Spatiotemporal simulation, early warning, and policy recommendations of the soil heavy metal environmental capacity of the agricultural land in a typical industrial city in China: Case of Zhongshan City

Abstract

Soil environmental capacity and risk warning are the core contents of soil security research. In this study, geostatistical analysis, a material balance linear model, and an environmental load capacity method were selected to simulate the environmental capacities of eight heavy metals (Hg, As, Cr, Cu, Ni, Pb, Zn and Cd) in the agricultural land of north Zhongshan City. Then, based on the capacity data in 2015 as the baseline year, risk early warning assessment was carried out, and the management strategy of soil heavy metal pollution under the goal of “soil security” was proposed accordingly. The results showed that between 2015 and 2035, there was a 1.73-fold increase in the average annual capacity of heavy metals in the soil samples collected in the study area. Generally, the heavy metal environmental capacities showed an upward trend, except for Hg, and the low capacity areas were primarily distributed in the northern plain. The comprehensive risk level was medium, based on the soil heavy metal environmental capacities. Further, the average environmental capacity indexes of Hg, As, Cr, and Pb were all >1, corresponding to no risk. However, those of Ni and Zn were 0.8 and 0.7, which corresponded to mild risk, while those of Cu and Cd were all <0, corresponding to extreme risk. Additionally, it is necessary for the government to consider the main pollution sources when formulating targeted measures aimed at controlling agricultural land heavy metal pollution in industrial cities. The results of this study provide theoretical contributions on early warning of risks related to heavy metal environmental capacity of the agricultural land in industrial cities, and serve as practical reference for speeding up the formulation of agricultural land pollution management policies.