The Study On Source Tracking Of Se Anomaly And Ecological Appraisal In Plain Terrain Of Hebei

As a kind of mecroelement,Selenium is necessary for human life and activities. 1/250000 geological survey in Hebei Plain shows that the content of Se in soil is low but it exists Se anomalous zone in some research areas. This Se anomalous zone in Hebei Plain is our research object. We carry out tracing of anomalous sources of Se and ecological effects evaluating and the purpose is to provide geochemical evidence for local agricultural structure adjustment.The program of "Hebei province agriculture geological investigation" carried on sampling test to farmland soil in plain area of Hebei province. According to the analytical result of soil samples, the author divides plain area of Hebei province into two big districts and eleven soil-forming sedimentary evironment subranges by analyzing geological background, soil, landform, hydrology and other factors synthetically. Comparative analyses of contents of Se in surface and deep soil of each subrange show that the content of Se in Hebei Plain is low and uneven distribution, and exists Se enrichment zone in Tangshan,Banding, Shijiazhuang -Handan.The research delimits the Se anomalous scope and the anomalous lower limit of this local through contrastive analyses between deep and shallow layer soil and data processing utilizing X±nS(n=1.5～3). According to the content difference between deep and shallow layer soil, Se geochemical background, transect analysis of anomalous zone and cluster analysis, we carried out the analysis of anomalous cause and the result shows that the anomalous sources in shallow layer soil are relative to man-made factor mainly and estimates the propotion of man-made fator and natural fator is 3:1.Based on the content of Se in rock samples, soil samples, irragating water, atmosphetic dust and fertilizers, the research estimate the anomalous sources and point out the anomalous sources in deep layer soil are not relative to man-made factor but controlled by regional geological background; the content of Se in shallow layer soil is affected by geological background and man-made fator. In addition, the author points out the main man-made factors of Se utilizing flux research in Hebei Plain.Response relation equation is established through studying the corelation between Se in wheat seed and corn seed and in root soil. Based on the response relation equation and multiple target geochemical data, we estimate the content of Se in wheat seed and corn seed and evaluate the safety of crops systematically in research areas. According to grading standards of Se in soil, the research grade the soil in Hebei Plain and determine the area and proportion of each grade, and provide scientific evidence for agricultural structure adjustment of Hebei province.