The Spatial Variations Of Trace Elements In Surface Snow Along The Transect From Zhongshan Station To Dome A,Antarctica

Lead,arsenic,and copper are some of the most concerned trace elements in terms of human health and environmental effects due to their bioavailability and toxicity.Trace elements exist naturally in the earth's environment in low concentrations,however,the global atmospheric cycle of trace elements has significantly changed by human disturbance in many regions of the Earth 's surface.These alterations are well preserved in snow and ice cores in Antarctica that can be utilized to reflect past climatic and environmental changes and present pollution situations.Currently,the spatial distribution patterns of trace elements,being apt to be influenced by different source processes of atmospheric aerosol,are not yet fully understood.In this study,58 continuous surface snow samples were collected along a 1228km transect from Zhongshan Station to Dome A during the 26th CHIN ARE in 2009/2010 austral summer.Samples were analyzed for trace elements,including Pb,As,and Cu by Inductively Coupled Plasma Sector Field Mass Spectrometer(ICP-SFMS).Three main findings are listed below.1.Source identification shows Pb,As,and Cu are all primarily derived from anthropogenic pollutants(all larger than 80%),volcanic emissions account for the major parts of natural sources(5-15%).2.Pb,As,and Cu show distinguishing spatial distribution along this route,and As shows much more moderate variation than Pb and Cu.In view of concentration,Pb and Cu show extremely high concentrations due to local human activities(0.98 pg·g-1 and 17.9 pg·g-1),and As kept a low concentration level in the coastal area(0.37pg·g-1).In the intermediate area,the concentration and enrichment factors for all three elements show the highest variability due to the mixture of air masses from coast and inland.In the inland plateau,the higher concentrations of As and Pb(2.16 pg·g-1 and 0.46 pg·g-l)are induced by more effective deposition mechanism,the existence of polar stratospheric precipitation and the spatial distribution of pollutants deposited to East Antarctica.In view of flux,Pb and Cu fluxes show similar characteristics with those of concentrations.However,As flux shows distinguished different trends with that of concentration.The different pattern between concentrations and fluxes can reflect wet and dry deposition,the results shows that the dry deposition is significant for Pb,less for As,minimum for Cu(41.2%,6.0%and 0%,respectively).All of them shows more significant for dry deposition in the inland area than in other areas.The results suggest that substances source,transport pathway and deposition pattern are more vital factors to substance fallout on entire Antarctica than distance inland or altitude.3.Over entire Antarctica,As concentrations show a significant gradual decreasing trend along the direction from Dronning Maud Land,Princess Elizabeth land,Victoria Land to West Antarctica,which reflects the transport pathway of particles derived from South America to Antarctica.No apparent spatial distribution pattern is founded for Pb due to multi-source and long-range transport Pb mixing well in Antarctic atmosphere.Cu concentrations in West Antarctica are apparently higher than that of East Antarctica,and it may be because of that the fast lower-level advection is prior to Cu.Pb and Cu show extremely high concentration in certain sites influenced by local human activities as the same characteristic with that of our traverse.These spatial patterns may reflect the source and transport pathway of different anthropogenic particle-bound metals.