Statistical Analysis For Geochemical Baseline Of Soil Heavy Metals In Qingdao

With economy increasing,the environment quality of Qingdao receives more and more attention.The soil quality is the important standard which can measure local environment.The contamination degree can reflect local environment quality to some extent.The heavy metal pollution is an important source of soil pollution,and the geochemical baseline as the reference value needs to be considered for the heavy metal pollution assessment.So how to obtain a reasonable geochemical baseline of Qingdao area already becomes the important question which currently needs to solve.In this article,the reasonable methods for determining the geochemical baseline are studied from some perspectives,and two different methods are obtained for the geochemical baseline of Qingdao area,then the best one as the reference value is carried on the soil heavy metal pollution assessment through the Geoaccumulation Index.Firstly,Statistical methods to determine geochemical baseline of soil heavy metals in Qingdao are studied.We select the Li element as the independent variable of linear regression through the correlation coefficient between inert elements and pollution elements.In order to make the data of pollution elements follow a normal distribution,we make the Box-Cox transformation to them,and give two kinds of statistical methods to determine geochemical baseline of soil heavy metals in Qingdao:the normalization method and the robust regression method,sequently compair the two methods based on residual analysis.The result indicates that the fitting effect of the normalization method is better than the one of the robust regression.method.Secondly,the Geoaccumulation Index of 7 heavy metal elements are calculated with taking the geochemical baseline which comes from the normalization method as the reference value,and then put up the pollution assessment.The result indicates that the level was sequencely obtained as Ni<Cd<Pb<Cr<Cu<Zn<Hg,and heavy or extremely heavy pollution were mainly in the area which suffer from a lot of industrial product,transportation and human activities.