On the ability of proglacial lake diatoms to reconstruct Antarctic past ozone changes

Observations on the decline of Antarctic stratospheric ozone concentrations since the 1980s and its subsequent recovery have gained attention from both society and the scientific community. One of the major concerns associated with ozone depletion is the increased amount of UV radiation reaching the Earth's surface, which in turn negatively impacts the environment and the organisms inhabiting it. Considering its potential impacts on the (sub)polar ecosystems and biogeochemical processes, assessing its past changes while accounting for both natural and anthropogenic drivers is essential to understanding the stratospheric ozone concentration history in Antarctica. In this work, we explore the use of diatom taxa in dated proglacial lake sediment profiles from Antarctica as potential proxies for ozone variability. Diatoms are sensitive to changes in the lake environment and water column conditions. Core-top sediment layers, dated by ²¹⁰ Pb excess, allowed the identification of diatom assemblages from time periods corresponding to the ozone data measured at the Faraday/Vernadsky Station. From this approach, a diatom assemblage composed of Gomphonema sp., Nitzschia cf. kleinteichiana, Humidophila tabellariaeformis , and Pinnularia borealis showed a significant regression with the ozone data, allowing the development of a reconstruction model for the modern epoch (1911 to 2011). The method was applied to a Holocene lake from the same ice-free area in Antarctica, resulting in a reconstruction dated back to 7714 cal yr BP.