Journal of Atmospheric Chemistry 17: 95-122, 1993. 95 © 1993 Kluwer Academic Publishers. Printed in the Netherlands. Nitrogen and Sulfur Species in Antarctic Aerosols at Mawson, Palmer Station, and Marsh (King George Island) D. L. SAVOIE, J. M. PROSPERO, R. J. LARSEN 1, HUANG, F., M. A. IZAGUIRRE, HUANG, T., T. H. SNOWDON, L. CUSTALS, and C. G. SANDERSON 1 Division of Marine and Atmospheric Chemistry, Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, FL 33149-1098, U.S.A. 1Environmental Measurements Laboratory, Department of Energy, New York, N Y 10014, U.S.A. (Received: 21 February 1992; in final form: 21 January 1993) Abstract. High volume bulk aerosol samples were collected continuously at three Antarctic sites: Mawson (67.60 ° S, 62.50 ° E) from 20 February 1987 to 6 January 1992; Palmer Station (64.77 ° S, 64.06 ° W) from 3 April 1990 to 15 June 1991; and Marsh (62.18 ° S, 58.30 ° W) from 28 March 1990, to 1 May 1991. All samples were analyzed for Na +, SO 2-, NO3, methanesulfonate (MSA), NH~, 21°pb, and 7Be. At Mawson for which we have a multiple year data set, the annual mean concentration of each species sometimes vary significantly from one year to the next: Na +, 68-151 ng m-3; NO?, 25-30 ng m 3; nss SO]-, 81-97 ng m-3; MSA, 19-28 ng m 3; NH], 16-21 ng m-3; 21°pb, 0.75-0:86 fCi m -3. Results from multiple variable regression of non-sea-salt (nss) SO42- with MSA and NO3 as the inde- pendent variables indicates that, at Mawson, the nss SO]/MSA ratio resulting from the oxidation of dimethylsulfide (DMS) is 2.80 ___ 0.13, about 13% lower than our earlier estimate (3.22) that was based on 2.5 years of data. A similar analysis indicates that the ratio at Palmer is about 40% lower, 1.71 _+0.10, and more comparable to previous results over the southern oceans. These results when combined with previously published data suggest that the differences in the ratio may reflect a more rapid loss of MSA relative to nss SO4 z- during transport over Antarctica from the oceanic source region. The mean 21°pb concentrations at Palmer and Marsh and the mean NO3 concentration at Palmer are about a factor of two lower than those at Mawson. The 21°Pb distributions are consistent with a 21°pb minimum in the marine boundary layer in the region of 40°-60 ° S. These features and the similar seasonalities of NO 3 and 21°pb at Mawson support the conclusion that the primary source regions for NO 3 are continental. In contrast, the mean concentrations of MSA, nss SO] , and NH2 at Palmer are all higher than those at Mawson: MSA by a factor of 2; nss SO42- by 10%; and NH~ by more than 50%. However, the factor differences exhibit substantial seasonal variability; the largest differ- ences generally occur during the austral summer when the concentrations of most of the species are highest. NH~/(nss SO 2- + MSA) equivalent ratios indicate that NH 3 neutralizes about 60% of the sulfur acids during December at both Mawson and Palmer, but only about 30% at Mawson during February and March. Key words. Antarctica, Palmer, Marsh, Mawson, aerosol particles, biogeochemical cycles, sulfate, nitrate, methanesulfonate, lead-210, beryllium-7, sea-salt, ammonium. 1. Introduction Understanding the atmospheric chemistry of the Antarctic is crucial for several reasons. Because this region is far removed from major pollution sources, the