Security Regional Division And Control Strategy Of Heavy Metal Elements In Farmland Soil In North Of The North China Plain

In recent years,the pollution of heavy metals in agricultural soil in China had become more and more serious,which had seriously jeopardized soil safety and human health.Therefore,the study on the pollution status of heavy metals in regional farmland soil were of great significance to promoted the risk early warning,restoration control and safe utilization of agricultural land.In order to fully reveal the distribution of heavy metals in agricultural land of different soil depths,comprehensively explore the “partitioning” scheme of agricultural soil that can be replicated and promoted,and the strategies of efficient,safe and sustainable use,this paper took the “sustainability concept” of land use as the starting point and collected the soil samples of the agricultural land surface(0~25cm)and subsurface layer(25~50cm)in the plain of Beijing,the contents of Cd,Cr,Pb,As and Hg were determined.Based on the preliminary analysis of the distribution characteristics of soil heavy metals in different soil depths,the geostatistical analysis of ArcGIS was used to evaluated the risk degree of heavy metals.Finally,the safety utilization evaluation method of heavy metal was built based on geo-accumulation index,improved geoaccumulation comprehensive index and potential ecological risk index.Combined the spatial correspondence between different risk factors and heavy metals to carried out analysis of heavy metal pollution sources,and proposed land division management and differential remediation measures for the analysis results.The main findings were as follows:(1)The pollution risk and ecological hazard of heavy metals in soil in the study area were mainly mild.And the areas with slight ecological hazards in the surface and subsurface soil accounted for 71.31% and 94.39%,respectively.The ecological hazards around the urban area were highest,and gradually decreased to the surrounding areas.Among them,the number of contaminated samples of Cr and As exceeded 50% of the total,which were the dominant factors of risk in the area.(2)The pollution risk and ecological hazard of heavy metals in soil in the study area were mainly mild.And the areas with slight ecological hazards accounted for 71.31%(0~25 cm)and 94.39%(25~50 cm),respectively.The ecological hazards around the urban area were highest,and gradually decreased to the surrounding areas.Among them,the number of contaminated samples of Cr and As exceeded 50% of the total,which were the dominant factors of risk in the area.(3)According to the scheme for the regional division,the study area was divided into four types of zones,which were: safe utilization,low-risk,medium-risk,high-risk.The results showed that the low-risk states were dominated in the study area,and the artificial sources were the main cause of heavy metals accumulation in the region.According to the different security zones,the fine classification management was proposed.Among them,the safety zone should carried out the protection and upgrading of land quality to promoted a virtuous cycle of its ecosystem;the risk zones must strictly controlled industrial sources,agricultural sources,and sources of domestic pollution to shorten the route of transmission of pollution sources.;The polluted area should carried out the control and restoration of the land so as to explored a reasonable and healthy prevention and control model.Figure [17] table [13] reference [107]...