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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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2
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Zhang Y, Zhao M, Liu Y, Sun Y. The influence of a single water molecule on the reaction of BrO + HONO. J Mol Graph Model 2022; 116:108261. [PMID: 35926333 DOI: 10.1016/j.jmgm.2022.108261] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Revised: 06/02/2022] [Accepted: 06/23/2022] [Indexed: 12/15/2022]
Abstract
Quantum chemical computations and transition state theory are employed to systematically research the influence of a single molecule water on the BrO + HONO reaction. Two distinct reactions, namely BrO + trans-HONO and BrO + cis-HONO are explored for the reaction in the absence of water, which is mainly decided by the configuration of HONO. With introduction a single water molecule to the reaction, the rate coefficient of the channel starting from BrO + cis-HONO and BrO + trans-HONO are 2.43 × 10-19 and 5.22 × 10-22 cm3 molecule-1 s-1, which is larger than the reaction in the absence of water. For further comprehend the impact of water on the BrO + HONO reaction, it is necessary to compute the effective rate coefficient by taking into account the concentration of water. The water-assisted effective rate coefficients for the BrO + HONO reaction are smaller than that the reaction in the absence of water. The reaction of BrO with cis-HONO is feasible both in absence and existence of water.
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Affiliation(s)
- Yunju Zhang
- Key Laboratory of Photoinduced Functional Materials, Mianyang Normal University, Mianyang, 621000, PR China; Beijing Key Laboratory of Flavor Chemistry, Beijing Technology and Business University (BTBU), 100048, Beijing, PR China.
| | - Meilian Zhao
- College of Medical Technology, Chengdu University of Traditional Chinese Medicine Liutai Avenue, Wenjiang District, Chengdu, PR China
| | - Yongguo Liu
- Beijing Key Laboratory of Flavor Chemistry, Beijing Technology and Business University (BTBU), 100048, Beijing, PR China
| | - Yuxi Sun
- Key Laboratory of Photoinduced Functional Materials, Mianyang Normal University, Mianyang, 621000, PR China
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3
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The influence of a single water molecule on the reaction of IO + HONO. Struct Chem 2022. [DOI: 10.1007/s11224-022-01972-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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4
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Priyadarshanee M, Chatterjee S, Rath S, Dash HR, Das S. Cellular and genetic mechanism of bacterial mercury resistance and their role in biogeochemistry and bioremediation. JOURNAL OF HAZARDOUS MATERIALS 2022; 423:126985. [PMID: 34464861 DOI: 10.1016/j.jhazmat.2021.126985] [Citation(s) in RCA: 34] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2021] [Revised: 08/17/2021] [Accepted: 08/19/2021] [Indexed: 06/13/2023]
Abstract
Mercury (Hg) is a highly toxic element that occurs at low concentrations in nature. However, various anthropogenic and natural sources contribute around 5000 to 8000 metric tons of Hg per year, rapidly deteriorating the environmental conditions. Mercury-resistant bacteria that possess the mer operon system have the potential for Hg bioremediation through volatilization from the contaminated milieus. Thus, bacterial mer operon plays a crucial role in Hg biogeochemistry and bioremediation by converting both reactive inorganic and organic forms of Hg to relatively inert, volatile, and monoatomic forms. Both the broad-spectrum and narrow-spectrum bacteria harbor many genes of mer operon with their unique definitive functions. The presence of mer genes or proteins can regulate the fate of Hg in the biogeochemical cycle in the environment. The efficiency of Hg transformation depends upon the nature and diversity of mer genes present in mercury-resistant bacteria. Additionally, the bacterial cellular mechanism of Hg resistance involves reduced Hg uptake, extracellular sequestration, and bioaccumulation. The presence of unique physiological properties in a specific group of mercury-resistant bacteria enhances their bioremediation capabilities. Many advanced biotechnological tools also can improve the bioremediation efficiency of mercury-resistant bacteria to achieve Hg bioremediation.
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Affiliation(s)
- Monika Priyadarshanee
- Laboratory of Environmental Microbiology and Ecology (LEnME), Department of Life Science, National Institute of Technology Rourkela, Rourkela 769 008, Odisha, India
| | - Shreosi Chatterjee
- Laboratory of Environmental Microbiology and Ecology (LEnME), Department of Life Science, National Institute of Technology Rourkela, Rourkela 769 008, Odisha, India
| | - Sonalin Rath
- Laboratory of Environmental Microbiology and Ecology (LEnME), Department of Life Science, National Institute of Technology Rourkela, Rourkela 769 008, Odisha, India
| | - Hirak R Dash
- Laboratory of Environmental Microbiology and Ecology (LEnME), Department of Life Science, National Institute of Technology Rourkela, Rourkela 769 008, Odisha, India
| | - Surajit Das
- Laboratory of Environmental Microbiology and Ecology (LEnME), Department of Life Science, National Institute of Technology Rourkela, Rourkela 769 008, Odisha, India.
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5
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Tang S, Du L. A single water molecule accelerating the atmospheric reaction of HONO with ClO. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2019; 26:27842-27853. [PMID: 31342353 DOI: 10.1007/s11356-019-05999-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Accepted: 07/16/2019] [Indexed: 06/10/2023]
Abstract
The role of a single water molecule on the atmospheric reaction of HONO + ClO is systematically investigated employing quantum chemical calculation combined with harmonic transition state theory. Two reaction pathways, cis-HONO + ClO and trans-HONO + ClO, are identified for the naked reaction, which depends on the configurations of HONO. When adding a single water molecule to this reaction, the rate constants of cis-HONO + ClO and trans-HONO + ClO pathways are 7.97 × 10-21 and 2.29 × 10-17 cm3 molecule-1 s-1, respectively, larger than the corresponding naked reaction. To further understand the role of water on the HONO + ClO reaction, it is necessary to calculate the effective rate constant by considering the concentration of water. It shows that the effective rate constants of water-assisted cis-HONO + ClO pathway are much smaller than those of the naked reaction, whereas the presence of water accelerates the trans-HONO + ClO at room temperature. This study demonstrates that water has a positive role in the pathway of trans-HONO + ClO by modifying the stabilities of reactant complexes and transition states through the hydrogen bond formation, which contributes to the sink of atmospheric HONO. In addition, the kinetic branching ratio indicates that the favorable reaction is the trans-HONO + ClO instead of the cis-HONO + ClO pathway, in contrast to the naked reaction. These results reveal the importance of water in the evaluation of the fate of active species in the atmosphere. Graphical Abstract.
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Affiliation(s)
- Shanshan Tang
- Environment Research Institute, Shandong University, Binhai Road 72, Qingdao, 266237, China
| | - Lin Du
- Environment Research Institute, Shandong University, Binhai Road 72, Qingdao, 266237, China.
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McNamara SM, W Raso AR, Wang S, Thanekar S, Boone EJ, Kolesar KR, Peterson PK, Simpson WR, Fuentes JD, Shepson PB, Pratt KA. Springtime Nitrogen Oxide-Influenced Chlorine Chemistry in the Coastal Arctic. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:8057-8067. [PMID: 31184868 DOI: 10.1021/acs.est.9b01797] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Atomic chlorine (Cl) is a strong atmospheric oxidant that shortens the lifetimes of pollutants and methane in the springtime Arctic, where the molecular halogens Cl2 and BrCl are known Cl precursors. Here, we quantify the contributions of reactive chlorine trace gases and present the first observations, to our knowledge, of ClNO2 (another Cl precursor), N2O5, and HO2NO2 in the Arctic. During March - May 2016 near Utqiaġvik, Alaska, up to 21 ppt of ClNO2, 154 ppt of Cl2, 27 ppt of ClO, 71 ppt of N2O5, 21 ppt of BrCl, and 153 ppt of HO2NO2 were measured using chemical ionization mass spectrometry. The main Cl precursor was calculated to be Cl2 (up to 73%) in March, while BrCl was a greater contributor (63%) in May, when total Cl production was lower. Elevated levels of ClNO2, N2O5, Cl2, and HO2NO2 coincided with pollution influence from the nearby town of Utqiaġvik and the North Slope of Alaska (Prudhoe Bay) Oilfields. We propose a coupled mechanism linking NOx with Arctic chlorine chemistry. Enhanced Cl2 was likely the result of the multiphase reaction of Cl-(aq) with ClONO2, formed from the reaction of ClO and NO2. In addition to this NOx-enhanced chlorine chemistry, Cl2 and BrCl were observed under clean Arctic conditions from snowpack photochemical production. These connections between NOx and chlorine chemistry, and the role of snowpack recycling, are important given increasing shipping and fossil fuel extraction predicted to accompany Arctic sea ice loss.
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Affiliation(s)
- Stephen M McNamara
- Department of Chemistry , University of Michigan , Ann Arbor , Michigan 48109 , United States
| | - Angela R W Raso
- Department of Chemistry , University of Michigan , Ann Arbor , Michigan 48109 , United States
- Department of Chemistry , Purdue University , West Lafayette , Indiana 47907 , United States
| | - Siyuan Wang
- Department of Chemistry , University of Michigan , Ann Arbor , Michigan 48109 , United States
| | - Sham Thanekar
- Department of Meteorology and Atmospheric Science , Pennsylvania State University , University Park , Pennsylvania 16801 , United States
| | - Eric J Boone
- Department of Chemistry , University of Michigan , Ann Arbor , Michigan 48109 , United States
- Department of Chemistry , Purdue University , West Lafayette , Indiana 47907 , United States
| | - Katheryn R Kolesar
- Department of Chemistry , University of Michigan , Ann Arbor , Michigan 48109 , United States
| | - Peter K Peterson
- Department of Chemistry , University of Michigan , Ann Arbor , Michigan 48109 , United States
| | - William R Simpson
- Department of Chemistry and Biochemistry , University of Alaska Fairbanks , Fairbanks , Alaska 99775 , United States
| | - Jose D Fuentes
- Department of Meteorology and Atmospheric Science , Pennsylvania State University , University Park , Pennsylvania 16801 , United States
| | - Paul B Shepson
- Department of Chemistry , Purdue University , West Lafayette , Indiana 47907 , United States
- Department of Earth, Atmospheric, and Planetary Sciences & Purdue Climate Change Research Center , Purdue University , West Lafayette , Indiana 47907 , United States
| | - Kerri A Pratt
- Department of Chemistry , University of Michigan , Ann Arbor , Michigan 48109 , United States
- Department of Earth and Environmental Sciences , University of Michigan , Ann Arbor , Michigan 48109 , United States
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Direct detection of atmospheric atomic bromine leading to mercury and ozone depletion. Proc Natl Acad Sci U S A 2019; 116:14479-14484. [PMID: 31253702 DOI: 10.1073/pnas.1900613116] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Bromine atoms play a central role in atmospheric reactive halogen chemistry, depleting ozone and elemental mercury, thereby enhancing deposition of toxic mercury, particularly in the Arctic near-surface troposphere. However, direct bromine atom measurements have been missing to date, due to the lack of analytical capability with sufficient sensitivity for ambient measurements. Here we present direct atmospheric bromine atom measurements, conducted in the springtime Arctic. Measured bromine atom levels reached 14 parts per trillion (ppt, pmol mol-1; 4.2 × 108 atoms per cm-3) and were up to 3-10 times higher than estimates using previous indirect measurements not considering the critical role of molecular bromine. Observed ozone and elemental mercury depletion rates are quantitatively explained by the measured bromine atoms, providing field validation of highly uncertain mercury chemistry. Following complete ozone depletion, elevated bromine concentrations are sustained by photochemical snowpack emissions of molecular bromine and nitrogen oxides, resulting in continued atmospheric mercury depletion. This study provides a breakthrough in quantitatively constraining bromine chemistry in the polar atmosphere, where this chemistry connects the rapidly changing surface to pollutant fate.
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8
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Abrahamsson K, Granfors A, Ahnoff M, Cuevas CA, Saiz-Lopez A. Organic bromine compounds produced in sea ice in Antarctic winter. Nat Commun 2018; 9:5291. [PMID: 30538229 PMCID: PMC6290016 DOI: 10.1038/s41467-018-07062-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Accepted: 10/08/2018] [Indexed: 11/09/2022] Open
Abstract
During polar springtime, active bromine drives ozone, a greenhouse gas, to near-zero levels. Bromine production and emission in the polar regions have so far been assumed to require sunlight. Here, we report measurements of bromocarbons in sea ice, snow, and air during the Antarctic winter that reveal an unexpected new source of organic bromine to the atmosphere during periods of no sunlight. The results show that Antarctic winter sea ice provides 10 times more bromocarbons to the atmosphere than Southern Ocean waters, and substantially more than summer sea ice. The inclusion of these measurements in a global climate model indicates that the emitted bromocarbons will disperse throughout the troposphere in the southern hemisphere and through photochemical degradation to bromine atoms, contribute ~ 10% to the tropospheric reactive bromine budget. Combined together, our results suggest that winter sea ice could potentially be an important source of atmospheric bromine with implications for atmospheric chemistry and climate at a hemispheric scale.
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Affiliation(s)
- Katarina Abrahamsson
- Department of Marine Sciences, University of Gothenburg, Carl Skottbergs gata 22B, SE-41319, Gothenburg, Sweden.
| | - Anna Granfors
- AstraZeneca, Product Technology and Development, SE-43183, Mölndal, Sweden
| | - Martin Ahnoff
- Department of Marine Sciences, University of Gothenburg, Carl Skottbergs gata 22B, SE-41319, Gothenburg, Sweden
| | - Carlos A Cuevas
- Department of Atmospheric Chemistry and Climate, Institute of Physical Chemistry Rocasolano, Serrano 119, 28006, Madrid, Spain
| | - Alfonso Saiz-Lopez
- Department of Atmospheric Chemistry and Climate, Institute of Physical Chemistry Rocasolano, Serrano 119, 28006, Madrid, Spain.
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Tang S, Tsona NT, Li J, Du L. Role of water on the H-abstraction from methanol by ClO. J Environ Sci (China) 2018; 71:89-98. [PMID: 30195693 DOI: 10.1016/j.jes.2017.12.023] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2017] [Revised: 12/28/2017] [Accepted: 12/28/2017] [Indexed: 06/08/2023]
Abstract
The influence of a single water molecule on the reaction mechanism and kinetics of hydrogen abstraction from methanol (CH3OH) by the ClO radical has been investigated using ab initio calculations. The reaction proceeds through two channels: abstraction of the hydroxyl H-atom and methyl H-atom of CH3OH by ClO, leading to the formation of CH3O+HOCl (+H2O) and CH2OH+HOCl (+H2O), respectively. In both cases, pre- and post-reactive complexes were located at the entrance and exit channel on the potential energy surfaces. Results indicate that the formation of CH2OH+HOCl (+H2O) is predominant over the formation of CH3O+HOCl (+H2O), with ambient rate constants of 3.07×10-19 and 3.01×10-23cm3/(molecule·sec), respectively, for the reaction without water. Over the temperature range 216.7-298.2K, the presence of water is seen to effectively lower the rate constants for the most favorable pathways by 4-6 orders of magnitude in both cases. It is therefore concluded that water plays an inhibitive role on the CH3OH+ClO reaction under tropospheric conditions.
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Affiliation(s)
- Shanshan Tang
- Environment Research Institute, Shandong University, Jinan 250100, China
| | - Narcisse T Tsona
- Environment Research Institute, Shandong University, Jinan 250100, China
| | - Junyao Li
- Environment Research Institute, Shandong University, Jinan 250100, China
| | - Lin Du
- Environment Research Institute, Shandong University, Jinan 250100, China.
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10
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Jiao Y, Dibble TS. Structures, Vibrational Frequencies, and Bond Energies of the BrHgOX and BrHgXO Species Formed in Atmospheric Mercury Depletion Events. J Phys Chem A 2017; 121:7976-7985. [DOI: 10.1021/acs.jpca.7b06829] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Yuge Jiao
- 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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11
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Custard KD, Pratt KA, Wang S, Shepson PB. Constraints on Arctic Atmospheric Chlorine Production through Measurements and Simulations of Cl 2 and ClO. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2016; 50:12394-12400. [PMID: 27768281 DOI: 10.1021/acs.est.6b03909] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
During springtime, unique halogen chemistry involving chlorine and bromine atoms controls the prevalence of volatile organic compounds, ozone, and mercury in the Arctic lower troposphere. In situ measurements of the chlorine monoxide radical, ClO, and its precursor, Cl2, along with BrO and Br2, were conducted using chemical ionization mass spectrometry (CIMS) during the Bromine, Ozone, and Mercury Experiment (BROMEX) near Barrow, Alaska, in March 2012. To our knowledge, these data represent the first ClO measurements made using CIMS. A maximum daytime ClO concentration of 28 ppt was observed following an early morning peak of 75 ppt of Cl2. A zero-dimensional photochemistry model was constrained to Cl2 observations and used to simulate ClO during a 7-day period of the field campaign. The model simulates ClO within the measurement uncertainty, and the model results highlight the importance of chlorine chemistry participation in bromine radical cycling, as well as the dependence of halogen chemistry on NOx levels. The ClO measurements and simulations are consistent with Cl2 being the dominant Cl atom source in the Arctic boundary layer. Simulated Cl atom concentrations, up to ∼1 × 106 molecules cm-3, highlight the importance of chlorine chemistry in the degradation of volatile organic compounds, including the greenhouse gas methane.
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Affiliation(s)
- Kyle D Custard
- Department of Chemistry, Purdue University , West Lafayette, Indiana 47907, United States
| | - Kerri A Pratt
- Department of Chemistry, Purdue University , West Lafayette, Indiana 47907, United States
- Department of Chemistry, University of Michigan , Ann Arbor, Michigan 48109, United States
- Department of Earth & Environmental Sciences, University of Michigan , Ann Arbor, Michigan 48109, United States
| | - Siyuan Wang
- Department of Chemistry, University of Michigan , Ann Arbor, Michigan 48109, United States
| | - Paul B Shepson
- Department of Chemistry, Purdue University , West Lafayette, Indiana 47907, United States
- Department of Earth, Atmospheric, and Planetary Sciences and Purdue Climate Change Research Center, Purdue University , West Lafayette, Indiana 47907, United States
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12
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Sun G, Sommar J, Feng X, Lin CJ, Ge M, Wang W, Yin R, Fu X, Shang L. Mass-Dependent and -Independent Fractionation of Mercury Isotope during Gas-Phase Oxidation of Elemental Mercury Vapor by Atomic Cl and Br. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2016; 50:9232-41. [PMID: 27501307 DOI: 10.1021/acs.est.6b01668] [Citation(s) in RCA: 71] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
This study presents the first measurement of Hg stable isotope fractionation during gas-phase oxidation of Hg(0) vapor by halogen atoms (Cl(•), Br(•)) in the laboratory at 750 ± 1 Torr and 298 ± 3 K. Using a relative rate technique, the rate coefficients for Hg(0)+Cl(•) and Hg(0)+Br(•) reactions are determined to be (1.8 ± 0.5) × 10(-11) and (1.6 ± 0.8) × 10(-12) cm(3) molecule(-1) s(-1), respectively. Results show that heavier isotopes are preferentially enriched in the remaining Hg(0) during Cl(•) initiated oxidation, whereas being enriched in the product during oxidation by Br(•). The fractionation factors for (202)Hg/(198)Hg during the Cl(•) and Br(•) initiated oxidations are α(202/198) = 0.99941 ± 0.00006 (2σ) and 1.00074 ± 0.00014 (2σ), respectively. A Δ(199)Hg/Δ(201)Hg ratio of 1.64 ± 0.30 (2σ) during oxidation of Hg(0) by Br atoms suggests that Hg-MIF is introduced by the nuclear volume effect (NVE). In contrast, the Hg(0) + Cl(•) reaction produces a Δ(199)Hg/Δ(201)Hg-slope of 1.89 ± 0.18 (2σ), which in addition to a high degree of odd-mass-number isotope MIF suggests impacts from MIF effects other than NVE. This reaction also exhibits significant MIF of (200)Hg (Δ(200)Hg, up to -0.17‰ in the reactant) and is the first physicochemical process identified to trigger (200)Hg anomalies that are frequently detected in atmospheric samples.
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Affiliation(s)
- Guangyi Sun
- University of Chinese Academy of Sciences, Beijing 100190, China
| | | | | | - Che-Jen Lin
- Center for Advances in Water and Air Quality, Lamar University , Beaumont, Texas 77710, United States
| | - Maofa Ge
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190, China
| | - Weigang Wang
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190, China
| | - Runsheng Yin
- Environmental Chemistry and Technology Program, University of Wisconsin-Madison , Madison, Wisconsin 53706, United States
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Gladich I, Francisco JS, Buszek RJ, Vazdar M, Carignano MA, Shepson PB. Ab initio study of the reaction of ozone with bromide ion. J Phys Chem A 2015; 119:4482-8. [PMID: 25642913 DOI: 10.1021/jp5101279] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Surface level ozone destruction in polar environments may be initiated by oxidation of bromide ions by ozone, ultimately leading to Br2 production. Ab initio calculations are used to support the development of atmospheric chemistry models, but errors can occur in study of the bromide-ozone reaction due to inappropriate treatment of the many-electron species and the ionic nature of the reaction. In this work, a high level ab initio study is used to take into account the electronic correlation and the polarization effects. Our results show three possible pathways for the reaction. In particular, we find that this process, though endothermic on the singlet spin state surface, can be energetically feasible on the triplet surface. The triplet surface can be reached through photoexcitation of ozone or by the spin crossing of the potential energy surface. Because this process is known to occur in the dark, it may be that it occurs after intersystem crossing to a triplet surface. This paper also provides a starting point calibration for any future ab initio calculation studies of the bromide-ozone reaction, from the gas to the condensed phase.
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Affiliation(s)
- Ivan Gladich
- †International School For Advanced Studies (SISSA), Trieste I-34136, Italy
| | | | | | - Mario Vazdar
- ∥Division of Organic Chemistry and Biochemistry, Rudjer Boskovic Institute, P.O.B. 180, HR-10002 Zagreb, Croatia
| | - Marcelo A Carignano
- ⊥Qatar Environment and Energy Research Institute, P.O. Box 5825, Doha, Qatar
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Steffen A, Lehnherr I, Cole A, Ariya P, Dastoor A, Durnford D, Kirk J, Pilote M. Atmospheric mercury in the Canadian Arctic. Part I: a review of recent field measurements. THE SCIENCE OF THE TOTAL ENVIRONMENT 2015; 509-510:3-15. [PMID: 25497576 DOI: 10.1016/j.scitotenv.2014.10.109] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2014] [Revised: 10/27/2014] [Accepted: 10/31/2014] [Indexed: 06/04/2023]
Abstract
Long-range atmospheric transport and deposition are important sources of mercury (Hg) to Arctic aquatic and terrestrial ecosystems. We review here recent progress made in the study of the transport, transformation, deposition and reemission of atmospheric Hg in the Canadian Arctic, focusing on field measurements (see Dastoor et al., this issue for a review of modeling studies on the same topics). Redox processes control the speciation of atmospheric Hg, and thus impart an important influence on Hg deposition, particularly during atmospheric mercury depletion events (AMDEs). Bromine radicals were identified as the primary oxidant of atmospheric Hg during AMDEs. Since the start of monitoring at Alert (NU) in 1995, the timing of peak AMDE occurrence has shifted to earlier times in the spring (from May to April) in recent years, and while AMDE frequency and GEM concentrations are correlated with local meteorological conditions, the reasons for this timing-shift are not understood. Mercury is subject to various post-depositional processes in snowpacks and a large portion of deposited oxidized Hg can be reemitted following photoreduction; how much Hg is deposited and reemitted depends on geographical location, meteorological, vegetative and sea-ice conditions, as well as snow chemistry. Halide anions in the snow can stabilize Hg, therefore it is expected that a smaller fraction of deposited Hg will be reemitted from coastal snowpacks. Atmospheric gaseous Hg concentrations have decreased in some parts of the Arctic (e.g., Alert) from 2000 to 2009 but at a rate that was less than that at lower latitudes. Despite numerous recent advances, a number of knowledge gaps remain, including uncertainties in the identification of oxidized Hg species in the air (and how this relates to dry vs. wet deposition), physical-chemical processes in air, snow and water-especially over sea ice-and the relationship between these processes and climate change.
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Affiliation(s)
- Alexandra Steffen
- Environment Canada, Air Quality Processes Research, Toronto M3H 5T4, Ontario, Canada.
| | - Igor Lehnherr
- University of Waterloo, Department of Earth and Environmental Sciences, Waterloo N2L 3G1, Ontario, Canada
| | - Amanda Cole
- Environment Canada, Air Quality Processes Research, Toronto M3H 5T4, Ontario, Canada
| | - Parisa Ariya
- McGill University, Department of Chemistry, 801 Sherbrooke St. W., Montreal H3A 2K6, Quebec, Canada; McGill University, Department of Atmospheric and Oceanic Sciences, 801 Sherbrooke St. W., Montreal H3A 2K6, Quebec, Canada
| | - Ashu Dastoor
- Environment Canada, National Prediction Development Division, Dorval H9P 1J3, Quebec, Canada
| | - Dorothy Durnford
- Environment Canada, National Prediction Development Division, Dorval H9P 1J3, Quebec, Canada
| | - Jane Kirk
- Environment Canada, Aquatic Contaminants Research Division, Burlington L7R 4A6, Ontario, Canada
| | - Martin Pilote
- Environment Canada, Aquatic Contaminants Research Division, Montreal H2Y 2E7, Quebec, Canada
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Simpson WR, Brown SS, Saiz-Lopez A, Thornton JA, Glasow RV. Tropospheric halogen chemistry: sources, cycling, and impacts. Chem Rev 2015; 115:4035-62. [PMID: 25763598 PMCID: PMC4469175 DOI: 10.1021/cr5006638] [Citation(s) in RCA: 144] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- William R Simpson
- †Department of Chemistry and Biochemistry and Geophysical Institute, University of Alaska Fairbanks, Fairbanks, Alaska 99775, United States
| | - Steven S Brown
- ‡NOAA ESRL Chemical Sciences Division, Boulder, Colorado 80305-3337, United States
| | - Alfonso Saiz-Lopez
- ¶Atmospheric Chemistry and Climate Group, Institute of Physical Chemistry Rocasolano, CSIC, 28006 Madrid, Spain
| | - Joel A Thornton
- §Department of Atmospheric Sciences, University of Washington, Seattle, Washington 98195-1640, United States
| | - Roland von Glasow
- ∥Centre for Ocean and Atmospheric Sciences, School of Environmental Sciences, University of East Anglia, Norwich, Norfolk NR4 7TJ, U.K
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Moore CW, Obrist D, Steffen A, Staebler RM, Douglas TA, Richter A, Nghiem SV. Convective forcing of mercury and ozone in the Arctic boundary layer induced by leads in sea ice. Nature 2014; 506:81-4. [DOI: 10.1038/nature12924] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2013] [Accepted: 11/29/2013] [Indexed: 11/09/2022]
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Finley BD, Jaffe DA, Call K, Lyman S, Gustin MS, Peterson C, Miller M, Lyman T. Development, testing, and deployment of an air sampling manifold for spiking elemental and oxidized mercury during the Reno Atmospheric Mercury Intercomparison Experiment (RAMIX). ENVIRONMENTAL SCIENCE & TECHNOLOGY 2013; 47:7277-7284. [PMID: 23441676 DOI: 10.1021/es304185a] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The Reno Atmospheric Mercury Intercomparison Experiment (RAMIX) was in Reno, NV from August 22, 2011 to September 16, 2011. The goals of the experiment were to compare existing and new methods for measurements of ambient elemental and oxidized Hg, and to test these with quantitative spikes of Hg(0), HgBr2, O3 and water vapor. In this paper we describe the design, testing, and deployment of a high flow manifold system designed to deliver ambient air and spiked compounds to multiple instruments simultaneously. The manifold was constructed of 1" OD PFA tubing and heated to 115 °C for the entire active zone. Manifold flow was controlled at ∼200 LPM using a blower and a velocity sensor in a feedback control system. Permeation tubes in controlled ovens were used to deliver Hg(0) and HgBr2. Ozone was generated from a small UV lamp in a flow of high purity O2. Water vapor was generated by pumping a flow of purified N2 through heated, high purity water. The spiking delivery for Hg(0), HgBr2, O3, and water vapor after dilution in the manifold ranged up to 20 ng m(-3), 0.64 ng m(-3), 100 ppbv, and 20 g kg(-1), respectively. During laboratory tests the average transmission efficiencies for Hg(0), HgBr2, and O3 were found to be 92%, 76%, and 93%, respectively.
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Affiliation(s)
- B D Finley
- Department of Science and Technology, University of Washington-Bothell, 18115 Campus Way NE, Bothell, Washington 98011, United States.
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Ambrose JL, Lyman SN, Huang J, Gustin MS, Jaffe DA. Fast time resolution oxidized mercury measurements during the Reno Atmospheric Mercury Intercomparison Experiment (RAMIX). ENVIRONMENTAL SCIENCE & TECHNOLOGY 2013; 47:7285-7294. [PMID: 23425102 DOI: 10.1021/es303916v] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The Reno Atmospheric Mercury Intercomparison Experiment (RAMIX) was carried out from 22 August to 16 September, 2011 in Reno, NV to evaluate the performance of new and existing methods to measure atmospheric mercury (Hg). Measurements were made using a common sampling manifold to which controlled concentrations of Hg species, including gaseous elemental mercury (GEM) and HgBr2 (a surrogate gaseous oxidized mercury (GOM) compound), and potential interferents were added. We present an analysis of Hg measurements made using the University of Washington's Detector for Oxidized Hg Species (DOHGS), focusing on tests of GEM and HgBr2 spike recovery, the potential for interference from ozone (O3) and water vapor (WV), and temporal variability of ambient reactive mercury (RM). The mean GEM and HgBr2 spike recoveries measured with the DOHGS were 95% and 66%, respectively. The DOHGS responded linearly to HgBr2. We found no evidence that elevated O3 interfered in the DOHGS RM measurements. A reduction in RM collection and retention efficiencies at very high ambient WV mixing ratios is possible. Comparisons between the DOHGS and participating Hg instruments demonstrate good agreement for GEM and large discrepancies for RM. The results suggest that existing GOM measurements are biased low.
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Affiliation(s)
- Jesse L Ambrose
- Science and Technology Program, University of Washington-Bothell, Bothell, Washington 98011, United States.
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Nghiem SV, Rigor IG, Richter A, Burrows JP, Shepson PB, Bottenheim J, Barber DG, Steffen A, Latonas J, Wang F, Stern G, Clemente-Colón P, Martin S, Hall DK, Kaleschke L, Tackett P, Neumann G, Asplin MG. Field and satellite observations of the formation and distribution of Arctic atmospheric bromine above a rejuvenated sea ice cover. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/2011jd016268] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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