Pollution characteristics and ecological risk apportionment at a smelting site based on stochastic simulation

Geostatistical analysis and Pb isotope tracing were used to characterize the distribution patterns and the sources of heavy metals at a lead smelting site. Furthermore, ecological risks were apportioned based on stochastic theory. The results showed that soils were seriously contaminated by Pb, Zn, As, Cd, Cr and Hg, which reflected strong spatial heterogeneity. Based on MixSIAR model, the density distributions of three endmembers were deconstructed, in which 49.9% of Pb came from smelting activities, and 16.4% and 33.7% from coal combustion and geological source, respectively. Along with the integration of the apportionment of Pb isotope and Monte Carlo simulation, concentration-oriented probabilistic risk indicated that the moderate risk level was dominant, and Cd, As, Pb and Hg were sensitive factors. Source-oriented probabilistic risk presented that smelting contributed the most to risk accumulation. Therefore, the control of Cd, As, Pb and Hg and the disposal of potential smelting sources should be in priority.