[ACC37-P06] The triple isotopic composition of oxygen for sulfate and nitrate in surface snow in a latudinal transect in East Antarcica
Keywords:stable isotope, triple oxygen isotopes, sulfate, nitrate
In order to test spatial variation of isotopic compositions, especially for the difference in Δ17O values between coastal site and inland site, here we present latitudinal variation of Δ17O value and conventional isotopic compositions (δ34S, δ15N, and δ18O) of SO42- and NO3- in surface snow in eastern Dronning Maud Land, East Antarctica. Snow samples were collected from the surface at low- and high-elevation sites during the 54th and 57 th Japanese Antarctic Research, respectively. Δ17O values of non-sea-salt (nss)-SO42- at the East Antarctica ranges from 2.2 to 3.3‰, and the Δ17O value of nss-SO42- for coastal site was lower than those for inland site. Thus, this result suggest that oxidizing chemistry for biogenic sulfur is different among coastal and inland sites, although small sulfur isotopic variations are observed and source of sulfur is biogenic and homogeneous. For the isotopic compositions of NO3-, considerably increasing values of δ15N of NO3- are observed from coastal to inland sites. The δ18O and Δ17O of NO3- values, on the other hand, decreases with increasing of δ15N values, indicating the secondary formation of NO3-. Thus, spatial variations of isotopic compositions of NO3- reflect the post-depositional processes on the East Antarctic snow.