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Hewa Edirappulige DT, Kirby IJ, Beckett CK, Dibble TS. Atmospheric Chemistry of HOHg (II)O • Mimics That of a Hydroxyl Radical. J Phys Chem A 2023; 127:8392-8403. [PMID: 37769282 DOI: 10.1021/acs.jpca.3c04159] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/30/2023]
Abstract
HOHg(II)O•, formed from HOHg(I)• + O3, is a key intermediate in the OH-initiated oxidation of Hg(0) in the atmosphere. As no experimental data are available for HOHg(II)O•, we use computational chemistry (CCSD(T)//M06-2X/AVTZ) to characterize its reactions with atmospheric trace gases (NO, NO2, CH4, C2H4, CH2O and CO). In summary, HOHg(II)O•, like the analogous BrHg(II)O• radical, largely mimics the reactivity of •OH in reactions with NOx, alkanes, alkenes, and aldehydes. The rate constant for its reaction with methane (HOHg(II)O• + CH4 → Hg(II)(OH)2 + •CH3) is about four times higher than that of •OH at 298 K. All of these reactions maintain mercury as Hg(II), except for HOHg(II)O• + CO → HOHg(I)• + CO2. Considering only the six reactions studied here, we find that reduction by CO dominates the fate of HOHg(II)O• (79-93%) in many air masses (in the stratosphere and at ground level in rural, marine, and polluted urban regions) with only modest competition from HOHg(II)O• + CH4 (<15%). We expect that this work will help global modeling of atmospheric mercury chemistry.
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Affiliation(s)
- Darshi T Hewa Edirappulige
- Department of Chemistry, State University of New York, College of Environmental Science and Forestry, 1 Forestry Drive, Syracuse, New York 13210, United States
| | - Ilena J Kirby
- Department of Chemistry, State University of New York, College of Environmental Science and Forestry, 1 Forestry Drive, Syracuse, New York 13210, United States
| | - Camille K Beckett
- Department of Chemistry, State University of New York, College of Environmental Science and Forestry, 1 Forestry Drive, Syracuse, New York 13210, United States
| | - Theodore S Dibble
- Department of Chemistry, State University of New York, College of Environmental Science and Forestry, 1 Forestry Drive, Syracuse, New York 13210, United States
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Li T, Mao H, Wang Z, Yu JZ, Li S, Nie X, Herrmann H, Wang Y. Field Evidence for Asian Outflow and Fast Depletion of Total Gaseous Mercury in the Polluted Coastal Atmosphere. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:4101-4112. [PMID: 36847858 DOI: 10.1021/acs.est.2c07551] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Atmospheric mercury (Hg) cycling in polluted coastal atmosphere is complicated and not fully understood. Here, we present measurements of total gaseous mercury (TGM) monitored at a coastal mountaintop in Hong Kong downwind of mainland China. Sharp TGM peaks during cold front passages were frequently observed due to Asian pollution outflow with typical TGM/CO slopes of 6.8 ± 2.2 pg m-3 ppbv-1. Contrary to the daytime maximums of other air pollutants, TGM exhibited a distinct diurnal variation with a midday minimum. Moreover, we observed four cases of extremely fast TGM depletion after sunrise, during which TGM concentrations rapidly dipped to 0.3-0.6 ng m-3 accompanied by other pollutants on the rise. Simulated meteorological fields revealed that morning upslope flow transporting anthropogenically polluted but TGM-depleted air masses from the mixed layer caused morning TGM depletion at the mountaintop location. The TGM-depleted air masses were hypothesized to result mainly from fast photooxidation of Hg after sunrise with minor contributions from dry deposition (5.0%) and nocturnal oxidation (0.6%). A bromine-induced two-step oxidation mechanism involving abundant pollutants (NO2, O3, etc.) was estimated to play a dominant role, contributing 55%-60% of depleted TGM and requiring 0.20-0.26 pptv Br, an amount potentially available through sea salt aerosol debromination. Our findings suggest significant effects of the interaction between anthropogenic pollution and marine halogen chemistry on atmospheric Hg cycling in the coastal areas.
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Affiliation(s)
- Tao Li
- School of Environmental Science and Engineering, Shandong Key Laboratory of Environmental Processes and Health, Shandong University, Qingdao 266237, China
| | - Huiting Mao
- Department of Chemistry, College of Environmental Science and Forestry, State University of New York, Syracuse, New York 13210, United States
| | - Zhe Wang
- Division of Environment and Sustainability, Hong Kong University of Science and Technology, Kowloon, Hong Kong 999077, China
| | - Jian Zhen Yu
- Division of Environment and Sustainability, Hong Kong University of Science and Technology, Kowloon, Hong Kong 999077, China
| | - Shuwen Li
- Laboratory of Cloud-Precipitation Physics and Severe Storms (LACS), Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China
| | - Xiaoling Nie
- School of Environmental Science and Engineering, Shandong Key Laboratory of Environmental Processes and Health, Shandong University, Qingdao 266237, China
| | - Hartmut Herrmann
- School of Environmental Science and Engineering, Shandong Key Laboratory of Environmental Processes and Health, Shandong University, Qingdao 266237, China
- Atmospheric Chemistry Department (ACD), Leibniz Institute for Tropospheric Research (TROPOS), D-04318 Leipzig, Germany
| | - Yan Wang
- School of Environmental Science and Engineering, Shandong Key Laboratory of Environmental Processes and Health, Shandong University, Qingdao 266237, China
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Gómez Martín JC, Lewis TR, Douglas KM, Blitz MA, Saiz-Lopez A, Plane JMC. The reaction between HgBr and O 3: kinetic study and atmospheric implications. Phys Chem Chem Phys 2022; 24:12419-12432. [PMID: 35575018 PMCID: PMC9131727 DOI: 10.1039/d2cp00754a] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The rate constants of many reactions currently considered to be important in the atmospheric chemistry of mercury remain to be measured in the laboratory. Here we report the first experimental determination of the rate constant of the gas-phase reaction between the HgBr radical and ozone, for which a value at room temperature of k(HgBr + O3) = (7.5 ± 0.6) × 10-11 cm3 molecule s-1 (1σ) has been obtained. The rate constants of two reduction side reactions were concurrently determined: k(HgBr + O) = (5.3 ± 0.4) × 10-11 cm3 molecule s-1 and k(HgBrO + O) = (9.1 ± 0.6) × 10-11 cm3 molecule s-1. The value of k(HgBr + O3) is slightly lower than the collision number, confirming the absence of a significant energy barrier. Considering the abundance of ozone in the troposphere, our experimental rate constant supports recent modelling results suggesting that the main atmospheric fate of HgBr is reaction with ozone to form BrHgO.
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Affiliation(s)
| | - Thomas R Lewis
- Department of Atmospheric Chemistry and Climate, Institute of Physical Chemistry Rocasolano, CSIC, Serrano 119, 28006 Madrid, Spain. .,School of Chemistry, University of Leeds, LS2 9JT Leeds, UK
| | | | - Mark A Blitz
- School of Chemistry, University of Leeds, LS2 9JT Leeds, UK
| | - Alfonso Saiz-Lopez
- Department of Atmospheric Chemistry and Climate, Institute of Physical Chemistry Rocasolano, CSIC, Serrano 119, 28006 Madrid, Spain.
| | - John M C Plane
- School of Chemistry, University of Leeds, LS2 9JT Leeds, UK
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4
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Shah V, Jacob DJ, Thackray CP, Wang X, Sunderland EM, Dibble TS, Saiz-Lopez A, Černušák I, Kellö V, Castro PJ, Wu R, Wang C. Improved Mechanistic Model of the Atmospheric Redox Chemistry of Mercury. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:14445-14456. [PMID: 34724789 DOI: 10.1021/acs.est.1c03160] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
We present a new chemical mechanism for Hg0/HgI/HgII atmospheric cycling, including recent laboratory and computational data, and implement it in the GEOS-Chem global atmospheric chemistry model for comparison to observations. Our mechanism includes the oxidation of Hg0 by Br and OH, subsequent oxidation of HgI by ozone and radicals, respeciation of HgII in aerosols and cloud droplets, and speciated HgII photolysis in the gas and aqueous phases. The tropospheric Hg lifetime against deposition in the model is 5.5 months, consistent with observational constraints. The model reproduces the observed global surface Hg0 concentrations and HgII wet deposition fluxes. Br and OH make comparable contributions to global net oxidation of Hg0 to HgII. Ozone is the principal HgI oxidant, enabling the efficient oxidation of Hg0 to HgII by OH. BrHgIIOH and HgII(OH)2, the initial HgII products of Hg0 oxidation, respeciate in aerosols and clouds to organic and inorganic complexes, and volatilize to photostable forms. Reduction of HgII to Hg0 takes place largely through photolysis of aqueous HgII-organic complexes. 71% of model HgII deposition is to the oceans. Major uncertainties for atmospheric Hg chemistry modeling include Br concentrations, stability and reactions of HgI, and speciation and photoreduction of HgII in aerosols and clouds.
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Affiliation(s)
- Viral Shah
- Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, United States
| | - Daniel J Jacob
- Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, United States
- Department of Earth and Planetary Sciences, Harvard University, Cambridge, Massachusetts 02138, United States
| | - Colin P Thackray
- Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, United States
| | - Xuan Wang
- School of Energy and Environment, City University of Hong Kong, Hong Kong SAR, China
| | - Elsie M Sunderland
- Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, United States
- Department of Environmental Health, Harvard T.H. Chan School of Public Health, Harvard University, Boston, Massachusetts 02115, United States
| | - Theodore S Dibble
- Department of Chemistry, State University of New York, College of Environmental Science and Forestry, Syracuse, New York 13210, United States
| | - Alfonso Saiz-Lopez
- Department of Atmospheric Chemistry and Climate, Institute of Physical Chemistry Rocasolano, CSIC, Madrid 28006, Spain
| | - Ivan Černušák
- Department of Physical and Theoretical Chemistry, Faculty of Natural Sciences, Comenius University in Bratislava, Ilkovičova 6, 84215 Bratislava, Slovakia
| | - Vladimir Kellö
- Department of Physical and Theoretical Chemistry, Faculty of Natural Sciences, Comenius University in Bratislava, Ilkovičova 6, 84215 Bratislava, Slovakia
| | - Pedro J Castro
- Department of Chemistry, State University of New York, College of Environmental Science and Forestry, Syracuse, New York 13210, United States
| | - Rongrong Wu
- Department of Physics and Astronomy, Mississippi State University, Starkville, Mississippi 39759, United States
| | - Chuji Wang
- Department of Physics and Astronomy, Mississippi State University, Starkville, Mississippi 39759, United States
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Francés‐Monerris A, Carmona‐García J, Acuña AU, Dávalos JZ, Cuevas CA, Kinnison DE, Francisco JS, Saiz‐Lopez A, Roca‐Sanjuán D. Photodissociation Mechanisms of Major Mercury(II) Species in the Atmospheric Chemical Cycle of Mercury. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.201915656] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- Antonio Francés‐Monerris
- Université de LorraineCNRS, LPCT 54000 Nancy France
- Departamento de Química FísicaUniversitat de València 46100 Burjassot Spain
| | | | - A. Ulises Acuña
- Department of Atmospheric Chemistry and ClimateInstitute of Physical Chemistry RocasolanoCSIC 28006 Madrid Spain
| | - Juan Z. Dávalos
- Department of Atmospheric Chemistry and ClimateInstitute of Physical Chemistry RocasolanoCSIC 28006 Madrid Spain
| | - Carlos A. Cuevas
- Department of Atmospheric Chemistry and ClimateInstitute of Physical Chemistry RocasolanoCSIC 28006 Madrid Spain
| | | | - Joseph S. Francisco
- Department of Earth and Environmental Sciences and Department of ChemistryUniversity of Pennsylvania Philadelphia PA 19104 USA
| | - Alfonso Saiz‐Lopez
- Department of Atmospheric Chemistry and ClimateInstitute of Physical Chemistry RocasolanoCSIC 28006 Madrid Spain
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Francés‐Monerris A, Carmona‐García J, Acuña AU, Dávalos JZ, Cuevas CA, Kinnison DE, Francisco JS, Saiz‐Lopez A, Roca‐Sanjuán D. Photodissociation Mechanisms of Major Mercury(II) Species in the Atmospheric Chemical Cycle of Mercury. Angew Chem Int Ed Engl 2020; 59:7605-7610. [DOI: 10.1002/anie.201915656] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2019] [Indexed: 12/23/2022]
Affiliation(s)
- Antonio Francés‐Monerris
- Université de LorraineCNRS, LPCT 54000 Nancy France
- Departamento de Química FísicaUniversitat de València 46100 Burjassot Spain
| | | | - A. Ulises Acuña
- Department of Atmospheric Chemistry and ClimateInstitute of Physical Chemistry RocasolanoCSIC 28006 Madrid Spain
| | - Juan Z. Dávalos
- Department of Atmospheric Chemistry and ClimateInstitute of Physical Chemistry RocasolanoCSIC 28006 Madrid Spain
| | - Carlos A. Cuevas
- Department of Atmospheric Chemistry and ClimateInstitute of Physical Chemistry RocasolanoCSIC 28006 Madrid Spain
| | | | - Joseph S. Francisco
- Department of Earth and Environmental Sciences and Department of ChemistryUniversity of Pennsylvania Philadelphia PA 19104 USA
| | - Alfonso Saiz‐Lopez
- Department of Atmospheric Chemistry and ClimateInstitute of Physical Chemistry RocasolanoCSIC 28006 Madrid Spain
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