Antarctic ozone hole modifies iodine geochemistry on the Antarctic Plateau

Andrea Spolaor,Kitae Kim,Rafael P Fernandez,Jean-François Lamarque,François Burgay,Carlo Barbante,Juan Pablo Corella,Carlos A Cuevas,Elena Barbaro,Douglas E Kinnison,Massimo Frezzotti,Clara Turetta,Paul Vallelonga,Fabrizio De Blasi,Alfonso Saiz-Lopez

doi:10.1038/s41467-021-26109-x

Abstract

Polar stratospheric ozone has decreased since the 1970s due to anthropogenic emissions of chlorofluorocarbons and halons, resulting in the formation of an ozone hole over Antarctica. The effects of the ozone hole and the associated increase in incoming UV radiation on terrestrial and marine ecosystems are well established; however, the impact on geochemical cycles of ice photoactive elements, such as iodine, remains mostly unexplored. Here, we present the first iodine record from the inner Antarctic Plateau (Dome C) that covers approximately the last 212 years (1800-2012 CE). Our results show that the iodine concentration in ice remained constant during the pre-ozone hole period (1800-1974 CE) but has declined twofold since the onset of the ozone hole era (~1975 CE), closely tracking the total ozone evolution over Antarctica. Based on ice core observations, laboratory measurements and chemistry-climate model simulations, we propose that the iodine decrease since ~1975 is caused by enhanced iodine re-emission from snowpack due to the ozone hole-driven increase in UV radiation reaching the Antarctic Plateau. These findings suggest the potential for ice core iodine records from the inner Antarctic Plateau to be as an archive for past stratospheric ozone trends.

Highlights

Polar stratospheric ozone has decreased since the 1970s due to anthropogenic emissions of chlorofluorocarbons and halons, resulting in the formation of an ozone hole over Antarctica
We report the first iodine record from an ice core collected at Dome C, covering the period of 1800–2012
Laboratory measurements and chemistry-climate model simulations, we find that the iodine concentration in ice remained relatively stable during the pre-ozone hole period (1800–1974) but has gradually declined by a factor of 2 since the onset of the Antarctic ozone hole in the mid-1970s

Summary

Introduction

Polar stratospheric ozone has decreased since the 1970s due to anthropogenic emissions of chlorofluorocarbons and halons, resulting in the formation of an ozone hole over Antarctica. To evaluate the hypothesis that the increased UV radiation reaching the Antarctic Plateau due to ozone hole formation has altered iodine concentrations within the ice core, we computed the total ozone column (TOC) and ozone hole evolution during the 1950–2010 period using the CAM-Chem chemistry-climate model[25,26] (see “Methods”).

Results

Conclusion