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https://doi.org/10.5194/egusphere-2024-560
https://doi.org/10.5194/egusphere-2024-560
12 Mar 2024
 | 12 Mar 2024

On the atmospheric budget of ethylene dichloride and its impact on stratospheric chlorine and ozone (2002–2020)

Ryan Hossaini, David Sherry, Zihao Wang, Martyn Chipperfield, Wuhu Feng, David Oram, Karina Adcock, Stephen Montzka, Isobel Simpson, Andrea Mazzeo, Amber Leeson, Elliot Atlas, and Charles C.-K. Chou

Abstract. Ethylene dichloride (EDC), or 1-2-dichloroethane, is an industrial very short-lived substance (VSLS) whose major use is as a feedstock in the production chain of polyvinyl chloride (PVC). Like other chlorinated VSLS, transport of EDC (or its atmospheric oxidation products) to the stratosphere could contribute to ozone depletion there. However, despite annual production volumes greatly exceeding those of more prominent VSLS (e.g. dichloromethane), global EDC observations are sparse, thus the magnitude and distribution of EDC emissions and trends in its atmospheric abundance are poorly known. In this study we performed an exploratory analysis of the global EDC budget between 2002 and 2020. Combining bottom-up data on annual production and assumptions around fugitive losses during production and feedstock use, we assessed the EDC source strength required to reproduce atmospheric EDC observations. We show that the TOMCAT/SLIMCAT 3-D chemical transport model (CTM) reproduces EDC measurements from various aircraft missions well, including HIPPO (2009–2011), ATom (2016–2018) and KORUS-AQ (2016), along with surface measurements from South East Asia, when assuming a regionally varying production emission factor in the range 0.5–1.5 %. Our findings imply substantial fugitive losses of EDC and/or substantial emissive applications (e.g. solvent use) that are poorly reported. We estimate EDC’s global source increased by ~45 % between 2002 (349±61 Gg/yr) and 2020 (505±90 Gg/yr) with its contribution to stratospheric chlorine increasing from 8.2 (±1.5) ppt Cl to ~12.9 (±2.4) ppt Cl over this period. EDC’s relatively short overall tropospheric lifetime (~83 days) limits, though does not preclude, its transport to the stratosphere and we show that its impact on ozone is small at present. Annually averaged, EDC is estimated to have decreased ozone in the lower stratosphere by up to several ppb (<1 %) in 2020, though a larger effect in the springtime Southern Hemisphere polar lower stratosphere is apparent (decreases of up to ~1.3 %). Given strong potential for growth in EDC production tied to demand for PVC, ongoing measurements would be of benefit to monitor potential future increases in its atmospheric abundance and its contribution to ozone depletion.

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Ryan Hossaini, David Sherry, Zihao Wang, Martyn Chipperfield, Wuhu Feng, David Oram, Karina Adcock, Stephen Montzka, Isobel Simpson, Andrea Mazzeo, Amber Leeson, Elliot Atlas, and Charles C.-K. Chou

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2024-560', Anonymous Referee #1, 04 Apr 2024
  • RC2: 'Review of the manuscript “On the atmospheric budget of ethylene dichloride and its impact on stratospheric chlorine and ozone (2002-2020)” by Hossaini et al., 2024.', Rafael Pedro Fernandez, 23 Apr 2024
Ryan Hossaini, David Sherry, Zihao Wang, Martyn Chipperfield, Wuhu Feng, David Oram, Karina Adcock, Stephen Montzka, Isobel Simpson, Andrea Mazzeo, Amber Leeson, Elliot Atlas, and Charles C.-K. Chou
Ryan Hossaini, David Sherry, Zihao Wang, Martyn Chipperfield, Wuhu Feng, David Oram, Karina Adcock, Stephen Montzka, Isobel Simpson, Andrea Mazzeo, Amber Leeson, Elliot Atlas, and Charles C.-K. Chou

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Short summary
Ethylene dichloride (EDC) is an industrial chemical used to produce polyvinyl chloride (PVC). We analysed EDC production data to estimate global EDC emissions (2002 to 2020). The emissions were included in an atmospheric model and evaluated by comparing simulated EDC to EDC measurements in the troposphere. We show EDC contributes ozone-depleting chlorine to the stratosphere and this has increased with increasing EDC emissions. EDC’s impact on stratospheric ozone is currently small, but non-zero.