ECOLOGICAL RISK ASSESSMENT MANAGEMENT METHODS OF HEAVY METAL POLLUTED URBAN GREEN LANDS

Soil heavy metal pollution is a key problem that threatens the ecological environment of urban lands. In the present research, the differences in soil phytoremediation effects under fertilizing, irrigation, and natural growth management methods in urban green land were explored. Poplus plant (Populus tremula L.) grown experimental urban green plots were established. Soils were collected to determine the concentrations of Cr, Ni, Cu, Zn, As, Cd, and Pb. The soil heavy metal pollution and ecological risk degree under different management methods were quantitatively analyzed by calculating single factor pollution index, Nemerow comprehensive pollution index, and geo-accumulation index, and potential ecological risk evaluation method. The results showed that there were two trends of heavy metal content with the increase in soil depth: one was gradually decreasing, the other was first decreasing and then increasing, and the minimum value was obtained at the depth of 20-40 cm. The Cd concentration in the test area showed light pollution, which was the main source of ecological risk. The order of management measures for soil heavy metal pollution remediation effect was fertilization, irrigation and natural growth. Fertilization and irrigation measures in urban green space were beneficial to the improvement of urban ecological environment quality and remediation of heavy metal pollution in urban green space soil.