Antarctic Study on Tropospheric Aerosol and Snow Chemistry (ASTASC) in JARE Phase X

The Tenth Symposium on Polar Science/Special session: [S] Future plan of Antarctic research: Towards phase X of the Japanese Antarctic Research Project (2022-2028) and beyond, Tue. 3 Dec. / Entrance Hall (1st floor) at National Institute of Polar Research (NIPR

Isotopic evidence for acidity-driven enhancement of sulfate formation after SO2 emission control

After the 1980s, atmospheric sulfate reduction is slower than the dramatic reductions in sulfur dioxide (SO2) emissions. However, a lack of observational evidence has hindered the identification of causal feedback mechanisms. Here, we report an increase in the oxygen isotopic composition of sulfate (Δ17OSO42-) in a Greenland ice core, implying an enhanced role of acidity-dependent in-cloud oxidation by ozone (up to 17 to 27 in sulfate production since the 1960s. A global chemical transport model reproduces the magnitude of the increase in observed Δ17OSO42- with a 10 to 15 to sulfate in Eastern North America and Western Europe. With an expected continued decrease in atmospheric acidity, this feedback will continue in the future and partially hinder air quality improvements

Homogeneous sulfur isotope signature in East Antarctica and implication for sulfur source shifts through the last glacial-interglacial cycle

International audienceSulfate aerosol (So 4 2−) preserved in Antarctic ice cores is discussed in the light of interactions between marine biological activity and climate since it is mainly sourced from biogenic emissions from the surface ocean and scatters solar radiation during traveling in the atmosphere. However, there has been a paradox between the ice core record and the marine sediment record; the former shows constant nonsea-salt (nss-) So 4 2− flux throughout the glacial-interglacial changes, and the latter shows a decrease in biogenic productivity during glacial periods compared to interglacial periods. Here, by ensuring the homogeneity of sulfur isotopic compositions of atmospheric nss-So 4 2− (δ 34 S nss) over East Antarctica, we established the applicability of the signature as a robust tool for distinguishing marine biogenic and nonmarine biogenic So 4 2−. Our findings, in conjunction with existing records of nss-SO 4 2− flux and δ 34 S nss in Antarctic ice cores, provide an estimate of the relative importance of marine biogenic So 4 2− during the last glacial period to be 48 ± 10% of nss-SO 4 2− , slightly lower than 59 ± 11% during the interglacial periods. Thus, our results tend to reconcile the ice core and sediment records, with both suggesting the decrease in marine productivity around Southern ocean under the cold climate