impacted by large Hg sources because the model had not accounted for the different mercury speciation profile and aerosol compositions of different sources. Site-specific equations were also generated from average K p and f PBM corresponding to temperature interval data. The site-specific models were more accurate than the generalized K p model at predicting the observations at 9 of the 10 sites as indicated by RMSE of 0.22-0.5 m 3 /μg for K p and 0.03-0.08 for f PBM . Both models reproduced the observed monthly average values, except for a peak in Hg(II) partitioning observed during summer at two locations. Weak correlations between the site-specific model K p or f PBM and observations suggest the role of aerosol composition, aerosol water content, and relative humidity factors on Hg(II) partitioning. The use of local temperature data to parameterize Hg(II) partitioning in the proposed models potentially improves the estimation of mercury cycling in chemical transport models and elsewhere.

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Progress on Understanding Atmospheric Mercury Hampered by Uncertain Measurements

Cited by 99 publications

References 7 publications

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

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

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

Regression modeling of gas-particle partitioning of atmospheric oxidized mercury from temperature data

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