Spatial-temporal Modeling Of Heavy Metal Pollution In Soil And Its Environmental Risk Warning

Abstract:Understanding the spatial-temporal distribution characteristics of he avy metals in soil is the premise of contaminated soil remediation. The way to identify spatial distribution of heavy metals contamination characteristics in so il mostly rely on spatial interpolation methods which are determined by sampli ng analysis in the field. However, concentrations estimated by spatial interpola tion methods are generally with low accuracy and are not enough for accuratel y defining boundaries of heavy metals contaminated soil in an area, due to the limitations of sparse sampling conditions and insufficient budgets. Moreover, t he priority of remediating heavy metals contaminated soil in a certain area is a lso problematic which should be further based on the temporal variations of he avy metals, state investment, and technical feasibility.In this study, the field survey data and information related to heavy metal s contaminated soil were collected in XX city of southern china. Based on the spatial variability analysis of heavy metals concentration using geostatistical methods, co-kriging interpolation models were established to create continuou s surfaces of heavy metal concentrations of the entire city area. With the help of scenario prediction method, heavy metal concentrations of entire city area i n year2020were also predicted by using the continuous surfaces in spatial di mension as inputs. After this, the environmental security warning of heavy me tals contaminated soil was released in perspectives of soil environmental quali ty and human health risk. Results indicate that:(1) From the perspective of geographical features, the spatial distribution of As, Cd, Hg and Zn are mainly caused by enterprises which also are connected with the locations seriously polluted.(2) Under the condition of spare sampling, the spatial variability of heavy metals concentration can be better revealed by cokriging interpolation models, which also can achieve high spatial resolution mapping.(3) Prediction model can roughly reflect the change of soil heavy metal pollution with the time development trend, which also has a reference value of establishing reasonable soil heavy metal pollution prevention and control measures in the study area. (4) The results of the anthropogenic pollution show significant differences by using Index of Nemero and Pollution Load Index, the latter is relatively degree of stability with the results of the human health risk assessment, which can be more reasonably reflect the threat caused by human activities on soil environment security.(5) As and Cd cancerous risk are harmful to human health, nearly half of the region over the human cancerous risk criteria10times, which should take control measures.