metal element enrichment characteristics of sediments in chaohu lake since the 1860s and its implication to human activity

Sample core CH1 with a length of 141 cm was drilled in the deepest part of Chaohu Lake by the Gravity Impact Core Sampler,and divided into 113 sediment samples in which a set interval is applied to pick about every 1 cm or 2 cm.We carried out the test and analysis of the core CH1 on the specific activity of 210Pb and 137Cs,magnetic parameters,granularities and 14 indicators of metal elements such as Cu,Zn,Al,Fe and so on.Based on the above study,the deposition rate is extrapolated with the specific activity of 210Pb and the chronological surveying rod of the deposit is built,then the relation between the enrichment of metal elements and the characters of granularity magnetism is analyzed.It is found that there are remarkable correlations between the contents of metal elements such as Cu,Zn,Al,Fe and so on,and the value of clay contents,magnetic susceptibility,SIRM.According to grain-size effect correction of metal element contents with the mean value of metal element contents from the 10 samples at the bottom of core CH1 instead of soil background values of metal element around Chaohu Lake area,it is found that the contents of Cu and Zn in deposit have increased with unnatural levels since the 1860s AD.Based on the extrapolative age of deposition rate,which was closely related with the industrial activity such as the high temperature combustion of fossil fuel,metal smelting and machine facture and so on,it is thought that the result is caused by human activity impacts.This situation,not only temporarily but also in metal pollution characters,coincides with the establishment of Anqing Inner Armory in 1861,the first Chinese arsenal in modern time,which mainly produced firearm,ammunition and steamship.It is indicated that the enrichment of metal elements such as Cu,Zn and so on,with unnatural levels is the sedimentary response to the origin of Chaohu Lake regional industry in modern time and the human industrial activity.