Distributions and Sources of Phosphorus in Surface Soils of Chengdu Basin

This study investigates distribution of concentration of phosphorus in surface soils in Chengdu basin,Sichuan Province.The study area is divided into three parts: Longmenshan mountain area,hill area and plain area.Abnormal enrichment of phosphorus in mainly found to be distributed in the plain area by the factor score isopleth maps,characterized by high density of population and long history of industrial and agricultural activities.16 elements with close relation in surface soils are examined by factor analysis.The results is: ①the natural source of phosphor in study area is stratums containing phosphorous(the deposits of phosphorus),such as Sinian,Cambrian and Devonian in Longmenshan mountain,all the paddy soils in plain area are influenced by erosion process by three big rivers-Tuojiang River,Minjiang River and Pujiang River;②another source is the activities of industry and agriculture,which overlaps on natural soils through anthropogenic activities.