Agricultural Land Pollution Sources Apportionment And Comprehensive Quality Evaluation

Soil is one of the natural environmental factors for human survival.Its fertility and soil environmental quality are the focus of many researchers,but few studies combine two systems to assess soil quality.In this paper,based on the investigation of 11 physicochemical indexes of organic carbon,total nitrogen,total phosphorus,total potassium,available phosphorus,available potassium and pH in soil and 8 heavy metal contents of Cd,Hg,As,Pb and Cr in soil,the research on the apportion of soil heavy metal sources was carried out,and the comprehensive quality evaluation of soil was carried out based on the classification of soil risk management and the evaluation of soil fertility.The main conclusions are as follows:(1)The results of soil heavy metal source apportion showed that although the soil type and land use pattern of the study area are different,the RPCA-APCS-RGWR model can correct the loss of information and make the source identification and source apportionment more consistent.This model divides the heavy metal sources in the study area into five types: agricultural sources,industrial sources,traffic sources,comprehensive sources and natural sources.This model can reduce the occurrence of negative values of source contributions and bring a higher degree of fit to the apportionment of the main source.(2)The results of soil physicochemical properties analysis showed that the soil formation time,soil development degree and soil parent material source significantly affected the total phosphorus content in the soil.Compared with total phosphorus,soil parent material has a greater impact on selenium.Among the effects of total nitrogen and SOC,soil aeration conditions and land use type play a decisive role.In this study,PF often takes a rotation,and the dry process increases the input of SOC.The poor soil aeration conditions of PF are the main reason for the increase of nitrogen accumulation.(3)Soil comprehensive Quality Evaluation introduced robust principal component analysis to evaluate soil fertility of different soil types and land use types.The comprehensive scores of soil fertility were CS > PS > MS > RS > YBE;IL > PF > DL > OR > TG.Use the soil pollution risk screening value and control value to classify the types of soil pollution risk control in the study area.The first type is the priority protection category,the content of heavy metals is lower than the soil pollution risk screening value.In the study,77.01% of Cd samples,98.85% of Cr and Ni samples,97.70% of Cu samples and All samples of the other five heavy metals belong to this type.The second type is safe use category,the content of heavy metals is between the soil pollution risk screening value and the control value,Cd has 19.54% samples,Cu has 2.30% samples,Cr and Ni have 1.15% samples belong to this type.The third type is strictly controlled category,3.45% of Cd samples belong to this type.Based on the calculation of comprehensive scores of soil fertility and types of soil pollution risk control,the sample points were modified and the corresponding soil comprehensive quality scores were calculated.The soil comprehensive quality scores were PS > MS > CS > RS > YBE;PF > OR > IL > DL > TG.