Anthropogenic Impacts on Tropospheric Reactive Chlorine Since the Preindustrial

• Published in: Geophysical Research Letters
• Main Authors: Zhai, Shuting, Wang, Xuan, Mcconnell, Joseph, R, Geng, Lei, Cole‐dai, Jihong, Sigl, Michael, Chellman, Nathan, Sherwen, Tomás, Pound, Ryan, Fujita, Koji, Hattori, Shohei, Moch, Jonathan, M, Zhu, Lei, Evans, Mat, Legrand, Michel, Liu, Pengfei, Pasteris, Daniel, Chan, Yuk‐chun, Murray, Lee, T, Alexander, Becky
• Other Authors: Laboratoire Interuniversitaire des Systèmes Atmosphériques (LISA (UMR_7583)), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2021
• Subjects: [SDE]Environmental Sciences; Greenland; Greenland ice core; ice core
• Online Access: https://hal.science/hal-04278530; https://hal.science/hal-04278530/document; https://hal.science/hal-04278530/file/Zhai_et_al_2021GL093808.pdf; https://doi.org/10.1029/2021GL093808

Abstract Tropospheric reactive gaseous chlorine (Cl y ) impacts the atmosphere's oxidation capacity with implications for chemically reduced gases such as methane. Here we use Greenland ice‐core records of chlorine, sodium, and acidity, and global model simulations to show how tropospheric Cl y has been impacted by anthropogenic emissions since the 1940s. We show that anthropogenic contribution of nonsea‐salt chlorine significantly influenced total chlorine and its trends after the 1940s. The modeled regional 170% Cl y increase from preindustrial to the 1970s was driven by acid displacement from sea‐salt‐aerosol, direct emission of hydrochloric acid (HCl) from combustion, and chemical reactions driven by anthropogenic nitrogen oxide (NO x ) emissions. Since the 1970s, the modeled 6% Cl y decrease was caused mainly by reduced anthropogenic HCl emissions from air pollution mitigation policies. Our findings suggest that anthropogenic emissions of acidic gases and their emission control strategies have substantial impacts on Cl y with implications for tropospheric oxidants, methane, and mercury.