Safe Utilization Evaluation And Regulation Of Agricultural Land Soil Contaminated By Heavy Mental Elements In A Chinese County

Land resource is a unique treasure as nature’s present for humanity,and it nourishes all beings.It is also the cornerstone of all human civilizations and the rarity of a nation.Land resource is critical for the development but very limited in China.Soil environmental pollution problem is increasingly severe in China in recent years.Regional agricultural land soil security is the first barrier for the safety of agricultural products,since its quality directly relates to the food security.This thesis attempted to characterize the spatial variation of As,Cd,Cu,Hg,Pb and Zn in topsoil by robust basic descriptive statistics analysis,data processing,spatial variation and spatial interpolation analysis.The results showed that,these six heavy metal elements were all clustered spatial distributions with significant skewed characteristics.Their distributions were influenced by natural factors and human factors simultaneously.Then IDW space interpolation prediction results were the best when using the NST data of six heavy metal elements.They transferred points features to areal.This analysis methodology can provide a quantitative and reasonable support for the relevant studies in the future.This thesis indicated a spatial statistical relationship between each of the six heavy metal elements and potential determinant variables by GeogDetector Model(GDM).Factor detector results showed that,the top five potential risk factors of these six heavy metal elements included both natural factors and social-economic factors.Interaction detector results showed that,interactions of potential risk factors all enhance nonlinearly.The specific categories of each potential risk factor could be identified by risk detector for each heavy metal element.GDM results can help identify and monitor the heavy metal contaminated areas.In this thesis,the evaluation standards of soil heavy mental elements exceed were integrated based on those standards of the existing soil environmental quality assessment and food safety evaluation in different pH of soil and different secondary land use types for “classification management”.The status evaluation of agricultural land soil heavy mental elements exceed standards was based on "single factor index method,inside,the comprehensive pollution index method and potential ecological risk index method" for “risk control principle”.The results included 5 grades.The buffer filtering function evaluation of agricultural land soil heavy mental was based on “pH,CEC,TOC and Clay,minimum standard capacity coefficient(MSECI)” for “prevention first principle”.The results included 3 grades.The safe utilization evaluation of agricultural land soil heavy mental elements exceed standards was integrated by the status evaluation and buffer filtering function evaluation effectively.The results included 4 levels and 15 classes.In this thesis,three regulation of empirical studies were carried out on the permanent prime farmland adjustment and cultivated land safe utilization monitoring management in county scale and agricultural cropping system adjustment in town scale.Different use Planning and recommendations varied from different partitions,classifications and grades.This method is benefit for the improvement of the ideas of agricultural land use and management,promoting rational utilization of land resource,achieving the highest production,social-economic benefits and ecological benefits of land resource and promoting land resources "trinity" controls.