Regional Air Quality Model Application of the Aqueous-Phase Photo Reduction of Atmospheric Oxidized Mercury by Dicarboxylic Acids
In most ecosystems, atmospheric deposition is the primary input of mercury. The total wet deposition of mercury in atmospheric chemistry models is sensitive to parameterization of the aqueous-phase reduction of divalent oxidized mercury (Hg2+). However, most atmospheric chemistry models use a parame...
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| Format: | Article |
| Language: | English |
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MDPI AG
2013-12-01
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| Series: | Atmosphere |
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| Online Access: | http://www.mdpi.com/2073-4433/5/1/1 |
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| author | Jesse O. Bash Annmarie G. Carlton William T. Hutzell O. Russell Bullock Jr. |
| author_facet | Jesse O. Bash Annmarie G. Carlton William T. Hutzell O. Russell Bullock Jr. |
| author_sort | Jesse O. Bash |
| collection | DOAJ |
| description | In most ecosystems, atmospheric deposition is the primary input of mercury. The total wet deposition of mercury in atmospheric chemistry models is sensitive to parameterization of the aqueous-phase reduction of divalent oxidized mercury (Hg2+). However, most atmospheric chemistry models use a parameterization of the aqueous-phase reduction of Hg2+ that has been shown to be unlikely under normal ambient conditions or use a non mechanistic value derived to optimize wet deposition results. Recent laboratory experiments have shown that Hg2+ can be photochemically reduced to elemental mercury (Hg) in the aqueous-phase by dissolved organic matter and a mechanism and the rate for Hg2+ photochemical reduction by dicarboxylic acids (DCA) has been proposed. For the first time in a regional scale model, the DCA mechanism has been applied. The HO2-Hg2+ reduction mechanism, the proposed DCA reduction mechanism, and no aqueous-phase reduction (NAR) of Hg2+ are evaluated against weekly wet deposition totals, concentrations and precipitation observations from the Mercury Deposition Network (MDN) using the Community Multiscale Air Quality (CMAQ) model version 4.7.1. Regional scale simulations of mercury wet deposition using a DCA reduction mechanism evaluated well against observations, and reduced the bias in model evaluation by at least 13% over the other schemes evaluated, although summertime deposition estimates were still biased by −31.4% against observations. The use of the DCA reduction mechanism physically links Hg2+ reduction to plausible atmospheric processes relevant under typical ambient conditions. |
| first_indexed | 2024-12-11T10:49:26Z |
| format | Article |
| id | doaj.art-a3bedb208a594ea9a5c277f0beb3b5da |
| institution | Directory Open Access Journal |
| issn | 2073-4433 |
| language | English |
| last_indexed | 2024-12-11T10:49:26Z |
| publishDate | 2013-12-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Atmosphere |
| spelling | doaj.art-a3bedb208a594ea9a5c277f0beb3b5da2022-12-22T01:10:22ZengMDPI AGAtmosphere2073-44332013-12-015111510.3390/atmos5010001atmos5010001Regional Air Quality Model Application of the Aqueous-Phase Photo Reduction of Atmospheric Oxidized Mercury by Dicarboxylic AcidsJesse O. Bash0Annmarie G. Carlton1William T. Hutzell2O. Russell Bullock Jr.3National Exposure Research Laboratory, US Environmental Protection Agency, Research Triangle Park, NC 27711, USADepartment of Environmental Sciences, Rutgers University, New Brunswick, NJ 08903, USANational Exposure Research Laboratory, US Environmental Protection Agency, Research Triangle Park, NC 27711, USANational Exposure Research Laboratory, US Environmental Protection Agency, Research Triangle Park, NC 27711, USAIn most ecosystems, atmospheric deposition is the primary input of mercury. The total wet deposition of mercury in atmospheric chemistry models is sensitive to parameterization of the aqueous-phase reduction of divalent oxidized mercury (Hg2+). However, most atmospheric chemistry models use a parameterization of the aqueous-phase reduction of Hg2+ that has been shown to be unlikely under normal ambient conditions or use a non mechanistic value derived to optimize wet deposition results. Recent laboratory experiments have shown that Hg2+ can be photochemically reduced to elemental mercury (Hg) in the aqueous-phase by dissolved organic matter and a mechanism and the rate for Hg2+ photochemical reduction by dicarboxylic acids (DCA) has been proposed. For the first time in a regional scale model, the DCA mechanism has been applied. The HO2-Hg2+ reduction mechanism, the proposed DCA reduction mechanism, and no aqueous-phase reduction (NAR) of Hg2+ are evaluated against weekly wet deposition totals, concentrations and precipitation observations from the Mercury Deposition Network (MDN) using the Community Multiscale Air Quality (CMAQ) model version 4.7.1. Regional scale simulations of mercury wet deposition using a DCA reduction mechanism evaluated well against observations, and reduced the bias in model evaluation by at least 13% over the other schemes evaluated, although summertime deposition estimates were still biased by −31.4% against observations. The use of the DCA reduction mechanism physically links Hg2+ reduction to plausible atmospheric processes relevant under typical ambient conditions.http://www.mdpi.com/2073-4433/5/1/1mercury depositionatmospheric mercury |
| spellingShingle | Jesse O. Bash Annmarie G. Carlton William T. Hutzell O. Russell Bullock Jr. Regional Air Quality Model Application of the Aqueous-Phase Photo Reduction of Atmospheric Oxidized Mercury by Dicarboxylic Acids Atmosphere mercury deposition atmospheric mercury |
| title | Regional Air Quality Model Application of the Aqueous-Phase Photo Reduction of Atmospheric Oxidized Mercury by Dicarboxylic Acids |
| title_full | Regional Air Quality Model Application of the Aqueous-Phase Photo Reduction of Atmospheric Oxidized Mercury by Dicarboxylic Acids |
| title_fullStr | Regional Air Quality Model Application of the Aqueous-Phase Photo Reduction of Atmospheric Oxidized Mercury by Dicarboxylic Acids |
| title_full_unstemmed | Regional Air Quality Model Application of the Aqueous-Phase Photo Reduction of Atmospheric Oxidized Mercury by Dicarboxylic Acids |
| title_short | Regional Air Quality Model Application of the Aqueous-Phase Photo Reduction of Atmospheric Oxidized Mercury by Dicarboxylic Acids |
| title_sort | regional air quality model application of the aqueous phase photo reduction of atmospheric oxidized mercury by dicarboxylic acids |
| topic | mercury deposition atmospheric mercury |
| url | http://www.mdpi.com/2073-4433/5/1/1 |
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