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Liu H, Duan H, Zhang N, Ma Y, Liu G, Miller TR, Mao R, Xu M, Li J, Yang J. Rethinking time-lagged emissions and abatement potential of fluorocarbons in the post-Kigali Amendment era. Nat Commun 2024; 15:6687. [PMID: 39107310 PMCID: PMC11303384 DOI: 10.1038/s41467-024-51113-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Accepted: 07/29/2024] [Indexed: 08/10/2024] Open
Abstract
The Montreal Protocol has been successful in safeguarding the ozone layer and curbing climate change. However, accurately estimating and reducing the time-lagged emissions of ozone-depleting substances or their substitutes, such as produced but not-yet-emitted fluorocarbon banks, remains a significant challenge. Here, we use a dynamic material flow analysis model to characterize the global stocks and flows of two fluorocarbon categories, hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs), from 1986 to 2060. We assess emission pathways, time-lagged emission sizes, and potential abatement measures throughout different life cycle stages while focusing on the role of banked fluorocarbons in global and regional decarbonization efforts in the post-Kigali Amendment era. Although fluorocarbon releases are expected to decline, the cumulative global warming potential (GWP)-weighted emissions of HCFCs and HFCs are significant; these will be 6.4 (±1.2) and 14.8 (±2.5) gigatons CO2-equivalent, respectively, in 2022-2060 in our business-as-usual (BAU) scenario. Scenario analysis demonstrates that implementing currently available best environmental practices in developed economies can reduce cumulative GWP-weighted emissions by up to 45% compared with the BAU scenario.
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Affiliation(s)
- Heping Liu
- Guangdong Provincial Key Laboratory of Petrochemical Pollution Process and Control, School of Environmental Science and Engineering, Guangdong University of Petrochemical Technology, Maoming, Guangdong, China
| | - Huabo Duan
- School of Environmental Science and Engineering, Hubei Key Laboratory of Multi-media Pollution Cooperative Control in Yangtze Basin, Huazhong University of Science and Technology, Wuhan, China.
| | - Ning Zhang
- Leibniz Institute of Ecological Urban and Regional Development (IOER), Dresden, Germany
| | - Yin Ma
- Guangdong Provincial Key Laboratory of Petrochemical Pollution Process and Control, School of Environmental Science and Engineering, Guangdong University of Petrochemical Technology, Maoming, Guangdong, China
| | - Gang Liu
- College of Urban and Environmental Sciences, Peking University, Beijing, China
- Institute of Carbon Neutrality, Peking University, Beijing, China
| | - Travis Reed Miller
- Department of Civil and Environmental Engineering, University of Maine, Orono, ME, USA
| | - Ruichang Mao
- DTU Sustain, Department of Environmental & Resource Engineering, Technical University of Denmark, Lyngby, Denmark
| | - Ming Xu
- School of Environment, Tsinghua University, Beijing, China
| | - Jinhui Li
- School of Environment, Tsinghua University, Beijing, China
| | - Jiakuan Yang
- School of Environmental Science and Engineering, Hubei Key Laboratory of Multi-media Pollution Cooperative Control in Yangtze Basin, Huazhong University of Science and Technology, Wuhan, China.
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2
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Dierick BJH, Eikholt AA, van de Hei SJ, Muris JWM, Kerstjens HAM, van Boven JFM. Reshaping respiratory care: potential advances in inhaled pharmacotherapy in asthma. Expert Opin Pharmacother 2024; 25:1507-1516. [PMID: 39099418 DOI: 10.1080/14656566.2024.2389258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2024] [Revised: 07/30/2024] [Accepted: 08/02/2024] [Indexed: 08/06/2024]
Abstract
INTRODUCTION Asthma is a common disease with a global burden of 358 million patients. Despite improvements in pharmacological and non-pharmacological treatments, many patients still do not achieve complete asthma control. Therefore, innovative pharmacotherapy is important. AREAS COVERED Following a semi-structured search in Pubmed, an overview of advances in inhaled asthma therapy is provided, looking at innovations in digital inhalers, eco-friendly inhalers and novel inhaled biologic therapies, antibiotics and vaccines, as well as other potential novel asthma therapy targets. EXPERT OPINION Digital inhalers, sending reminders and monitoring inhalation technique electronically, can support medication adherence and improve asthma control. To reduce the global warming potential of traditional aerosols used in pressurized metered-dose inhalers (HFA-134a, HFA-227ea), greener alternatives are under development (HFA-152a, HFO-1234ze) that are expected to be available by 2025. Current pharmacological advances in asthma therapy are mainly achieved by novel biologicals (anti-IgE, anti-IL5, anti-IL4/13, and anti-TSLP) targeting specific severe asthma phenotypes. While injection is the usual administration route for biologics and vaccines used in asthma, inhalation is an option being explored, although several (mainly formulation) challenges need to be overcome. Other potential novel future inhaled asthma therapies include anti-IL-33/ST2 biologicals and JAK inhibitors, all still requiring more clinical evidence.
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Affiliation(s)
- Boudewijn J H Dierick
- Department of Clinical Pharmacy & Pharmacology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
- Groningen Research Institute for Asthma and COPD (GRIAC), Groningen, The Netherlands
- Department of Primary and Long-term Care, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Amber A Eikholt
- Department of Clinical Pharmacy & Pharmacology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
- Groningen Research Institute for Asthma and COPD (GRIAC), Groningen, The Netherlands
| | - Susanne J van de Hei
- Department of Clinical Pharmacy & Pharmacology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
- Groningen Research Institute for Asthma and COPD (GRIAC), Groningen, The Netherlands
| | - Jean W M Muris
- Department of General Practice, Research Institute CAPHRI, Maastricht University, Maastricht, The Netherlands
| | - Huib A M Kerstjens
- Groningen Research Institute for Asthma and COPD (GRIAC), Groningen, The Netherlands
- Department of Pulmonary Diseases and Tuberculosis, University of Groningen University Medical Center Groningen, Groningen, The Netherlands
| | - Job F M van Boven
- Department of Clinical Pharmacy & Pharmacology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
- Groningen Research Institute for Asthma and COPD (GRIAC), Groningen, The Netherlands
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3
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Lye K, Young RD. A review of frustrated Lewis pair enabled monoselective C-F bond activation. Chem Sci 2024; 15:2712-2724. [PMID: 38404400 PMCID: PMC10882520 DOI: 10.1039/d3sc06485a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2023] [Accepted: 01/07/2024] [Indexed: 02/27/2024] Open
Abstract
Frustrated Lewis pair (FLP) bond activation chemistry has greatly developed over the last two decades since the seminal report of metal-free reversible hydrogen activation. Recently, FLP systems have been utilized to allow monoselective C-F bond activation (at equivalent sites) in polyfluoroalkanes. The problem of 'over-defluorination' in the functionalization of polyfluoroalkanes (where multiple fluoro-positions are uncontrollably functionalized) has been a long-standing chemical problem in fluorocarbon chemistry for over 80 years. FLP mediated monoselective C-F bond activation is complementary to other solutions developed to address 'over-defluorination' and offers several advantages and unique opportunities. This perspective highlights some of these advantages and opportunities and places the development of FLP mediated C-F bond activation into the context of the wider effort to overcome 'over-defluorination'.
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Affiliation(s)
- Kenneth Lye
- Department of Chemistry, National University of Singapore 117543 Singapore
| | - Rowan D Young
- School of Chemistry and Molecular Biosciences, The University of Queensland St Lucia 4072 Australia
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4
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Hartz WF, Björnsdotter MK, Yeung LWY, Hodson A, Thomas ER, Humby JD, Day C, Jogsten IE, Kärrman A, Kallenborn R. Levels and distribution profiles of Per- and Polyfluoroalkyl Substances (PFAS) in a high Arctic Svalbard ice core. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 871:161830. [PMID: 36716880 DOI: 10.1016/j.scitotenv.2023.161830] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Revised: 01/20/2023] [Accepted: 01/21/2023] [Indexed: 06/18/2023]
Abstract
Per- and polyfluoroalkyl substances (PFAS) are a group of persistent organic contaminants of which some are toxic and bioaccumulative. Several PFAS can be formed from the atmospheric degradation of precursors such as fluorotelomer alcohols (FTOHs) as well as hydrochlorofluorocarbons (HFCs) and other ozone-depleting chlorofluorocarbon (CFC) replacement compounds. Svalbard ice cores have been shown to provide a valuable record of long-range atmospheric transport of contaminants to the Arctic. This study uses a 12.3 m ice core from the remote Lomonosovfonna ice cap on Svalbard to understand the atmospheric deposition of PFAS in the Arctic. A total of 45 PFAS were targeted, of which 26 were detected, using supercritical fluid chromatography (SFC) tandem mass spectrometry (MS/MS) and ultra-performance liquid chromatography (UPLC) MS/MS. C2 to C11 perfluoroalkyl carboxylic acids (PFCAs) were detected continuously in the ice core and their fluxes ranged from 2.5 to 8200 ng m-2 yr-1 (9.51-16,500 pg L-1). Trifluoroacetic acid (TFA) represented 71 % of the total mass of C2 - C11 PFCAs in the ice core and had increasing temporal trends in deposition. The distribution profile of PFCAs suggested that FTOHs were likely the atmospheric precursor to C8 - C11 PFCAs, whereas C2 - C6 PFCAs had alternative sources, such as HFCs and other CFC replacement compounds. Perfluorooctanesulfonic acid (PFOS) was also widely detected in 82 % of ice core subsections, and its isomer profile (81 % linear) indicated an electrochemical fluorination manufacturing source. Comparisons of PFAS concentrations with a marine aerosol proxy showed that marine aerosols were insignificant for the deposition of PFAS on Lomonosovfonna. Comparisons with a melt proxy showed that TFA and PFOS were mobile during meltwater percolation. This indicates that seasonal snowmelt and runoff from post-industrial accumulation on glaciers could be a significant seasonal source of PFAS to ecosystems in Arctic fjords.
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Affiliation(s)
- William F Hartz
- Department of Earth Sciences, University of Oxford, South Parks Road, Oxford OX1 3AN, United Kingdom; Department of Arctic Geology, University Centre in Svalbard (UNIS), NO-9171, Longyearbyen, Svalbard, Norway.
| | - Maria K Björnsdotter
- Institute of Environmental Assessment and Water Research (IDAEA-CSIC), C/Jordi Girona, 18-26, 08034 Barcelona, Catalonia, Spain; Man-Technology-Environment Research Centre (MTM), Örebro University, SE-701 82 Örebro, Sweden
| | - Leo W Y Yeung
- Man-Technology-Environment Research Centre (MTM), Örebro University, SE-701 82 Örebro, Sweden
| | - Andrew Hodson
- Department of Arctic Geology, University Centre in Svalbard (UNIS), NO-9171, Longyearbyen, Svalbard, Norway; Department of Environmental Sciences, Western Norway University of Applied Sciences, NO-6851 Sogndal, Norway
| | - Elizabeth R Thomas
- Ice Dynamics and Paleoclimate, British Antarctic Survey, High Cross, Cambridge CB3 0ET, United Kingdom
| | - Jack D Humby
- Ice Dynamics and Paleoclimate, British Antarctic Survey, High Cross, Cambridge CB3 0ET, United Kingdom
| | - Chris Day
- Department of Earth Sciences, University of Oxford, South Parks Road, Oxford OX1 3AN, United Kingdom
| | - Ingrid Ericson Jogsten
- Man-Technology-Environment Research Centre (MTM), Örebro University, SE-701 82 Örebro, Sweden
| | - Anna Kärrman
- Man-Technology-Environment Research Centre (MTM), Örebro University, SE-701 82 Örebro, Sweden
| | - Roland Kallenborn
- Faculty of Chemistry, Biotechnology and Food Sciences (KBM), Norwegian University of Life Sciences (NMBU), NO-1432 Ås, Norway; Department of Arctic Technology, University Centre in Svalbard (UNIS), NO-9171, Longyearbyen, Svalbard, Norway
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5
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Western LM, Redington AL, Manning AJ, Trudinger CM, Hu L, Henne S, Fang X, Kuijpers LJM, Theodoridi C, Godwin DS, Arduini J, Dunse B, Engel A, Fraser PJ, Harth CM, Krummel PB, Maione M, Mühle J, O’Doherty S, Park H, Park S, Reimann S, Salameh PK, Say D, Schmidt R, Schuck T, Siso C, Stanley KM, Vimont I, Vollmer MK, Young D, Prinn RG, Weiss RF, Montzka SA, Rigby M. A renewed rise in global HCFC-141b emissions between 2017-2021. ATMOSPHERIC CHEMISTRY AND PHYSICS 2022; 22:9601-9616. [PMID: 39315358 PMCID: PMC11417968 DOI: 10.5194/acp-22-9601-2022] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 09/25/2024]
Abstract
Global emissions of the ozone-depleting gas HCFC-141b (1,1-dichloro-1-fluoroethane, CH3CCl2F) derived from measurements of atmospheric mole fractions increased between 2017 and 2021 despite a fall in reported production and consumption of HCFC-141b for dispersive uses. HCFC-141b is a controlled substance under the Montreal Protocol, and its phase-out is currently underway, after a peak in reported consumption and production in developing (Article 5) countries in 2013. If reported production and consumption are correct, our study suggests that the 2017-2021 rise is due to an increase in emissions from the bank when appliances containing HCFC-141b reach the end of their life, or from production of HCFC-141b not reported for dispersive uses. Regional emissions have been estimated between 2017-2020 for all regions where measurements have sufficient sensitivity to emissions. This includes the regions of northwestern Europe, east Asia, the United States and Australia, where emissions decreased by a total of 2.3 ± 4.6 Ggyr-1, compared to a mean global increase of 3.0 ± 1.2 Ggyr-1 over the same period. Collectively these regions only account for around 30% of global emissions in 2020. We are not able to pinpoint the source regions or specific activities responsible for the recent global emission rise.
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Affiliation(s)
- Luke M. Western
- Global Monitoring Laboratory, National Oceanic and Atmospheric Administration, Boulder, CO, USA
- School of Chemistry, University of Bristol, Bristol, UK
| | | | | | - Cathy M. Trudinger
- Climate Science Centre, CSIRO Oceans and Atmosphere, Aspendale, Victoria, Australia
| | - Lei Hu
- Global Monitoring Laboratory, National Oceanic and Atmospheric Administration, Boulder, CO, USA
- Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO, USA
| | - Stephan Henne
- Empa, Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, Switzerland
| | - Xuekun Fang
- College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | | | | | - David S. Godwin
- Stratospheric Protection Division, Environmental Protection Agency, Washington, DC, USA
| | - Jgor Arduini
- Department of Pure and Applied Sciences, University of Urbino, Urbino, Italy
| | - Bronwyn Dunse
- Climate Science Centre, CSIRO Oceans and Atmosphere, Aspendale, Victoria, Australia
| | - Andreas Engel
- Institute for Atmospheric and Environmental Science, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Paul J. Fraser
- Climate Science Centre, CSIRO Oceans and Atmosphere, Aspendale, Victoria, Australia
| | - Christina M. Harth
- Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA, USA
| | - Paul B. Krummel
- Climate Science Centre, CSIRO Oceans and Atmosphere, Aspendale, Victoria, Australia
| | - Michela Maione
- Department of Pure and Applied Sciences, University of Urbino, Urbino, Italy
| | - Jens Mühle
- Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA, USA
| | | | - Hyeri Park
- Department of Oceanography, Kyungpook National University, Daegu, Republic of Korea
| | - Sunyoung Park
- Department of Oceanography, Kyungpook National University, Daegu, Republic of Korea
| | - Stefan Reimann
- Empa, Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, Switzerland
| | - Peter K. Salameh
- Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA, USA
| | - Daniel Say
- School of Chemistry, University of Bristol, Bristol, UK
| | - Roland Schmidt
- Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA, USA
| | - Tanja Schuck
- Institute for Atmospheric and Environmental Science, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Carolina Siso
- Global Monitoring Laboratory, National Oceanic and Atmospheric Administration, Boulder, CO, USA
- Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO, USA
| | - Kieran M. Stanley
- Institute for Atmospheric and Environmental Science, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Isaac Vimont
- Global Monitoring Laboratory, National Oceanic and Atmospheric Administration, Boulder, CO, USA
- Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO, USA
| | - Martin K. Vollmer
- Empa, Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, Switzerland
| | - Dickon Young
- School of Chemistry, University of Bristol, Bristol, UK
| | - 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
| | - Stephen A. Montzka
- Global Monitoring Laboratory, National Oceanic and Atmospheric Administration, Boulder, CO, USA
| | - Matthew Rigby
- School of Chemistry, University of Bristol, Bristol, UK
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6
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Björnsdotter MK, Hartz WF, Kallenborn R, Ericson Jogsten I, Humby JD, Kärrman A, Yeung LWY. Levels and Seasonal Trends of C 1-C 4 Perfluoroalkyl Acids and the Discovery of Trifluoromethane Sulfonic Acid in Surface Snow in the Arctic. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:15853-15861. [PMID: 34779623 PMCID: PMC8655978 DOI: 10.1021/acs.est.1c04776] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Revised: 10/23/2021] [Accepted: 11/07/2021] [Indexed: 05/31/2023]
Abstract
C1-C4 perfluoroalkyl acids (PFAAs) are highly persistent chemicals that have been found in the environment. To date, much uncertainty still exists about their sources and fate. The importance of the atmospheric degradation of volatile precursors to C1-C4 PFAAs were investigated by studying their distribution and seasonal variation in remote Arctic locations. C1-C4 PFAAs were measured in surface snow on the island of Spitsbergen in the Norwegian Arctic during January-August 2019. Trifluoroacetic acid (TFA), perfluoropropanoic acid (PFPrA), perfluorobutanoic acid (PFBA), and trifluoromethane sulfonic acid (TFMS) were detected in most samples, including samples collected at locations presumably receiving PFAA input solely from long-range processes. The flux of TFA, PFPrA, PFBA, and TFMS per precipitation event was in the ranges of 22-1800, 0.79-16, 0.19-170, and 1.5-57 ng/m2, respectively. A positive correlation between the flux of TFA, PFPrA, and PFBA with downward short-wave solar radiation was observed. No correlation was observed between the flux of TFMS and solar radiation. These findings suggest that atmospheric transport of volatile precursors and their subsequent degradation plays a major role in the global distribution of C2-C4 perfluoroalkyl carboxylic acids and their consequential deposition in Arctic environments. The discovery of TFMS in surface snow at these remote Arctic locations suggests that TFMS is globally distributed. However, the transport mechanism to the Arctic environment remains unknown.
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Affiliation(s)
- Maria K. Björnsdotter
- Man-Technology-Environment
Research Centre (MTM), Örebro University, Örebro SE-701 82, Sweden
| | - William F. Hartz
- Department
of Earth Sciences, University of Oxford, South Parks Road, Oxford OX1 3AN, United Kingdom
- Department
of Arctic Geology, University Centre in
Svalbard (UNIS), Longyearbyen, Svalbard NO-9171, Norway
| | - Roland Kallenborn
- Faculty
of Chemistry, Biotechnology and Food Sciences (KBM), Norwegian University of Life Sciences (NMBU), Ås NO-1432, Norway
- Department
of Arctic Technology, University Centre
in Svalbard (UNIS), Longyearbyen, Svalbard NO-9171, Norway
| | - Ingrid Ericson Jogsten
- Man-Technology-Environment
Research Centre (MTM), Örebro University, Örebro SE-701 82, Sweden
| | - Jack D. Humby
- Ice Dynamics
and Paleoclimate, British Antarctic Survey, High Cross, Cambridge CB3 0ET, United
Kingdom
| | - Anna Kärrman
- Man-Technology-Environment
Research Centre (MTM), Örebro University, Örebro SE-701 82, Sweden
| | - Leo W. Y. Yeung
- Man-Technology-Environment
Research Centre (MTM), Örebro University, Örebro SE-701 82, Sweden
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7
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Flerlage H, Velders GJM, de Boer J. A review of bottom-up and top-down emission estimates of hydrofluorocarbons (HFCs) in different parts of the world. CHEMOSPHERE 2021; 283:131208. [PMID: 34153914 DOI: 10.1016/j.chemosphere.2021.131208] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Revised: 06/07/2021] [Accepted: 06/10/2021] [Indexed: 06/13/2023]
Abstract
Hydrofluorocarbons (HFCs) are widespread alternatives for the ozone-depleting substances chlorofluorocarbons and hydrochlorofluorocarbons. They are used mainly as refrigerants or as foam-blowing agents. HFCs do not deplete the ozone layer, but they are very potent greenhouse gases, already contributing to global warming. Since 2019 HFCs are regulated under the Kigali Amendment to the Montreal Protocol, which demands reliable emission estimates to monitor the phase-down. Quantification of emissions is performed with two methods: bottom-up from product inventories or data on chemical sales; or top-down, inferred from atmospheric measurements by inverse modelling or interspecies correlation. Here, we review and compare the two methods and give an overview of HFC emissions from different parts of the world. Emission estimates reported by the different methods vary considerably. HFC emissions of developed countries (Annex I) are reported to the United Nations Framework Convention on Climate Change. These bottom-up estimates add up to only half of global emissions estimated from atmospheric data. Several studies with regional top-down estimates have shown that this gap is not owed to large-scale underreporting of emissions from developed countries, but mostly due to emissions from developing countries (non-Annex I). China accounts for a large fraction of the emissions causing the gap, but not entirely. Bottom-up and top-down estimations of emissions from other developing countries that could identify other large emitters are largely unavailable. Especially South America, West-, Central- and East-Africa, India, the Arabian Peninsula and Northern Australia are not well covered by measurement stations that could provide atmospheric data for top-down estimates.
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Affiliation(s)
- Hannah Flerlage
- Vrije Universiteit, Department of Environment and Health, Faculty of Sciences, De Boelelaan 1085, 1081 HV, Amsterdam, the Netherlands.
| | - Guus J M Velders
- National Institute for Public Health and the Environment (RIVM), Bilthoven, the Netherlands; Institute for Marine and Atmospheric Research Utrecht (IMAU), Utrecht University, the Netherlands
| | - Jacob de Boer
- Vrije Universiteit, Department of Environment and Health, Faculty of Sciences, De Boelelaan 1085, 1081 HV, Amsterdam, the Netherlands
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8
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Abstract
Chlorodifluoromethane (R-22), the most abundant freon in the atmosphere, was subjected to successful hydrodechlorination in the presence of palladium supported on γ-alumina, at a relatively low reaction temperature (180 °C). The combination of catalytic actions of alumina (performing freon dismutation) and Pd nanoparticles (catalyzing C–Cl bond splitting in the presence of hydrogen) results in the transformation of freon into valuable, chlorine-free products: methane and fluoroform, the mixture of which is used in plasma etching of silicon and silicon nitride. Very highly metal dispersed Pt/Al2O3 catalysts, with metal particles of ~1.3 nm in size, are not as effective as Pd/Al2O3, resulting in only partial dechlorination. A long-term dechlorination screening (3–4 days) showed good catalytic stability of Pd/alumina catalysts.
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9
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Chlorodifluoromethane Hydrodechlorination on Carbon-Supported Pd-Pt Catalysts. Beneficial Effect of Catalyst Oxidation. Catalysts 2021. [DOI: 10.3390/catal11050525] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Previously tested 2 wt % palladium-platinum catalysts supported on Norit activated carbon preheated to 1600 °C have been reinvestigated in CHFCl2 hydrodechlorination. An additionally adopted catalyst oxidation at 350–400 °C produced nearly an order of magnitude increase in the turnover frequency of Pd/C, from 4.1 × 10−4 to 2.63 × 10−3 s−1. This increase is not caused by changes in metal dispersion or possible decontamination of the Pd surface from superficial carbon, but rather by unlocking the active surface, originally inaccessible in metal particles tightly packed in the pores of carbon. Burning carbon from the pore walls attached to the metal changes the pore structure, providing easier access for the reactants to the entire palladium surface. Calcination of Pt/C and Pd-Pt/C catalysts results in much smaller evolution of catalytic activity than that observed for Pd/C. This shapes the relationship between turnover frequency (TOF) and alloy composition, which now does not confirm the Pd-Pt synergy invoked in the previous work. The absence of this synergy is confirmed by gradual regular changes in product selectivity, from 70 to 80% towards CH2F2 for Pd/C to almost 60% towards CH4 for Pt/C. The use of even higher-preheated carbon (1800 °C), completely free of micropores, results in a Pd/C catalyst that does not need to be oxidized to achieve high activity and excellent selectivity to CH2F2 (>90%).
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10
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Jani T, Yadav H, Prajapati D, Vinodkumar P, Vinodkumar M. Theoretical investigation of electron impact on formyl fluoride (HFCO). Radiat Phys Chem Oxf Engl 1993 2020. [DOI: 10.1016/j.radphyschem.2020.109098] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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11
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Hydrodechlorination of CHClF2 (HCFC-22) over Pd–Pt Catalysts Supported on Thermally Modified Activated Carbon. Catalysts 2020. [DOI: 10.3390/catal10111291] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Commercial activated carbon, pretreated in helium at 1600 °C and largely free of micropores, was used as a support for two series of 2 wt.% Pd–Pt catalysts, prepared by impregnating the support with metal acetylacetonates or metal chlorides. The catalysts were characterized by temperature-programmed methods, H2 chemisorption, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and scanning transmission electron microscopy (STEM) with energy dispersive spectroscopy (EDS). Overall, the results confirmed the existence of well-dispersed Pd–Pt nanoparticles in the bimetallic catalysts, ranging in size from 2 to 3 nm. The catalysts were investigated in the gas phase hydrodechlorination of chlorodifluoromethane (HCFC-22). In this environmentally relevant reaction, both the ex-chloride and ex-acetylacetonate Pd–Pt/C catalysts exhibited better hydrodechlorination activity than the monometallic catalysts, which is consistent with the previous results of hydrodechlorination for other chlorine-containing compounds. This synergistic effect can be attributed to the electron charge transfer from platinum to palladium. In general, product selectivity changes regularly with Pd–Pt alloy composition, from high in CH2F2 for Pd/C (70–80%) to the selective formation of CH4 for Pt/C (60–70%).
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12
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Yang F, Chu Q, Liu Q, Duan Y, Yang Z. The cubic-plus-association equation of state for hydrofluorocarbons, hydrofluoroolefins, and their binary mixtures. Chem Eng Sci 2019. [DOI: 10.1016/j.ces.2019.115182] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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13
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Zhang L, Long B. Hydrolysis of Formyl Fluoride Catalyzed by Sulfuric Acid and Formic Acid in the Atmosphere. ACS OMEGA 2019; 4:18996-19004. [PMID: 31763521 PMCID: PMC6868600 DOI: 10.1021/acsomega.9b01864] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2019] [Accepted: 10/24/2019] [Indexed: 05/31/2023]
Abstract
Formyl fluoride (HFCO) is an important atmospheric molecule, and its reaction with the OH radical is an important pathway when degradation of HFCO is considered in earth's troposphere. Here, we study the hydrolysis of formyl fluoride (HFCO + H2O) with sulfuric acid (H2SO4) and formic acid (HCOOH) acting as catalysts by utilizing M06-2X, CCSD(T)-F12a, and conventional transitional state theory with Eckart tunneling to explore the atmospheric impact of the above-said hydrolysis reactions. Our calculated results show that H2SO4 has a remarkably catalytic role in the gas-phase hydrolysis of HFCO, as the energy barriers of the HFCO + H2O reaction are reduced from 39.22 and 41.19 to 0.26 and -0.63 kcal/mol with respect to the separate reactants, respectively. In addition, we also find that H2SO4 can significantly accelerate the decomposition of FCH(OH)2 into hydrogen fluoride (HF) and HCOOH. This is because while the barrier height for the unimolecular decomposition of FCH(OH)2 into HF and HCOOH is 31.63 kcal/mol, the barrier height for the FCH(OH)2 + H2SO4 reaction is predicted to be -5.99 kcal/mol with respect to separate reactants. Nevertheless, the comparative relative rate analysis shows that the reaction between HFCO and the OH radical is still the most dominant pathway when the tropospheric degradation of HFCO is taken into account and that the gas-phase hydrolysis of HFCO may only occur with the help of H2SO4 when the atmospheric concentration of OH is about 101 molecules cm-3 or less. Having an understanding from the present study that the gas-phase hydrolysis of HFCO in the presence of H2SO4 has very limited role possibly in the absence of sunlight, we also prefer here to emphasize that the HFCO + H2O + H2SO4 reaction may occur on the surface of secondary organic aerosols for the formation of HCOOH.
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Affiliation(s)
- Lin Zhang
- Department
of Physics, Guizhou University, Guiyang 550025, China
| | - Bo Long
- Department
of Physics, Guizhou University, Guiyang 550025, China
- College
of Materials Science and Engineering, Guizhou
Minzu University, Guiyang 550025, China
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14
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Rivela CB, Tovar CM, Gibilisco R, Teruel MA, Barnes I, Wiesen P, Blanco MB. Product distribution and mechanism of the OH− initiated tropospheric degradation of three CFC replacement candidates: CH3CFCH2, (CF3)2CCH2 and (E/Z)-CF3CFCHF. RSC Adv 2019; 9:5592-5598. [PMID: 35515909 PMCID: PMC9060772 DOI: 10.1039/c8ra09627a] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2018] [Accepted: 02/03/2019] [Indexed: 11/21/2022] Open
Abstract
The OH initiated degradation of 2-fluoropropene, 3,3,3-trifluoro-2-(tri-fluoromethyl)propene and (E/Z)-1,2,3,3,3-pentafluoropropene has been investigated using a 1080 L chamber at 298 K and 1000 mbar of air coupled with in situ FTIR spectroscopy.
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Affiliation(s)
- Cynthia B. Rivela
- Instituto de Investigaciones en Fisicoquímica de Córdoba (I.N.F.I.Q.C.)
- CONICET
- Dpto. de Fisicoquímica
- Facultad de Ciencias Químicas
- Universidad Nacional de Córdoba
| | - Carmen M. Tovar
- Physikalische Chemie/FBC
- Bergische Universitaet Wuppertal
- Wuppertal
- Germany
| | - Rodrigo Gibilisco
- Physikalische Chemie/FBC
- Bergische Universitaet Wuppertal
- Wuppertal
- Germany
| | - Mariano A. Teruel
- Instituto de Investigaciones en Fisicoquímica de Córdoba (I.N.F.I.Q.C.)
- CONICET
- Dpto. de Fisicoquímica
- Facultad de Ciencias Químicas
- Universidad Nacional de Córdoba
| | - Ian Barnes
- Physikalische Chemie/FBC
- Bergische Universitaet Wuppertal
- Wuppertal
- Germany
| | - Peter Wiesen
- Physikalische Chemie/FBC
- Bergische Universitaet Wuppertal
- Wuppertal
- Germany
| | - María B. Blanco
- Instituto de Investigaciones en Fisicoquímica de Córdoba (I.N.F.I.Q.C.)
- CONICET
- Dpto. de Fisicoquímica
- Facultad de Ciencias Químicas
- Universidad Nacional de Córdoba
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15
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Li S, Park S, Lee JY, Ha KJ, Park MK, Jo CO, Oh H, Mühle J, Kim KR, Montzka SA, O'Doherty S, Krummel PB, Atlas E, Miller BR, Moore F, Weiss RF, Wofsy SC. Chemical evidence of inter-hemispheric air mass intrusion into the Northern Hemisphere mid-latitudes. Sci Rep 2018; 8:4669. [PMID: 29549350 PMCID: PMC5856755 DOI: 10.1038/s41598-018-22266-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Accepted: 02/20/2018] [Indexed: 11/12/2022] Open
Abstract
The East Asian Summer Monsoon driven by temperature and moisture gradients between the Asian continent and the Pacific Ocean, leads to approximately 50% of the annual rainfall in the region across 20–40°N. Due to its increasing scientific and social importance, there have been several previous studies on identification of moisture sources for summer monsoon rainfall over East Asia mainly using Lagrangian or Eulerian atmospheric water vapor models. The major source regions for EASM previously proposed include the North Indian Ocean, South China Sea and North western Pacific. Based on high-precision and high-frequency 6-year measurement records of hydrofluorocarbons (HFCs), here we report a direct evidence of rapid intrusion of warm and moist tropical air mass from the Southern Hemisphere (SH) reaching within a couple of days up to 33°N into East Asia. We further suggest that the combination of direct chemical tracer record and a back-trajectory model with physical meteorological variables helps pave the way to identify moisture sources for monsoon rainfall. A case study for Gosan station (33.25°N, 126.19°E) indicates that the meridional transport of precipitable water from the SH accompanying the southerly/southwesterly flow contributes most significantly to its summer rainfall.
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Affiliation(s)
- S Li
- Kyungpook Institute of Oceanography, College of Natural Sciences, Kyungpook National University, Daegu, South Korea
| | - S Park
- Kyungpook Institute of Oceanography, College of Natural Sciences, Kyungpook National University, Daegu, South Korea. .,Department of Oceanography, School of Earth System Sciences, Kyungpook National University, Daegu, South Korea.
| | - J-Y Lee
- Center for Climate Physics, Institute for Basic Science, Busan, South Korea.,Research Center for Climate Sciences, Pusan National University, Busan, South Korea
| | - K-J Ha
- Center for Climate Physics, Institute for Basic Science, Busan, South Korea.,Department of Atmospheric Sciences, Pusan National University, Busan, South Korea
| | - M-K Park
- Kyungpook Institute of Oceanography, College of Natural Sciences, Kyungpook National University, Daegu, South Korea
| | - C O Jo
- Kyungpook Institute of Oceanography, College of Natural Sciences, Kyungpook National University, Daegu, South Korea
| | - H Oh
- Center for Climate Physics, Institute for Basic Science, Busan, South Korea.,Department of Atmospheric Sciences, Pusan National University, Busan, South Korea
| | - J Mühle
- Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA, USA
| | - K-R Kim
- GIST College, Gwangju Institute of Science and Technology, Gwangju, South Korea
| | - S A Montzka
- Earth System Research Laboratory, NOAA, Boulder, CO, USA
| | - S O'Doherty
- School of Chemistry, University of Bristol, Bristol, UK
| | - P B Krummel
- Climate Science Centre, CSIRO Oceans and Atmosphere, Aspendale, Victoria, Australia
| | - E Atlas
- Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, USA
| | - B R Miller
- Earth System Research Laboratory, NOAA, Boulder, CO, USA.,Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, Colorado, USA
| | - F Moore
- Earth System Research Laboratory, NOAA, Boulder, CO, USA.,Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, Colorado, USA
| | - R F Weiss
- Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA, USA
| | - S C Wofsy
- School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
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16
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Detecting recovery of the stratospheric ozone layer. Nature 2018; 549:211-218. [PMID: 28905899 DOI: 10.1038/nature23681] [Citation(s) in RCA: 134] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Accepted: 07/31/2017] [Indexed: 11/09/2022]
Abstract
As a result of the 1987 Montreal Protocol and its amendments, the atmospheric loading of anthropogenic ozone-depleting substances is decreasing. Accordingly, the stratospheric ozone layer is expected to recover. However, short data records and atmospheric variability confound the search for early signs of recovery, and climate change is masking ozone recovery from ozone-depleting substances in some regions and will increasingly affect the extent of recovery. Here we discuss the nature and timescales of ozone recovery, and explore the extent to which it can be currently detected in different atmospheric regions.
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17
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Liang Q, Chipperfield MP, Fleming EL, Abraham NL, Braesicke P, Burkholder JB, Daniel JS, Dhomse S, Fraser PJ, Hardiman SC, Jackman CH, Kinnison DE, Krummel PB, Montzka SA, Morgenstern O, McCulloch A, Mühle J, Newman PA, Orkin VL, Pitari G, Prinn RG, Rigby M, Rozanov E, Stenke A, Tummon F, Velders GJM, Visioni D, Weiss RF. Deriving Global OH Abundance and Atmospheric Lifetimes for Long-Lived Gases: A Search for CH 3CCl 3 Alternatives. JOURNAL OF GEOPHYSICAL RESEARCH. ATMOSPHERES : JGR 2017; 122:11914-11933. [PMID: 38515436 PMCID: PMC10956888 DOI: 10.1002/2017jd026926] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/23/2024]
Abstract
An accurate estimate of global hydroxyl radical (OH) abundance is important for projections of air quality, climate, and stratospheric ozone recovery. As the atmospheric mixing ratios of methyl chloroform (CH3CCl3) (MCF), the commonly used OH reference gas, approaches zero, it is important to find alternative approaches to infer atmospheric OH abundance and variability. The lack of global bottom-up emission inventories is the primary obstacle in choosing a MCF alternative. We illustrate that global emissions of long-lived trace gases can be inferred from their observed mixing ratio differences between the Northern Hemisphere (NH) and Southern Hemisphere (SH), given realistic estimates of their NH-SH exchange time, the emission partitioning between the two hemispheres, and the NH versus SH OH abundance ratio. Using the observed long-term trend and emissions derived from the measured hemispheric gradient, the combination of HFC-32 (CH2F2), HFC-134a (CH2FCF3, HFC-152a (CH3CHF2), and HCFC-22 (CHClF2), instead of a single gas, will be useful as a MCF alternative to infer global and hemispheric OH abundance and trace gas lifetimes. The primary assumption on which this multispecies approach relies is that the OH lifetimes can be estimated by scaling the thermal reaction rates of a reference gas at 272 K on global and hemispheric scales. Thus, the derived hemispheric and global OH estimates are forced to reconcile the observed trends and gradient for all four compounds simultaneously. However, currently, observations of these gases from the surface networks do not provide more accurate OH abundance estimate than that from MCF.
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Affiliation(s)
- Qing Liang
- Atmospheric Chemistry and Dynamics Laboratory, NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
- Universities Space Research Association, GESTAR, Columbia, Maryland, USA
| | - Martyn P Chipperfield
- National Centre for Earth Observation, School of Earth and Environment, University of Leeds, Leeds, UK
| | - Eric L Fleming
- Atmospheric Chemistry and Dynamics Laboratory, NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
- Science Systems and Applications, Inc, Lanham, Maryland, USA
| | - N Luke Abraham
- National Centre for Atmospheric Science, Leeds, UK
- Department of Chemistry, University of Cambridge, Cambridge, UK
| | | | - James B Burkholder
- Chemical Sciences Division, NOAA Earth System Research Laboratory, Boulder, Colorado, USA
| | - John S Daniel
- Chemical Sciences Division, NOAA Earth System Research Laboratory, Boulder, Colorado, USA
| | - Sandip Dhomse
- National Centre for Earth Observation, School of Earth and Environment, University of Leeds, Leeds, UK
| | - Paul J Fraser
- Climate Science Centre, CSIRO Oceans and Atmosphere, Aspendale, Vic, Australia
| | | | - Charles H Jackman
- Atmospheric Chemistry and Dynamics Laboratory, NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
| | | | - Paul B Krummel
- Climate Science Centre, CSIRO Oceans and Atmosphere, Aspendale, Vic, Australia
| | - Stephen A Montzka
- Global Monitoring Division, NOAA Earth System Research Laboratory, Boulder, Colorado, USA
| | - Olaf Morgenstern
- National Institute of Water and Atmospheric Research, Wellington, New Zealand
| | | | - Jens Mühle
- Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California, USA
| | - Paul A Newman
- Atmospheric Chemistry and Dynamics Laboratory, NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
| | - Vladimir L Orkin
- National Institute of Standards and Technology, Gaithersburg, Maryland, USA
| | - Giovanni Pitari
- Department of Physical and Chemical Sciences, Università dell'Aquila, L'Aquila, Italy
| | - Ronald G Prinn
- Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Matthew Rigby
- School of Chemistry, University of Bristol, Bristol, UK
| | - Eugene Rozanov
- Institute for Atmospheric and Climate Science, ETH Zurich, Zurich, Switzerland
- Physikalisch-Meteorologisches Observatorium Davos World Radiation Centre, Davos Dorf, Switzerland
| | - Andrea Stenke
- Institute for Atmospheric and Climate Science, ETH Zurich, Zurich, Switzerland
| | - Fiona Tummon
- Institute for Atmospheric and Climate Science, ETH Zurich, Zurich, Switzerland
| | - Guus J M Velders
- National Institute for Public Health and the Environment, Bilthoven, Netherlands
- Institute for Marine and Atmospheric Research, Utrecht University, Utrecht, Netherlands
| | - Daniele Visioni
- Department of Physical and Chemical Sciences, Università dell'Aquila, L'Aquila, Italy
| | - Ray F Weiss
- Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California, USA
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18
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MacInnis JJ, French K, Muir DCG, Spencer C, Criscitiello A, De Silva AO, Young CJ. Emerging investigator series: a 14-year depositional ice record of perfluoroalkyl substances in the High Arctic. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2017; 19:22-30. [PMID: 28092384 DOI: 10.1039/c6em00593d] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
To improve understanding of long-range transport of perfluoroalkyl substances to the High Arctic, samples were collected from a snow pit on the Devon Ice Cap in spring 2008. Snow was analyzed for perfluoroalkyl acids (PFAAs), including perfluoroalkyl carboxylic acids (PFCAs) and perfluoroalkyl sulfonic acids (PFSAs), as well as perfluorooctane sulfonamide (FOSA). PFAAs were detected in all samples dated from 1993 to 2007. PFAA fluxes ranged from <1 to hundreds of ng per m2 per year. Flux ratios of even-odd PFCA homologues were mostly between 0.5 and 2, corresponding to molar ratios expected from atmospheric oxidation of fluorotelomer compounds. Concentrations of perfluorobutanoic acid (PFBA) were much higher than other PFCAs, suggesting PFBA loading on the Devon Ice Cap is influenced by additional sources, such as the oxidation of heat transfer fluids. All PFCA fluxes increased with time, while PFSA fluxes generally decreased with time. No correlations were observed between PFAAs and the marine aerosol tracer, sodium. Perfluoro-4-ethylcyclohexanesulfonate (PFECHS) was detected for the first time in an atmospherically - derived sample, and its presence may be attributed to aircraft hydraulic system leakage. Observations of PFAAs from these samples provide further evidence that atmospheric oxidation of volatile precursors is an important source of PFAAs to the Arctic environment.
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Affiliation(s)
- John J MacInnis
- Department of Chemistry, Memorial University, St. John's, NL, Canada A1B 3X7.
| | - Katherine French
- Aquatic Contaminants Research Division, Environment and Climate Change Canada, Burlington, ON, Canada L7S 1A1.
| | - Derek C G Muir
- Aquatic Contaminants Research Division, Environment and Climate Change Canada, Burlington, ON, Canada L7S 1A1.
| | - Christine Spencer
- Aquatic Contaminants Research Division, Environment and Climate Change Canada, Burlington, ON, Canada L7S 1A1.
| | | | - Amila O De Silva
- Aquatic Contaminants Research Division, Environment and Climate Change Canada, Burlington, ON, Canada L7S 1A1.
| | - Cora J Young
- Department of Chemistry, Memorial University, St. John's, NL, Canada A1B 3X7.
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19
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Goel H, Butler CL, Windom ZW, Rai N. Vapor Liquid Equilibria of Hydrofluorocarbons Using Dispersion-Corrected and Nonlocal Density Functionals. J Chem Theory Comput 2016; 12:3295-304. [PMID: 27295451 DOI: 10.1021/acs.jctc.6b00305] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Recent developments in dispersion corrected and nonlocal density functionals are aimed at accurately capturing dispersion interactions, a key shortcoming of local and semilocal approximations of density functional theory. These functionals have shown significant promise for dimers and small clusters of molecules as well as crystalline materials. However, their efficacy for predicting vapor liquid equilibria is largely unexplored. In this work, we examine the accuracy of dispersion-corrected and nonlocal van der Waals functionals by computing the vapor liquid coexistence curves (VLCCs) of hydrofluoromethanes. Our results indicate that the PBE-D3 functional performs significantly better in predicting saturated liquid densities than the rVV10 functional. With the PBE-D3 functional, we also find that as the number of fluorine atoms increase in the molecule, the accuracy of saturated liquid density prediction improves as well. All the functionals significantly underpredict the saturated vapor densities, which also result in an underprediction of saturated vapor pressure of all compounds. Despite the differences in the bulk liquid densities, the local microstructures of the liquid CFH3 and CF2H2 are relatively insensitive to the density functional employed. For CF3H, however, rVV10 predicts slightly more structured liquid than the PBE-D3 functional.
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Affiliation(s)
- Himanshu Goel
- Dave C. Swalm School of Chemical Engineering and Center for Advanced Vehicular Systems, Mississippi State University , Mississippi State 39762, Mississippi, United States
| | - Charles L Butler
- Dave C. Swalm School of Chemical Engineering and Center for Advanced Vehicular Systems, Mississippi State University , Mississippi State 39762, Mississippi, United States.,East Mississippi Community College, Scooba 39358, Mississippi, United States
| | - Zachary W Windom
- Dave C. Swalm School of Chemical Engineering and Center for Advanced Vehicular Systems, Mississippi State University , Mississippi State 39762, Mississippi, United States
| | - Neeraj Rai
- Dave C. Swalm School of Chemical Engineering and Center for Advanced Vehicular Systems, Mississippi State University , Mississippi State 39762, Mississippi, United States
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20
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Ou-Yang CF, Chang CC, Chen SP, Chew C, Lee BR, Chang CY, Montzka SA, Dutton GS, Butler JH, Elkins JW, Wang JL. Changes in the levels and variability of halocarbons and the compliance with the Montreal Protocol from an urban view. CHEMOSPHERE 2015; 138:438-446. [PMID: 26160300 DOI: 10.1016/j.chemosphere.2015.06.070] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2015] [Revised: 06/15/2015] [Accepted: 06/22/2015] [Indexed: 06/04/2023]
Abstract
Ambient levels and variability of major atmospheric halocarbons, i.e. CFC-12, CFC-11, CFC-113, CCl4, CH3CCl3, C2HCl3, and C2Cl4 in a major metropolis (Taipei, Taiwan) were re-investigated after fourteen years by flask sampling in 2012. Our data indicates that the variability expressed as standard deviations (SD) of CFC-113 and CCl4 remained small (2.0 ppt and 1.9 ppt, respectively) for the 10th-90th percentile range in both sampling periods; whereas the variability of CFC-12, CFC-11, C2HCl3, and C2Cl4 measured in 2012 became noticeably smaller than observed in 1998, suggesting their emissions were reduced over time. By comparing with the background data of a global network (NOAA/ESRL/GMD baseline observatories), the ambient levels and distribution of these major halocarbons in Taipei approximated those at a background site (Mauna Loa) in 2012, suggesting that the fingerprint of the major halocarbons in a used-to-be prominent source area has gradually approached to that of the background atmosphere.
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Affiliation(s)
- Chang-Feng Ou-Yang
- Department of Chemistry, National Central University, Taoyuan 32001, Taiwan; Department of Atmospheric Sciences, National Central University, Taoyuan 32001, Taiwan
| | - Chih-Chung Chang
- Research Center for Environmental Changes, Academia Sinica, Taipei 11529, Taiwan.
| | - Shen-Po Chen
- Department of Chemistry, National Central University, Taoyuan 32001, Taiwan
| | - Clock Chew
- Research Center for Environmental Changes, Academia Sinica, Taipei 11529, Taiwan
| | - Bo-Ru Lee
- Research Center for Environmental Changes, Academia Sinica, Taipei 11529, Taiwan
| | - Chih-Yuan Chang
- Research Center for Environmental Changes, Academia Sinica, Taipei 11529, Taiwan
| | - Stephen A Montzka
- Global Monitoring Division, Earth Systems Research Laboratory, National Oceanic and Atmospheric Administration, Boulder, CO 80305, United States
| | - Geoffrey S Dutton
- Global Monitoring Division, Earth Systems Research Laboratory, National Oceanic and Atmospheric Administration, Boulder, CO 80305, United States; Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80309, United States
| | - James H Butler
- Global Monitoring Division, Earth Systems Research Laboratory, National Oceanic and Atmospheric Administration, Boulder, CO 80305, United States
| | - James W Elkins
- Global Monitoring Division, Earth Systems Research Laboratory, National Oceanic and Atmospheric Administration, Boulder, CO 80305, United States
| | - Jia-Lin Wang
- Department of Chemistry, National Central University, Taoyuan 32001, Taiwan.
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