Spatial variations of Pb,As,and Cu in surface snow along the transect from the Zhongshan Station to Dome A,East Antarctica

The spatial distributions of lead, arsenic, and copper （Pb, As, and Cu, respectively） in surface snow along the transect from the Zhongshan Station to Dome A, East Antarctica, are presented. The mean concentrations of Pb, As, and Cu are 1.04±1.56 pg/g, 0.39±0.08 pg/g, and 11.2±14.4 pg/g, respectively. It is estimated that anthropogenic contributions are dominant for Pb, As, and Cu. Spatially, Pb concentrations show an exponentially decreasing trend from the coast inland, while a moderate decreasing trend is observed for Cu concentrations in the coastal area （below 2,000 m above sea level （a.s.1.））. In the intermediate area （2,000-3,000 m a.s.1.）, the concentrations and enrichment factors of all these elements show high variability due to the complicated characteristics of climate and environment. On the inland plateau （above 3,000 m a.s.1.）, the high concentrations of As and Pb are induced by high deposition efficiency, the existence of polar stratospheric precipitation, and the different fraction deposition to East Antarctica. The extremely high concentrations with maximum values of 9.59 pg/g and 69.9 pg/g for Pb and Cu, respectively, are suggested to result mainly from local human activities at the station. Our results suggest that source, transport pathway, and deposition pattern, rather than distance from the coast or altitude, lead to the spatial distributions of Pb, As, and Cu; and it is further confirmed by spatial variations of the three metals deposited over the whole continent of Antarctica.

青藏高原冰芯记录揭示早-中全新世发生多次融水事件

Understanding the impact of meltwater discharge during the final stage of the Laurentide Ice Sheet(LIS)has important implications for predicting sea level rise and climate change.Here we present a highresolution ice-core isotopic record from the central Tibetan Plateau(TP),where the climate is sensitive to the meltwater forcing,and explore possible signals of the climate response to potential LIS meltwater discharges in the early to mid-Holocene.The record shows four abrupt large fluctuations during the 7–9 ka BP(kiloannum before present),reflecting large shifts of the mid-latitude westerlies and the Indian summer monsoon(ISM)over this period,and they corresponded to possible LIS freshwater events documented in other paleoclimate records.Our study suggests that multiple rapid meltwater discharge events might have occurred during the final stage of LIS.The finding implies the possibility of rapid sea level rise and unstable climate in the transition zone between the mid-latitude westerlies and the ISM due to fast polar ice retreat under the anthropogenic global warming.