摘要
Within the limits of 13 000 km2 in Yantai of Shandong Province,totally 408 top soil samples were collected with the density of one sample/36 km2,and 10 indices such as HCH and DDT were determined.By studying the variation of the content,the authors have found that the soil has remaining HCH and DDT whose use has been prohibited for nearly 30 years,and some samples have relatively high content.According to environmental quality standard for soils evaluation,Ⅲ grade and Ⅲ-exceeding grade soils appear in the study area.In addition to α-HCH,β-HCH has the most high content in the four isomers of HCH,and DDT mainly existent in the forms of P,P′-DDE and P,P′-DDT.Furthermore,indicated by the changing rule of w(α-HCH)/w(γ-HCH),w(β-HCH)/w(γ-HCH)and[w(P,P′-DDE)+w(P,P′-DDD)]/w(P,P′-DDT),the authors have induced that HCH has been used for a long time within the study area,and locally there doesn’t exist new pollutant source input.In most areas,the use of DDT was stopped long time ago,and their compositions have undergone considerable change through physical and chemical actions,so the pollutant must have been formed in the past.In 4.41% of the study area,there may exist new pollutant source input in recent years,to which we must pay sufficient attention.