RESEARCH ARTICLE

South-hemispheric marine aerosol Hg and S isotope compositions reveal different oxidation pathways

¹ State Key Laboratory of Environmental GeochemistryInstitute of GeochemistryChinese Academy of Sciences, Guiyang 550081, China
² School of Earth System ScienceInstitute of Surface-Earth System ScienceTianjin University, Tianjin 300072, China
³ Joint International Research Laboratory of Atmospheric and Earth System SciencesSchool of Atmospheric SciencesNanjing University, Nanjing 210023, China
⁴ Key Laboratory of Geographic Information Science (Ministry of Education)School of Geographic Sciences and State Key Lab of Estuarine and Coastal ResearchEast China Normal University, Shanghai 200241, China
⁵ Polar Research Institute of China, Shanghai 200062, China
⁶ Géosciences Environnement ToulouseCNRS/IRD/Université Paul Sabatier Toulouse 3Toulouse, France
⁷ Laboratoire de Géochimie des Isotopes StablesInstitut de Physique du Globe de ParisUniversité Paris DiderotCNRS UMR 7154Sorbonne Paris-Cité1 rue de Jussieu, Paris 75005, France
⁸ School of Civil EngineeringTianjin University, Tianjin 300072, China

^* Corresponding authors (emails: auyangdavid@gmail.com (David AuYang); auyangdavid@gmail.com(Jiubin Chen))

Received: 4 October 2021
Accepted: 11 October 2021

Abstract

Particle-bound mercury (PBM) records the oxidation of elemental mercury, of which the main oxidation pathways (Br∙/Cl∙/OH∙/O₃) remain unclear, especially in the Southern Hemisphere. Here, we present latitudinal covariations of Hg and S-isotopic anomalies in cross-hemispheric marine aerosols that evidence an equator-to-poleward transition of Hg oxidants from OH∙/O₃ in tropics to Br∙/Cl∙ in polar regions highlighting thus the presence of distinct oxidation processes producing PBM. The correlations between Hg, S and O-isotopic compositions measured in PBM, sulfates and nitrates respectively within the aerosols highlight the implication of common oxidants in their formations at different latitudes. Our results open a new window to better quantify the present-day atmospheric Hg, S and N budgets and to evaluate the influences of aerosols on climate and ecosystems once the isotopic fractionations associated with each process have been determined.