Antarctic Science page 1 of 7 (2010) & Antarctic Science Ltd 2010 doi:10.1017/S0954102010000155 Glaciochemistry of surface snow from the Ingrid Christensen Coast, East Antarctica, and its environmental implications M. THAMBAN 1 *, C.M. LALURAJ 1 , K. MAHALINGANATHAN 1 , B.L. REDKAR 1 , S.S. NAIK 1 and P.K. SHRIVASTAVA 2 1 National Centre for Antarctic and Ocean Research, Headland Sada, Vasco-da-Gama, Goa 403 004, India 2 Geological Survey of India (Antarctica Division), NH-5P, N.I.T., Faridabad 121001, India *meloth@ncaor.org Abstract: Spatial variations in the ion composition were studied in 55 surface snow samples collected along three transects in the Ingrid Christensen Coast of East Antarctica. The sea-salt ion constituents revealed a drastic reduction from the ice edge to inland sites. The computed sea-salt sodium and non-sea- salt calcium concentrations suggest that while sea spray primarily contributes to the Na 1 , the crustal contribution dominates the Ca 21 in snow samples. The Cl - /ssNa 1 ratios of the snow samples from the Larsemann transect varied between 4.7 and 1.05, indicating that additional Cl - sources like soil dust are important in the inland sites. The enrichment factors (Ef) confirm a dominant crustal source for Ca 21 in all transects. The Ef(K 1 ) values indicate a dominant sea spray source for K 1 in the coastal stations of the Larsemann and Publications transects. The Ef(Mg 21 ) values indicate the absence of any significant Mg 21 enrichment compared to seawater values. Secondary sulphur species (nssSO 4 2- and MSA) within the snow samples suggest that both vary independently of each other, possibly influenced by the local biological activities. The nssSO 4 2- data revealed that several summer snow deposits in the study region are significantly fractionated, apparently related to the sea ice existence during summer. Received 30 April 2009, accepted 6 February 2010 Key words: ion composition, Larsemann Hills, non-sea-salt sulphate, sea-salt aerosol Introduction Antarctic snow and ice represent one of the most pristine archives for environmental studies. Studies on the Antarctic snow and ice chemistry therefore, not only provide information on the aerosol sources, but also the tropospheric transformation processes and prevailing long-range transport mechanisms and patterns. However, various scavenging processes as well as post-depositional effects influencing the atmospheric chemistry have been recorded in the snow (Whitlow et al . 1992, Legrand & Mayewski 1997, Ro ¨thlisberger et al . 2000, Traversi et al. 2004, Ka ¨rka ¨s et al . 2005, among others). It is also well known that Antarctica exhibits large-scale spatial and seasonal variations in snow accumulation and chemical properties (Bertler et al. 2005). Continental-wide studies of snow deposits are thus imperative for an accurate understanding of the Antarctic variability and its influence on the climate records (Kreutz & Mayewski 1999, Udisti et al. 2004, Bertler et al. 2005). Among the various aerosol species found in coastal Antarctica, the primary aerosols are comprised essentially of sea spray and crustal components, whereas the secondary aerosols are mainly of biogenic origin since anthropogenic activities are negligible in Antarctica (e.g. Legrand & Mayewski 1997, Udisti et al. 1999). Sea spray is the main contributor to the ionic budget of coastal Antarctic aerosols and has immense importance due to its potential role as reaction sites for reactive gases (Wagenbach et al. 1998). Although sea spray is mainly produced by bubble bursting, it could also be influenced by the wind and wind direction, as well as seasonal variations in the sea ice cover (Keene et al. 1986, Legrand & Delmas 1988, Wagenbach et al. 1998, Rankin et al. 2002). The ionic composition of sea spray in Antarctic snow shows large spatial and temporal variations and is influenced by various factors like accumulation rates, elevation and relative distance from sea (Hall & Wolff 1998, Becagli et al. 2004, Benassai et al. 2005, Bertler et al. 2005). However, our understanding of the seasonal extent and spatial variations in the fractionation of sea spray and its interaction with secondary ionic sources is very limited. It is in this context that the present study was undertaken in order to study the major ion composition of surface snow along three transects along the Ingrid Christensen Coast of East Antarctica during the late summer of 2006–07 (Fig. 1). The main objective of the study was to evaluate the spatial variability of major ion species in snow and its implications for the atmospheric and oceanic biogeochemical processes in coastal Antarctica. Materials and methods The study region is comprised of three coastal transects (Larsemann, Publications and Amery) along the Ingrid Christensen Coast of East Antarctica (Fig. 1). The study 1