Soil Heavy Metal Pollution Traceability And Risk Assessment Based On Atmospheric Diffusion Simulation

Soil heavy metal pollution is becoming increasingly serious,and accurate traceability of pollution is extremely important for effective prevention and control of soil pollution.Traditional source analysis methods mostly use receptor models,which are prone to inaccurate results in the study of heavy metal pollution in soils,making it difficult to eradicate the pollution.In order to accurately trace the sources of heavy metal pollution in soil and their contributions,and to predict the trends of changes in soil heavy metal content due to various sources of pollution,as well as the resulting trends of increased ecological and human health risks,this study develops a method for tracing the sources and assessing the risks of heavy metal pollution in soil based on atmospheric dispersion and deposition dynamics simulations.The method mainly includes four parts:potential pollution source analysis and source strength solution,atmospheric dispersion and deposition simulation,quantitative heavy metal traceability model,and risk prediction and assessment.The types and distribution of potential pollution sources are clarified,the main forms of pollutant transport are analysed,the main sources and the main pathways of heavy metal migration and diffusion into the soil receptors are identified,and the source strength of each source is calculated using a mathematical model of source release.A three-dimensional shared grid is established in the study area,and the CALMET module is used to develop the actual meteorological field over the study area.The CALPUFF model is used to superimpose the wind field data with the pollutant source information to simulate the kinetic processes of the diffusion of pollutants released from multiple sources in the atmosphere and their deposition in the soil.The incremental concentration of heavy metals in the soil and the contribution of each source to the heavy metal elements are calculated based on the pollutant deposition and the content of each heavy metal,and the above results are verified using the measured incremental data and the PMF model.The potential ecological risk index was used to measure the contribution of each pollutant source to ecological risk,and the human health risk assessment model was used to assess the extent of the impact of increased heavy metal content in soil on the carcinogenic and non-carcinogenic risks to humans.In this study,the pollution sources of six soil heavy metals(Zn,Pb,Ni,As,Cd and Cr)were analysed and the pollution status was assessed in a region in southwest Suzhou,Jiangsu Province,China.The study identifies the spatial distribution of each heavy metal and the sources and contributions of pollution;it reveals the distribution pattern of pollutants under the influence of wind direction and seasonal-related climatic factors(temperature,humidity,precipitation and wind speed,etc.).The risks are relatively high for farmland and road sources throughout the study area;the ecological risks are higher for Cd and Pb;the non-carcinogenic risks for humans are higher for Pb,As and Cr,and the carcinogenic risks for humans are higher for Cr.By simulating the kinetic process of pollutant release from the source,diffusion and migration in the atmosphere,and deposition to the receptor soil,and quantifying the contribution of each source based on the content of heavy metals in the pollutant,this study improves the accuracy of the source analysis of soil heavy metal pollution in an active traceability way,and achieves an objective and effective assessment of the existing land pollution situation,and at the same time can predict the future trend of soil pollution with a clear understanding of the pollution situation and source strength.It is also possible to predict future soil pollution trends with a clear understanding of the pollution status and source intensity,and to lay a theoretical foundation for current land use and planning.Based on the changes in soil heavy metal content and cumulative growth trends,the risk assessment method is used to predict the trends in ecological risks and human health risks resulting from these changes,providing a comprehensive and systematic evaluation of soil heavy metal pollution in the study area,providing a scientific basis for the comprehensive evaluation of soil heavy metal pollution and a theoretical basis for taking effective measures to prevent and control soil pollution.