关键词: 北极, 沉积地球化学, 气候, 环境

Abstract: The paper deals with ass emble feature and distribution of chemical elements in the borehole AB-67 covered a time span of past 450 years from Elson lagoon in Barrow of Arctic Alaska. The correlation between the contents of clay and organic matter and the concentration of chemical elements are described. The analysing data show that the concentrations of major elements(SiO₂,Fe₂O₃),trace elements(Ni,Cu,Zn and Pb)and rare an drare-earth element s(v,Co,Ga,S e,Y,Zr,Li,N b et c.)are qu it e differen t betw een th e upper part(0—20cm in depth)and the lower part(20—60cm in depth)of the borehole AB-67.In the lower part(20—60cm)SiO₂,Fe₂O₃,and A l2O3,account decreases by 76.24%,Fe₂O3 and Al₂O₃ increase up t o 3.39%and 7.21%respectively,in dicat in gastrent hening of chemical weathering which resulted in leaching of SiO₂ and enrichment of Al₂O₃ and Fe₂O3.Concen trations of Cu,Pb,Zn and Ni below the depth of 20cm in the coreareless than 15mg/kg,15mg/kg,70mg/kg and 20mg/kg respectively,while abovet hedept hof 20cm in the corethey are roughly double increased. The variation tendency of trace elements are coincided to that of silt and clay as well as the organic matter with a coefficient of correlation of 0.80.An cluster an alysis of chemical elements shows that the rere and rare-earth elements(V,Co,Ga,Se,Y,Zr,Li,Nb etc.)and the trace elements(Cu,Zn,Pb,Ni,Cr)are in a group with close positive linear relationship with a coefficient R=0.95,which shows that the elements are absorbed by clay and colloid and can be carried in sus pended sediments and accumulated together in the lagoon.The trans portation and accumulation of chemical element group infer that the catchment basin in Barrow has been apparently affected by chemical weat hering and biogenic proces ses under relatively a warm climate since 1827. Based on the characters of sed imen tary geochemistry of the borehole AB-67,t he history of climatic and environmental changes in Barrow in the past 450 years can be reconst ructed as follows:(1)A stage with a relatively cold and dry climate and a low sea level occured prior to 1700;(2)It was becoming warm accompanied with a transgression f rom 1700AD to 1827;(3) From 1872 to 1994(eg.0—20cm in depth of the borehole AB-67),it was fluetuated warming accompanied by continuous transgression;in this period relatively cold appeared around 1935 and 1969.This figure coincides with the results obtained from the study of tree-ring in northern Fen noscandinavia and the study of icecore on the Tibet an Plateau.

Key words: Arctic Barrow, lagoon, sediments geochemistry, climate, environment