Brief communication: Spatial and temporal variations in surface snow chemistry along a traverse from coastal East Antarctica to the ice sheet summit (Dome A)

To better understand snow chemistry in different environments across the Antarctic ice sheet, we investigated snow ions on a traverse from the coast to Dome A. Results show that the non-sea-salt (nss) fractions of KC, Mg2C, and Ca2C are mainly from terrestrial particle mass and nssCl Is associated with HCl. Spatially, the non-sea-salt fractions of ions to the totals are higher in the interior areas than on the coast, and seasonally, the proportions are higher in summer than in winter. Negative nssSO2 4 on the coast indicates sea salts from the sea ice, and marine biogenic emissions dominate snow SO2 4 in interior areas throughout the year ions (e.g., NaC and Cl), in general, are the most abundant species and typically exhibit a clear spatial trend, with concentrations falling off sharply with distance from the coast. Temporally, with varied sources and lifetimes, ions in snow often exhibit different seasonal variations; e.g., seasalt-related ions show high concentrations in winter, while elevated concentrations of SO2 4 and NO 3 are frequently observed in summer (Neubauer and Heumann, 1988; Gragnani et al., 1998; Traversi et al., 2004; Shi et al., 2015). On annual to decadal timescales, ion concentrations in snow and ice tend to be associated with changes in transport from year to year (Severi et al., 2009; Weller et al., 2011), and thus largescale atmospheric and oceanic circulation in the Southern Hemisphere could potentially influence variations in snow and ice chemistry (Russell and McGregor, 2010; Weller et al., 2011; Mayewski et al., 2017). Although investigations of snow chemistry have been carried out along several overland traverses, the investigation of snow chemistry under different environmental conditions and over time is needed, given that the Antarctic ice sheet itself and precipitation and deposition patterns and trends are changing. The Chinese inland Antarctic traverse from the coastal Zhongshan Station to the ice sheet summit (Dome A) covers a range of environments (1250 km); e.g., a high snow accumulation rate is present on the coast and in some interior areas and a low accumulation rate is observed on the Dome A plateau. Several investigations have been carried out to determine the concentrations of a few ionic species and trace elements on the traverse (e.g., Li et al., 2016; Du et al., 2019), but only limited snow chemistry data were previously available. Therefore, we used surface snow and snow pit samples collected during five Chinese inland Antarctic scientific expedition campaigns to determine the spatial and temporal variations and their controlling factors in a comprehensive set of ions (NaC, NHC 4 , KC, Mg2C, Ca2C, Cl, NO3 , and SO2 4 ).