[A-CC37] [EJ] Ice cores and past environmental changes

[ACC37-P05] A 60-year record of atmospheric sulfate and nitrate depositions preserved in the high-accumulation dome ice core, South East Greenland

*Iizuka Yoshinori¹, Koji Fujita², Shohei Hattori³, Ryu Uemura⁴, Osamu Seki¹, Chihiro Miyamoto⁵, Toshitaka Suzuki⁶, Naohiro Yoshida^3,7, Hideaki Motoyama⁸, Sumito Matoba¹ (1.Institite of Low Temperature Science, Hokkaido University, 2.Graduate School of Environmental Studies, Nagoya University, 3.Department of Chemical Science and Engineering, School of Materials and Chemical Technology, Tokyo Institute of Technology, 4.Department of Chemistry, Biology, and Marine Science, Faculty of Science, University of the Ryukyus, 5.Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo, 6.Department of Earth and Environmental Sciences, Faculty of Science, Yamagata University, 7.Earth-Life Science Institute, Tokyo Institute of Technology, 8.National Institute of Polar Research)

Keywords:Greenland, ice core, sulfate ion, nitrate ion, Anthropogenic emission

Southeastern Greenland has a dome whose elevation is higher than 3000 m a.s.l. with high accumulation rate (about 1 m yr^-1) in water equivalent, which is suitable conditions for reconstructing past environmental changes with a high-time resolution. In this study, we measured major ion fluxes in 90 m ice core drilled from the SE-Dome region in 2015, and obtained records of annual ion fluxes from 1957 to 2014. High average NO₃^- flux (68.9 mg m^-2 yr^-1) with low δ¹⁵N value in the SE-Dome ice core suggests negligible effect of the post depositional NO₃^- loss. Thus, the SE-Dome region is one of the best locations for reconstructing nitrate fluxes. Decreasing trend of non-sea-salt (nss) SO₄^2- flux from 1970 to 2010 follows well that of anthropogenic SOx emission from North America, suggesting that the SO₄^2- flux in SE-Dome ice core mainly records anthropogenic emission of SOx from North America. In contrast, the decadal trend of NO₃^- flux in SE-Dome ice core differs from the decreasing trend of anthropogenic NOx emission in North America. The exact cause of the apparent non-linear relationship remains unclear but a formation of ammonium nitrate particles enhanced by SOx reduction appears to be an important mechanism as suggested by excess ammonium flux over sulfate. Our NO₃^- flux record is similar to other ice cores in Greenland high elevation sites on 5-yr running average, suggesting that NO₃^- concentrations records from these ice cores are reliable.