Chemical composition of snow-water and scavenging ratios over costal Antarctica

Snow samples and aerosol samples were collected at coastal Antarctica near Larsemann Hills and Maitri, during the 29th Indian Antarctic Expedition carried out during Dec., 2009 to March 2010. The main objective of this study was to characterize the chemical composition of fresh and surface snow at coastal Antarctica and to determine the scavenging ratios using composition of snow and aerosol samples. The pH of surface and fresh snow were 6.03 and 5.64 respectively. The surface snow samples were collected along a 127-km transect from the seaward edge of the ice shelf to the Antarctic plateau and analyzed for the presence of the major inorganic components SO4 2-, NO3 -, Cl-, NH4 +, Na+, K+, Ca2+ and Mg2+. It was observed that Na+ and Cl- were the most abundantly occurring ions at Antarctica. Considerable amount of SO4 2- was also found in the both fresh and surface snow which may be attributed to the long range transport from Northern Hemisphere as well as to the oxidation of DMS produced by marine phytoplankton. A higher percentage of the ions in fresh snow may be because of trapping of the particulate matter in it. The sea-salt components i.e., Na+, Cl- and Mg2+ decreased with increasing distance from the coast. The acidic components were neutralized mainly by NH4 + and Ca2 +. The scavenging ratio was maximum for Na+ and minimum for NO3 -, indicating that the scavenging efficiency was higher for coarse size particles and lower for fine size particles. In addition, we have attempted to find out the possible sources of the observed chemical species in snow-water