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Pan LL, Atlas EL, Honomichl SB, Smith WP, Kinnison DE, Solomon S, Santee ML, Saiz-Lopez A, Laube JC, Wang B, Ueyama R, Bresch JF, Hornbrook RS, Apel EC, Hills AJ, Treadaway V, Smith K, Schauffler S, Donnelly S, Hendershot R, Lueb R, Campos T, Viciani S, D’Amato F, Bianchini G, Barucci M, Podolske JR, Iraci LT, Gurganus C, Bui P, Dean-Day JM, Millán L, Ryoo JM, Barletta B, Koo JH, Kim J, Liang Q, Randel WJ, Thornberry T, Newman PA. East Asian summer monsoon delivers large abundances of very-short-lived organic chlorine substances to the lower stratosphere. Proc Natl Acad Sci U S A 2024; 121:e2318716121. [PMID: 38483991 PMCID: PMC10962947 DOI: 10.1073/pnas.2318716121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2023] [Accepted: 02/12/2024] [Indexed: 03/27/2024] Open
Abstract
Deep convection in the Asian summer monsoon is a significant transport process for lifting pollutants from the planetary boundary layer to the tropopause level. This process enables efficient injection into the stratosphere of reactive species such as chlorinated very-short-lived substances (Cl-VSLSs) that deplete ozone. Past studies of convective transport associated with the Asian summer monsoon have focused mostly on the south Asian summer monsoon. Airborne observations reported in this work identify the East Asian summer monsoon convection as an effective transport pathway that carried record-breaking levels of ozone-depleting Cl-VSLSs (mean organic chlorine from these VSLSs ~500 ppt) to the base of the stratosphere. These unique observations show total organic chlorine from VSLSs in the lower stratosphere over the Asian monsoon tropopause to be more than twice that previously reported over the tropical tropopause. Considering the recently observed increase in Cl-VSLS emissions and the ongoing strengthening of the East Asian summer monsoon under global warming, our results highlight that a reevaluation of the contribution of Cl-VSLS injection via the Asian monsoon to the total stratospheric chlorine budget is warranted.
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Affiliation(s)
- Laura L. Pan
- Atmospheric Chemistry Observations and Modeling Laboratory, NSF National Center for Atmospheric Research, Boulder, CO80301
| | - Elliot L. Atlas
- Rosenstiel School of Marine, Earth, and Atmospheric Science, Department of Atmospheric Sciences, University of Miami, Miami, FL33149
| | - Shawn B. Honomichl
- Atmospheric Chemistry Observations and Modeling Laboratory, NSF National Center for Atmospheric Research, Boulder, CO80301
| | - Warren P. Smith
- Atmospheric Chemistry Observations and Modeling Laboratory, NSF National Center for Atmospheric Research, Boulder, CO80301
| | - Douglas E. Kinnison
- Atmospheric Chemistry Observations and Modeling Laboratory, NSF National Center for Atmospheric Research, Boulder, CO80301
| | - Susan Solomon
- Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA02139
| | - Michelle L. Santee
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA91109
| | - Alfonso Saiz-Lopez
- Department of Atmospheric Chemistry and Climate, Institute of Physical Chemistry Blas Cabrera, The Spanish National Research Council (CSIC), Madrid28006, Spain
| | - Johannes C. Laube
- Institute for Energy and Climate Research (IEK-7), Forschungszentrum Jülich, Jülich52425, Germany
| | - Bin Wang
- Department of Atmospheric Sciences and International Pacific Research Center, The University of Hawaii, Honolulu, HI96822
| | - Rei Ueyama
- NASA Ames Research Center, Moffett Field, CA94035
| | - James F. Bresch
- Mesoscale and Microscale Meteorology Laboratory, NSF National Center for Atmospheric Research, Boulder, CO80301
| | - Rebecca S. Hornbrook
- Atmospheric Chemistry Observations and Modeling Laboratory, NSF National Center for Atmospheric Research, Boulder, CO80301
| | - Eric C. Apel
- Atmospheric Chemistry Observations and Modeling Laboratory, NSF National Center for Atmospheric Research, Boulder, CO80301
| | - Alan J. Hills
- Atmospheric Chemistry Observations and Modeling Laboratory, NSF National Center for Atmospheric Research, Boulder, CO80301
| | - Victoria Treadaway
- Rosenstiel School of Marine, Earth, and Atmospheric Science, Department of Atmospheric Sciences, University of Miami, Miami, FL33149
- Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, Boulder, CO80309
- National Oceanic and Atmospheric Administration Chemical Sciences Laboratory, Boulder, CO80305
| | - Katie Smith
- Rosenstiel School of Marine, Earth, and Atmospheric Science, Department of Atmospheric Sciences, University of Miami, Miami, FL33149
| | - Sue Schauffler
- Atmospheric Chemistry Observations and Modeling Laboratory, NSF National Center for Atmospheric Research, Boulder, CO80301
- Rosenstiel School of Marine, Earth, and Atmospheric Science, Department of Atmospheric Sciences, University of Miami, Miami, FL33149
| | - Stephen Donnelly
- Rosenstiel School of Marine, Earth, and Atmospheric Science, Department of Atmospheric Sciences, University of Miami, Miami, FL33149
- Department of Chemistry, Fort Hays State University, Hays, KS67601
| | - Roger Hendershot
- Atmospheric Chemistry Observations and Modeling Laboratory, NSF National Center for Atmospheric Research, Boulder, CO80301
- Rosenstiel School of Marine, Earth, and Atmospheric Science, Department of Atmospheric Sciences, University of Miami, Miami, FL33149
| | - Richard Lueb
- Atmospheric Chemistry Observations and Modeling Laboratory, NSF National Center for Atmospheric Research, Boulder, CO80301
- Rosenstiel School of Marine, Earth, and Atmospheric Science, Department of Atmospheric Sciences, University of Miami, Miami, FL33149
| | - Teresa Campos
- Atmospheric Chemistry Observations and Modeling Laboratory, NSF National Center for Atmospheric Research, Boulder, CO80301
| | - Silvia Viciani
- National Institute of Optics, National Research Council, Sesto Fiorentino50019, Italy
| | - Francesco D’Amato
- National Institute of Optics, National Research Council, Sesto Fiorentino50019, Italy
| | - Giovanni Bianchini
- National Institute of Optics, National Research Council, Sesto Fiorentino50019, Italy
| | - Marco Barucci
- National Institute of Optics, National Research Council, Sesto Fiorentino50019, Italy
| | | | | | - Colin Gurganus
- Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, Boulder, CO80309
- National Oceanic and Atmospheric Administration Chemical Sciences Laboratory, Boulder, CO80305
| | - Paul Bui
- NASA Ames Research Center, Moffett Field, CA94035
- Bay Area Environmental Research Institute, Moffett Field, CA94035
| | - Jonathan M. Dean-Day
- NASA Ames Research Center, Moffett Field, CA94035
- Bay Area Environmental Research Institute, Moffett Field, CA94035
| | - Luis Millán
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA91109
| | - Ju-Mee Ryoo
- NASA Ames Research Center, Moffett Field, CA94035
- Science and Technology Corporation, Moffett Field, CA94035
| | - Barbara Barletta
- Department of Chemistry, University of California Irvine, Irvine, CA92697
| | - Ja-Ho Koo
- Department of Atmospheric Sciences, Yonsei University, Seoul03722, Republic of Korea
| | - Joowan Kim
- Department of Atmospheric Science, Kongju National University, Gongju32588, Republic of Korea
| | - Qing Liang
- NASA Goddard Space Flight Center, Greenbelt, MD20771
| | - William J. Randel
- Atmospheric Chemistry Observations and Modeling Laboratory, NSF National Center for Atmospheric Research, Boulder, CO80301
| | - Troy Thornberry
- National Oceanic and Atmospheric Administration Chemical Sciences Laboratory, Boulder, CO80305
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2
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Charfeddine F, Zanchet A, Yazidi O, Cuevas CA, Saiz-Lopez A, Bañares L, García-Vela A. Photodissociation of the CH2Br radical: A theoretical study. J Chem Phys 2024; 160:074301. [PMID: 38364009 DOI: 10.1063/5.0187546] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2023] [Accepted: 12/21/2023] [Indexed: 02/18/2024] Open
Abstract
Bromine atom (Br) reactions lead to ozone depletion in the troposphere and stratosphere. Photodegradation of bromocarbons is one of the main sources of bromine atoms in the atmosphere. Here, we use high-level ab initio methods, including spin-orbit effects, to study the photodissociation of the CH2Br radical. All possible fragmentation pathways, namely CH2Br + hν → CH2 + Br, HCBr + H, and CBr + H2, have been analyzed. Potential-energy curves of the ground and several excited electronic states along the corresponding dissociating bond distance of each pathway have been calculated. Considering the actinic fluxes of solar irradiation in the troposphere and in the stratosphere in the relevant range of frequencies, it is found that the first five excited states of CH2Br can be accessed from the ground state. Analysis of the potential curves shows that the pathways producing CH2 + Br and HCBr + H can proceed through a fast direct dissociation mechanism, while the pathway leading to CBr + H2 involves much slower dissociation mechanisms like internal conversion between electronic states, predissociation, or tunneling through exit barriers. The main implications are that the two faster channels are predicted to be dominant, and the slower pathway is expected to be less relevant. The tropospheric and stratospheric solar actinic fluxes also allow for further dissociation of the HCBr and CBr fragments, generating additional Br atoms, provided that they survive possible collisions with other atmospheric reagents. Finally, we discuss the possible effect of each of the three CH2Br dissociation pathways on the depletion of atmospheric ozone.
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Affiliation(s)
- F Charfeddine
- Laboratoire de Spectroscopie Atomique, Moleculaire et Applications-LSAMA LR01ES09, Faculte des Sciences de Tunis, Universite de Tunis El Manar, 2092 Tunis, Tunisia
- Instituto de Física Fundamental, Consejo Superior de Investigaciones Científicas, Serrano 123, 28006 Madrid, Spain
| | - A Zanchet
- Instituto de Física Fundamental, Consejo Superior de Investigaciones Científicas, Serrano 123, 28006 Madrid, Spain
| | - O Yazidi
- Laboratoire de Spectroscopie Atomique, Moleculaire et Applications-LSAMA LR01ES09, Faculte des Sciences de Tunis, Universite de Tunis El Manar, 2092 Tunis, Tunisia
| | - C A Cuevas
- Department of Atmospheric Chemistry and Climate, Institute of Physical Chemistry Blas Cabrera, CSIC, 28006 Madrid, Spain
| | - A Saiz-Lopez
- Department of Atmospheric Chemistry and Climate, Institute of Physical Chemistry Blas Cabrera, CSIC, 28006 Madrid, Spain
| | - L Bañares
- Departamento de Química Física, Facultad de Ciencias Químicas, Universidad Complutense de Madrid (Unidad Asociada I+D+i CSIC), 28040 Madrid, Spain
- Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA-Nanoscience), 28049 Madrid, Spain
| | - A García-Vela
- Instituto de Física Fundamental, Consejo Superior de Investigaciones Científicas, Serrano 123, 28006 Madrid, Spain
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3
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Bouallagui A, Zanchet A, Bañares L, García-Vela A. An ab initio study of the photodissociation of CH 2I and CH 2I . Phys Chem Chem Phys 2023. [PMID: 37465906 DOI: 10.1039/d3cp01460f] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/20/2023]
Abstract
Photodissociation of the CH2I radical and the CH2I+ cation is studied by means of high-level ab initio calculations, including spin-orbit effects. Potential-energy curves (PEC) along the dissociating bond distances involved in some fragmentation pathways of these species are computed for the ground and several excited electronic states. Based on the PECs obtained, the possible photodissociation mechanisms are analyzed and suggested. Significant differences are found between the fragmentation dynamics of the neutral radical and that of the cation. While a relatively simple dissociation dynamics is predicted for CH2I, more complex fragmentation mechanisms involving internal conversion and couplings between different excited electronic states are expected for CH2I+. The species studied here are relevant to atmospheric chemistry, and the present work can help to understand better how their photodissociation may affect chemical processes in the atmosphere.
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Affiliation(s)
- A Bouallagui
- Laboratoire de Spectroscopie Atomique, Moléculaire et Applications-LSAMA LR01ES09, Faculté des Sciences de Tunis, Université de Tunis El Manar, 2092, Tunis, Tunisia
- Instituto de Física Fundamental, Consejo Superior de Investigaciones Científicas, Serrano 123, 28006 Madrid, Spain.
| | - A Zanchet
- Instituto de Física Fundamental, Consejo Superior de Investigaciones Científicas, Serrano 123, 28006 Madrid, Spain.
| | - L Bañares
- Departamento de Química Física, Facultad de Ciencias Químicas, Universidad Complutense de Madrid (Unidad Asociada I+D+i CSIC), 28040 Madrid, Spain
- Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA-Nanoscience), 28049 Madrid, Spain
| | - A García-Vela
- Instituto de Física Fundamental, Consejo Superior de Investigaciones Científicas, Serrano 123, 28006 Madrid, Spain.
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4
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Arndt C, Hristov AN, Price WJ, McClelland SC, Pelaez AM, Cueva SF, Oh J, Dijkstra J, Bannink A, Bayat AR, Crompton LA, Eugène MA, Enahoro D, Kebreab E, Kreuzer M, McGee M, Martin C, Newbold CJ, Reynolds CK, Schwarm A, Shingfield KJ, Veneman JB, Yáñez-Ruiz DR, Yu Z. Full adoption of the most effective strategies to mitigate methane emissions by ruminants can help meet the 1.5 °C target by 2030 but not 2050. Proc Natl Acad Sci U S A 2022; 119:e2111294119. [PMID: 35537050 PMCID: PMC9171756 DOI: 10.1073/pnas.2111294119] [Citation(s) in RCA: 67] [Impact Index Per Article: 33.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Accepted: 02/08/2022] [Indexed: 01/03/2023] Open
Abstract
To meet the 1.5 °C target, methane (CH4) from ruminants must be reduced by 11 to 30% by 2030 and 24 to 47% by 2050 compared to 2010 levels. A meta-analysis identified strategies to decrease product-based (PB; CH4 per unit meat or milk) and absolute (ABS) enteric CH4 emissions while maintaining or increasing animal productivity (AP; weight gain or milk yield). Next, the potential of different adoption rates of one PB or one ABS strategy to contribute to the 1.5 °C target was estimated. The database included findings from 430 peer-reviewed studies, which reported 98 mitigation strategies that can be classified into three categories: animal and feed management, diet formulation, and rumen manipulation. A random-effects meta-analysis weighted by inverse variance was carried out. Three PB strategies—namely, increasing feeding level, decreasing grass maturity, and decreasing dietary forage-to-concentrate ratio—decreased CH4 per unit meat or milk by on average 12% and increased AP by a median of 17%. Five ABS strategies—namely CH4 inhibitors, tanniferous forages, electron sinks, oils and fats, and oilseeds—decreased daily methane by on average 21%. Globally, only 100% adoption of the most effective PB and ABS strategies can meet the 1.5 °C target by 2030 but not 2050, because mitigation effects are offset by projected increases in CH4 due to increasing milk and meat demand. Notably, by 2030 and 2050, low- and middle-income countries may not meet their contribution to the 1.5 °C target for this same reason, whereas high-income countries could meet their contributions due to only a minor projected increase in enteric CH4 emissions.
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Affiliation(s)
- Claudia Arndt
- Integrated Sciences Division, International Livestock Research Institute (ILRI), 00100 Nairobi, Kenya
| | - Alexander N. Hristov
- Department of Animal Science, The Pennsylvania State University, University Park, PA 16802
| | - William J. Price
- College of Agricultural and Life Sciences, University of Idaho, Moscow, ID 83844
| | - Shelby C. McClelland
- Department of Soil and Crop Sciences, Colorado State University, Fort Collins, CO 80523
| | - Amalia M. Pelaez
- Department of Animal Science, The Pennsylvania State University, University Park, PA 16802
- Animal Sciences Group, Wageningen University and Research, 6708 PB Wageningen, The Netherlands
| | - Sergio F. Cueva
- Department of Animal Science, The Pennsylvania State University, University Park, PA 16802
| | - Joonpyo Oh
- Department of Animal Science, The Pennsylvania State University, University Park, PA 16802
| | - Jan Dijkstra
- Animal Sciences Group, Wageningen University and Research, 6708 PB Wageningen, The Netherlands
| | - André Bannink
- Animal Sciences Group, Wageningen University and Research, 6708 PB Wageningen, The Netherlands
| | - Ali R. Bayat
- Natural Resources Institute Finland, 00790 Helsinki, Finland
| | - Les A. Crompton
- School of Agriculture, Policy and Development, University of Reading, Reading RG6 6EU, United Kingdom
| | - Maguy A. Eugène
- Institut national de recherche pour l'agriculture, l'alimentation et l'environnement (INRAE), VetAgro Sup, UMR Herbivores, Université Clermont Auvergne, 63122 Saint-Genès-Champanelle, France
| | - Dolapo Enahoro
- Integrated Sciences Division, International Livestock Research Institute (ILRI), 00100 Nairobi, Kenya
| | - Ermias Kebreab
- College of Agricultural and Environmental Sciences, University of California, Davis, CA 95616
| | - Michael Kreuzer
- Department of Environmental Systems Science, ETH Zurich, 8092 Zürich, Switzerland
| | - Mark McGee
- Animal & Grassland Research and Innovation Centre (AGRIC), Teagasc, Grange C15 PW93, Ireland
| | - Cécile Martin
- Institut national de recherche pour l'agriculture, l'alimentation et l'environnement (INRAE), VetAgro Sup, UMR Herbivores, Université Clermont Auvergne, 63122 Saint-Genès-Champanelle, France
| | | | - Christopher K. Reynolds
- School of Agriculture, Policy and Development, University of Reading, Reading RG6 6EU, United Kingdom
| | - Angela Schwarm
- Department of Animal and Aquacultural Sciences, Norwegian University of Life Sciences, 1432 Aas, Norway
| | | | | | - David R. Yáñez-Ruiz
- Estación Experimental del Zaidín (EEZ), Consejo Superior de Investigaciones Científicas (CSIC), 18008 Granada, Spain
| | - Zhongtang Yu
- Department of Animal Sciences, The Ohio State University, Columbus, OH 43210
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5
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An M, Western LM, Say D, Chen L, Claxton T, Ganesan AL, Hossaini R, Krummel PB, Manning AJ, Mühle J, O'Doherty S, Prinn RG, Weiss RF, Young D, Hu J, Yao B, Rigby M. Rapid increase in dichloromethane emissions from China inferred through atmospheric observations. Nat Commun 2021; 12:7279. [PMID: 34907196 PMCID: PMC8671471 DOI: 10.1038/s41467-021-27592-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Accepted: 11/30/2021] [Indexed: 12/03/2022] Open
Abstract
With the successful implementation of the Montreal Protocol on Substances that Deplete the Ozone Layer, the atmospheric abundance of ozone-depleting substances continues to decrease slowly and the Antarctic ozone hole is showing signs of recovery. However, growing emissions of unregulated short-lived anthropogenic chlorocarbons are offsetting some of these gains. Here, we report an increase in emissions from China of the industrially produced chlorocarbon, dichloromethane (CH2Cl2). The emissions grew from 231 (213-245) Gg yr-1 in 2011 to 628 (599-658) Gg yr-1 in 2019, with an average annual increase of 13 (12-15) %, primarily from eastern China. The overall increase in CH2Cl2 emissions from China has the same magnitude as the global emission rise of 354 (281-427) Gg yr-1 over the same period. If global CH2Cl2 emissions remain at 2019 levels, they could lead to a delay in Antarctic ozone recovery of around 5 years compared to a scenario with no CH2Cl2 emissions.
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Affiliation(s)
- Minde An
- College of Environmental Sciences and Engineering, Peking University, Beijing, China
- School of Chemistry, University of Bristol, Bristol, UK
| | | | - Daniel Say
- School of Chemistry, University of Bristol, Bristol, UK
| | - Liqu Chen
- Meteorological Observation Centre of China Meteorological Administration (MOC/CMA), Beijing, China
| | - Tom Claxton
- Lancaster Environment Centre, Lancaster University, Lancaster, UK
| | - Anita L Ganesan
- School of Geographical Sciences, University of Bristol, Bristol, UK
| | - Ryan Hossaini
- Lancaster Environment Centre, Lancaster University, Lancaster, UK
- Centre of Excellence in Environmental Data Science, Lancaster University, Lancaster, UK
| | - Paul B Krummel
- Climate Science Centre, CSIRO Oceans and Atmosphere, Aspendale, VIC, Australia
| | | | - Jens Mühle
- Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA, USA
| | | | - Ronald G Prinn
- Center for Global Change Science, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Ray F Weiss
- Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA, USA
| | - Dickon Young
- School of Chemistry, University of Bristol, Bristol, UK
| | - Jianxin Hu
- College of Environmental Sciences and Engineering, Peking University, Beijing, China.
| | - Bo Yao
- Meteorological Observation Centre of China Meteorological Administration (MOC/CMA), Beijing, China.
- Department of Atmospheric and Oceanic Sciences & Institute of Atmospheric Sciences, Fudan University, Shanghai, China.
| | - Matthew Rigby
- School of Chemistry, University of Bristol, Bristol, UK.
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6
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Mohd Hanif N, Limi Hawari NSS, Othman M, Abd Hamid HH, Ahamad F, Uning R, Ooi MCG, Wahab MIA, Sahani M, Latif MT. Ambient volatile organic compounds in tropical environments: Potential sources, composition and impacts - A review. CHEMOSPHERE 2021; 285:131355. [PMID: 34710962 DOI: 10.1016/j.chemosphere.2021.131355] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Revised: 06/16/2021] [Accepted: 06/26/2021] [Indexed: 06/13/2023]
Abstract
Volatile organic compounds (VOCs) are widely recognized to affect the environment and human health. This review provides a comprehensive presentation of the types and levels of VOCs, their sources and potential effects on human health and the environment based on past and current observations made at tropical sites. Isoprene was found to be the dominant biogenic VOC in the tropics. Tropical broad leaf evergreen trees are the main emitters of isoprene, making up more than 70% of the total emissions. The VOCs found in the tropical remote marine atmosphere included isoprene (>100 ppt), dimethyl sulfide (≤100 ppt) and halocarbons, i.e. bromoform (≤8.4 ppt), dibromomethane (≤2.7 ppt) and dibromochloromethane (≤1.6 ppt). VOCs such as benzene, toluene, ethylbenzene and xylene (BTEX) are the most monitored anthropogenic VOCs and are present mainly due to motor vehicles emissions. Additionally, biomass burning contributes to anthropogenic VOCs, especially high molecular weight VOCs, e.g. methanol and acetonitrile. The relative contributions of VOC species to ozone are determined through the level of the Ozone Formation Potential (OFP) of different species. Emissions of VOCs (e.g. very short-lived halogenated gases) in the tropics are capable of contributing to stratospheric ozone depletion. BTEX has been identified as the main types of VOCs that are associated with the cancer risk in urban areas in tropical regions. Finally, future studies related to VOCs in the tropics and their associated health risks are needed to address these concerns.
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Affiliation(s)
- Norfazrin Mohd Hanif
- Department of Earth Sciences and Environment, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600, Bangi, Selangor, Malaysia.
| | - Nor Syamimi Sufiera Limi Hawari
- Department of Earth Sciences and Environment, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600, Bangi, Selangor, Malaysia
| | - Murnira Othman
- Institute for Environment and Development (LESTARI), Universiti Kebangsaan Malaysia, 43600, Bangi, Selangor, Malaysia
| | - Haris Hafizal Abd Hamid
- Department of Earth Sciences and Environment, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600, Bangi, Selangor, Malaysia
| | - Fatimah Ahamad
- AQ Expert Solutions, Jalan Dato Muda Linggi, Seremban, 70100, Negeri Sembilan, Malaysia
| | - Royston Uning
- Institute of Oceanography and Environment, Universiti Malaysia Terengganu, 21030, Kuala Nerus, Terengganu, Malaysia
| | - Maggie Chel Gee Ooi
- Institute of Climate Change, Universiti Kebangsaan Malaysia, 43600, Bangi, Selangor, Malaysia
| | - Muhammad Ikram A Wahab
- Environmental Health and Industrial Safety Program, Center for Health and Applied Sciences, Faculty of Health Sciences, Universiti Kebangsaan Malaysia, Kuala Lumpur, 50300, Malaysia
| | - Mazrura Sahani
- Environmental Health and Industrial Safety Program, Center for Health and Applied Sciences, Faculty of Health Sciences, Universiti Kebangsaan Malaysia, Kuala Lumpur, 50300, Malaysia
| | - Mohd Talib Latif
- Department of Earth Sciences and Environment, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600, Bangi, Selangor, Malaysia
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7
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Xiao Y, Wang J, Ma X, Ji Y, Ji Y. Extremely rapid self-reactions of hydrochlorofluoromethanes and hydrochlorofluoroethanes and implications in destruction of ozone. Chem Phys Lett 2021. [DOI: 10.1016/j.cplett.2021.138867] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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8
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Thapa HR, Agarwal V. Obligate Brominating Enzymes Underlie Bromoform Production by Marine Cyanobacteria. JOURNAL OF PHYCOLOGY 2021; 57:1131-1139. [PMID: 33556207 DOI: 10.1111/jpy.13142] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2020] [Revised: 01/02/2021] [Accepted: 01/14/2021] [Indexed: 06/12/2023]
Abstract
Marine algae are prolific producers of bromoform (CHBr3 ). This naturally produced molecule is a potent environmental pollutant as it volatilizes into the atmosphere and contributes to depletion of the ozone layer in a manner akin to, and in magnitude similar to, man-made chlorofluorocarbons. While phototrophs such as seaweeds, diatoms, and dinoflagellates are known sources of bromoform, additional as yet unknown biogenetic sources of bromoform exist in the oceans. Here, using halogenating enzymes as diagnostic genetic elements, we demonstrate that marine cyanobacteria also possess the enzymological potential for bromoform production. Using recombinantly purified vanadium-dependent bromoperoxidases from planktonic and bloom-forming marine cyanobacteria in in vitro biochemical assays, we reconstitute the enzymatic production of bromoform. We find cyanobacterial bromoform synthesizing enzymes to be obligate brominases possessing no chlorinating activities. These results expand the repertoire of marine biotic sources that introduce this pollutant in the atmosphere.
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Affiliation(s)
- Hem R Thapa
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA, USA
| | - Vinayak Agarwal
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA, USA
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA
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9
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Liu SS, Yang GP, He Z, Gao XX, Xu F. Oceanic emissions of methyl halides and effect of nutrients concentration on their production: A case of the western Pacific Ocean (2°N to 24°N). THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 769:144488. [PMID: 33485203 DOI: 10.1016/j.scitotenv.2020.144488] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2020] [Revised: 12/08/2020] [Accepted: 12/09/2020] [Indexed: 06/12/2023]
Abstract
Methyl halides are important greenhouse gases responsible for the majority of the ozone layer depletion. This study investigated atmospheric and seawater methyl halides (CH3Cl, CH3Br, and CH3I) in the western Pacific Ocean between 2°N and 24°N. Increases in methyl halides in the atmosphere were likely to have originated from Southeast Asian regions. Elevated CH3I concentrations in seawater were mainly produced photochemically from dissolved organic carbon. Maximum methyl halide and chlorophyll a levels in the upper water column (0-200 m) were linked to biological activity and downwelling or upwelling caused by cold and warm eddies. Ship-based incubation experiments showed that nutrient supplementation promoted methyl halide emissions. The elevated methyl halide production was associated with increases in phytoplankton such as diatoms. The mean fluxes of CH3Cl, CH3Br, and CH3I in study area of during the cruise were 82.91, 4.70, and 3.50 nmol m-2 d-1, respectively. The estimated emissions of CH3Cl, CH3Br, and CH3I in the western Pacific Ocean accounted for 0.67%, 0.79% and 0.09% of global oceanic emissions, respectively, indicating that the open sea contribute insignificantly to the global oceanic emissions of these gases.
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Affiliation(s)
- Shan-Shan Liu
- Frontiers Science Center for Deep Ocean Multispheres and Earth System, Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao 266100, China
| | - Gui-Peng Yang
- Frontiers Science Center for Deep Ocean Multispheres and Earth System, Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao 266100, China; Laboratory for Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266237, China; Institute of Marine Chemistry, Ocean University of China, Qingdao 266100, China
| | - Zhen He
- Frontiers Science Center for Deep Ocean Multispheres and Earth System, Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao 266100, China; Laboratory for Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266237, China.
| | - Xu-Xu Gao
- Frontiers Science Center for Deep Ocean Multispheres and Earth System, Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao 266100, China
| | - Feng Xu
- Frontiers Science Center for Deep Ocean Multispheres and Earth System, Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao 266100, China
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10
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Thapa HR, Lin Z, Yi D, Smith JE, Schmidt EW, Agarwal V. Genetic and Biochemical Reconstitution of Bromoform Biosynthesis in Asparagopsis Lends Insights into Seaweed Reactive Oxygen Species Enzymology. ACS Chem Biol 2020; 15:1662-1670. [PMID: 32453942 DOI: 10.1021/acschembio.0c00299] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Marine macroalgae, seaweeds, are exceptionally prolific producers of halogenated natural products. Biosynthesis of halogenated molecules in seaweeds is inextricably linked to reactive oxygen species (ROS) signaling as hydrogen peroxide serves as a substrate for haloperoxidase enzymes that participate in the construction these halogenated molecules. Here, using red macroalga Asparagopsis taxiformis, a prolific producer of the ozone depleting molecule bromoform, we provide the discovery and biochemical characterization of a ROS-producing NAD(P)H oxidase from seaweeds. This discovery was enabled by our sequencing of Asparagopsis genomes, in which we find the gene encoding the ROS-producing enzyme to be clustered with genes encoding bromoform-producing haloperoxidases. Biochemical reconstitution of haloperoxidase activities establishes that fatty acid biosynthesis can provide viable hydrocarbon substrates for bromoform production. The ROS production haloperoxidase enzymology that we describe here advances seaweed biology and biochemistry by providing the molecular basis for decades worth of physiological observations in ROS and halogenated natural product biosyntheses.
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Affiliation(s)
- Hem R. Thapa
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Zhenjian Lin
- Department of Medicinal Chemistry, University of Utah, Salt Lake City, Utah 84112, United States
| | - Dongqi Yi
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Jennifer E. Smith
- Center for Marine Biodiversity and Conservation, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California 92093, United States
| | - Eric W. Schmidt
- Department of Medicinal Chemistry, University of Utah, Salt Lake City, Utah 84112, United States
| | - Vinayak Agarwal
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
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11
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Gahlaut A, Paranjothy M. Theoretical investigation of the dissociation chemistry of formyl halides in the gas phase. Phys Chem Chem Phys 2020; 22:20069-20077. [DOI: 10.1039/d0cp02126a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Halogen substituted analogues of formaldehyde, HXCO (X = F, Cl, Br, and I), play a crucial role in the degradation of stratospheric ozone.
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Affiliation(s)
- Anchal Gahlaut
- Department of Chemistry
- Indian Institute of Technology Jodhpur
- Jodhpur
- India
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12
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Godara S, Paranjothy M. Competing Molecular and Radical Pathways in the Dissociation of Halons via Direct Chemical Dynamics Simulations. J Phys Chem A 2019; 123:8527-8535. [PMID: 31539256 DOI: 10.1021/acs.jpca.9b06564] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
A great deal of attention has been given to the decomposition chemistry of halons (halomethanes) due to their role in stratospheric ozone depletion. Knowledge of certain aspects of dissociation of halons such as the competition between radical and molecular pathways and their mechanistic details is limited. Halon molecules can isomerize to an iso form containing a halogen-halogen bond and such iso-halon forms have been identified as intermediates in condensed phase chemistry. Recently, a quantum chemistry study of role of iso-halons in the gas phase decomposition of halomethanes has been reported. In the present work, we have investigated the ground state dissociation chemistry of select halon molecules - CF2Cl2, CF2Br2, CHBr3, and CH2BrCl using electronic structure theory calculations and direct chemical dynamics simulations. Classical trajectories were generated on-the-fly using density functional PBE0/6-31G* level of theory at a fixed total energy. Simulation results showed that molecular products, in general, were dominant for all the four molecules at the chosen energy. A variety of mechanisms such as direct dissociation via multicenter transition states, decomposition via isomerization, radical recombinations, and roaming pathways contributed to the formation of molecular products. Atomic level mechanisms are presented, and the role of iso-halons in the gas phase chemistry of halomethanes is clearly established.
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Affiliation(s)
- Sumitra Godara
- Department of Chemistry , Indian Institute of Technology Jodhpur , Jodhpur , 342037 Rajasthan , India
| | - Manikandan Paranjothy
- Department of Chemistry , Indian Institute of Technology Jodhpur , Jodhpur , 342037 Rajasthan , India
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13
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Hossaini R, Atlas E, Dhomse SS, Chipperfield MP, Bernath PF, Fernando AM, Mühle J, Leeson AA, Montzka SA, Feng W, Harrison JJ, Krummel P, Vollmer MK, Reimann S, O'Doherty S, Young D, Maione M, Arduini J, Lunder CR. Recent Trends in Stratospheric Chlorine From Very Short-Lived Substances. JOURNAL OF GEOPHYSICAL RESEARCH. ATMOSPHERES : JGR 2019; 124:2318-2335. [PMID: 30984484 PMCID: PMC6446807 DOI: 10.1029/2018jd029400] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2018] [Revised: 01/02/2019] [Accepted: 01/08/2019] [Indexed: 05/15/2023]
Abstract
Very short-lived substances (VSLS), including dichloromethane (CH2Cl2), chloroform (CHCl3), perchloroethylene (C2Cl4), and 1,2-dichloroethane (C2H4Cl2), are a stratospheric chlorine source and therefore contribute to ozone depletion. We quantify stratospheric chlorine trends from these VSLS (VSLCltot) using a chemical transport model and atmospheric measurements, including novel high-altitude aircraft data from the NASA VIRGAS (2015) and POSIDON (2016) missions. We estimate VSLCltot increased from 69 (±14) parts per trillion (ppt) Cl in 2000 to 111 (±22) ppt Cl in 2017, with >80% delivered to the stratosphere through source gas injection, and the remainder from product gases. The modeled evolution of chlorine source gas injection agrees well with historical aircraft data, which corroborate reported surface CH2Cl2 increases since the mid-2000s. The relative contribution of VSLS to total stratospheric chlorine increased from ~2% in 2000 to ~3.4% in 2017, reflecting both VSLS growth and decreases in long-lived halocarbons. We derive a mean VSLCltot growth rate of 3.8 (±0.3) ppt Cl/year between 2004 and 2017, though year-to-year growth rates are variable and were small or negative in the period 2015-2017. Whether this is a transient effect, or longer-term stabilization, requires monitoring. In the upper stratosphere, the modeled rate of HCl decline (2004-2017) is -5.2% per decade with VSLS included, in good agreement to ACE satellite data (-4.8% per decade), and 15% slower than a model simulation without VSLS. Thus, VSLS have offset a portion of stratospheric chlorine reductions since the mid-2000s.
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Affiliation(s)
- Ryan Hossaini
- Lancaster Environment CentreLancaster UniversityLancasterUK
| | - Elliot Atlas
- Rosenstiel School of Marine and Atmospheric Science (RSMAS)University of MiamiCoral GablesFLUSA
| | | | | | - Peter F. Bernath
- Department of Chemistry and BiochemistryOld Dominion UniversityNorfolkVAUSA
- Department of ChemistryUniversity of WaterlooWaterlooONCanada
| | | | - Jens Mühle
- Scripps Institution of OceanographyUniversity of California San DiegoLa JollaCAUSA
| | | | | | - Wuhu Feng
- School of Earth and EnvironmentUniversity of LeedsLeedsUK
- NCASUniversity of LeedsLeedsUK
| | - Jeremy J. Harrison
- Department of Physics and AstronomyUniversity of LeicesterLeicesterUK
- National Centre for Earth ObservationUniversity of LeicesterLeicesterUK
| | - Paul Krummel
- Climate Science CentreCSIRO Oceans and AtmosphereAspendaleVictoriaAustralia
| | - Martin K. Vollmer
- Laboratory for Air Pollution and Environmental TechnologyEmpa, Swiss Federal Laboratories for Materials Science and TechnologyDuebendorfSwitzerland
| | - Stefan Reimann
- Laboratory for Air Pollution and Environmental TechnologyEmpa, Swiss Federal Laboratories for Materials Science and TechnologyDuebendorfSwitzerland
| | | | - Dickon Young
- School of ChemistryUniversity of BristolBristolUK
| | - Michela Maione
- Department of Pure and Applied SciencesUniversity of UrbinoUrbinoItaly
| | - Jgor Arduini
- Department of Pure and Applied SciencesUniversity of UrbinoUrbinoItaly
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14
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Hossaini R, Chipperfield MP, Montzka SA, Leeson AA, Dhomse SS, Pyle JA. The increasing threat to stratospheric ozone from dichloromethane. Nat Commun 2017; 8:15962. [PMID: 28654085 PMCID: PMC5490265 DOI: 10.1038/ncomms15962] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2016] [Accepted: 05/16/2017] [Indexed: 11/29/2022] Open
Abstract
It is well established that anthropogenic chlorine-containing chemicals contribute to ozone layer depletion. The successful implementation of the Montreal Protocol has led to reductions in the atmospheric concentration of many ozone-depleting gases, such as chlorofluorocarbons. As a consequence, stratospheric chlorine levels are declining and ozone is projected to return to levels observed pre-1980 later this century. However, recent observations show the atmospheric concentration of dichloromethane—an ozone-depleting gas not controlled by the Montreal Protocol—is increasing rapidly. Using atmospheric model simulations, we show that although currently modest, the impact of dichloromethane on ozone has increased markedly in recent years and if these increases continue into the future, the return of Antarctic ozone to pre-1980 levels could be substantially delayed. Sustained growth in dichloromethane would therefore offset some of the gains achieved by the Montreal Protocol, further delaying recovery of Earth’s ozone layer. Chlorine-containing species deplete stratospheric ozone and while chlorofluorocarbons have been drastically reduced, dichloromethane concentrations have recently increased rapidly. Hossaini et al. show that continued growth at this rate could result in important delays to Antarctic ozone recovery.
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Affiliation(s)
- Ryan Hossaini
- Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, UK
| | - Martyn P Chipperfield
- School of Earth and Environment, University of Leeds, Leeds LS2 9JT, UK.,National Centre for Earth Observation, University of Leeds, Leeds LS2 9JT, UK
| | - Stephen A Montzka
- National Oceanic and Atmospheric Administration, Boulder, Colorado 80305, USA
| | - Amber A Leeson
- Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, UK
| | - Sandip S Dhomse
- School of Earth and Environment, University of Leeds, Leeds LS2 9JT, UK.,National Centre for Earth Observation, University of Leeds, Leeds LS2 9JT, UK
| | - John A Pyle
- Department of Chemistry, University of Cambridge, Cambridge CB2 1EW, UK.,National Centre for Atmospheric Science, University of Cambridge, Cambridge CB2 1EW, UK
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