Source Analysis And Pollution Loss Assessment Of Heavy Metals In Farmland Soil Based On UNMIX Model

Heavy metals,as pollutants that have been seriously harmful to the soil environment,not only destroy the natural ecology but also threaten human health,therefore,to find out the source of heavy metals and understand the current situation of pollution has become the first measure to protect against heavy metal pollution.In this paper,which is a town as a research area,in the autumn of 2015,53 sampling points were laid in the whole town,soil samples were collected,the concentration of 8 metal elements was measured,the distribution characteristics of metals in the region were analyzed,and the possible sources of heavy metals in the soil of the study area were analytic by factor analysis method and UNMIX model method.By using the natural neighborhood method of ArcGIS Point generation,the concentration rendering diagram of several heavy metals in the area is made,and the distribution law and causes of key heavy metals are traced and discussed in detail,and the results of source analysis are further supported.Finally,the pollution loss model is constructed,the local soil environmental quality is evaluated,and the economic loss of heavy metal pollution in local farmland is estimated according to the evaluation results.The following main conclusions are drawn: of the 53 soil samples in :(1) The mean values of Cd,Pb,Cu,Zn and Ni were higher than the soil background value of Jiangsu province,and the exceeding rate of Cd element was the highest.(2) Three main factors were analyzed by factor analysis method,of which factor 1 represented ceramic plant,waste accumulation,fertilizer application and pesticide use pollution source,factor 1 contributed the most to pollution sources,accounting for 32.7%,Factor 2 represented traffic and automobile exhaust and other sources of human activities,the contribution rate to the source was 25.6%,and factor 3 represented the soil parent source.With the lowest contribution rate to the source,at 16.3%.(3) Using UNMIX method to analyze four sources: source 1 on behalf of ceramic industry,three wastes emissions,sewage irrigation and other human activities caused by pollution sources,the source contribution rate of 24.963%,source 2 on behalf of fertilization,pesticide use and other agricultural activities,source contribution rate of 25.017%,source 3 represents the transport activities of human pollution sources,Source contribution is 25.004%;source 4 is 4 considered to be the source of pollution caused by soil parent matter,and the contribution rate is 25.016%.Factor analysis and UNMIX two analytical methods show that the results of factor load analysis and the results of concentration analysis are basically consistent,and the two methods have been applied to the study of soil heavy metal source analysis,and good results have been obtained.(4) Using pollution loss model,it is shown that the comprehensive pollution loss rate of 53 sampling points is between 6.09%~24.17%,the overall pollution level is ? grade,and the loss of heavy metal pollution in the study area is estimated at 9.5509 million yuan per year.The results obtained by using Nemero Composite Index method are similar to the comprehensive pollution loss rate method,which shows that the pollution loss model can better reflect the overall heavy metal pollution situation and the loss of soil quality in the study area,and provides a certain basis for the subsequent quality improvement of the local polluted land.