Study on the factors affecting the spatial distribution of heavy metal elements

Abstract

The contents of As, Cr, Cu, Zn and Pb in soils of the central urban area of Nanjing Jiangbei New area are analyzed by interpolation analysis. The effects of pH value, soil texture and heavy metal species on the contents of heavy metals are studied. The results show that the contents of heavy metals in the study area are more than 1.5 to 6.3 times of the soil background value in Jiangsu Province. The content of heavy metal Cr is 31.92∼95.38 mg/kg, and some areas have already exceeded the control value of the second type of construction land in China, 78 mg/kg. The pH value is inversely proportional to the total heavy metal content, which indicates that it is more difficult to enrich heavy metal ions in alkaline environment. The soil texture in this area is dominated by sand grains, and the spatial distribution of sand grain content decreases from southwest to northeast. The clay content is positively correlated with the heavy metal content except Zn. The main forms of the five kinds of heavy metals in soil are residues, reaching 73.86%∼88.15%, and with the increase of heavy metals content in soil, the proportion of residual decreases.