Temporal variations in marine chemical concentrations in coastal areas of eastern Antarctica and associated climatic causes

摘要

Snow pit (and a firn core) samples obtained from coastal areas in the eastern Lambert basin of eastern Antarctica enabled us to investigate the temporal variations in soluble marine ion concentrations and the possible mechanisms influencing their variations. The concentrations of seasonal sea salt ions (Na~+, Cl~-and Mg~(2+)) at the coastal site (LH406) were maximal in the spring and minimal in the summer; broad maximal values also occurred in the winter and minimal values occurred in the summer in the interior site (ZG050). The sea ice extent (SIE) in the Indian Ocean sector of eastern Antarctica followed similar temporal distribution patterns. Two sulfur compounds (SO_4~(2-) and MSA) experienced seasonal variations similar to those observed for sea salt ions at the LH406 site. However, distinct variations were reported at the ZG050 site. The variations in nssSO_4~(2-) levels in the ZG050 snow pit that occurred over a 14-year period were positively correlated with variations in SIE. However, this relationship was different from that at the western Lambert basin. The change in direction of the supplementary prevailing wind during 1994-1995 produced a significant change in the concentrations of marine ions. A change in the source region may be the primary cause of this difference.