Integrated model for heavy metal source tracing and multi-factor quantification, with risk assessment: A case study...

The heavy industry sector is a major source of gaseous pollutants, including heavy metals (HMs), which disperse beyond enterprise boundaries and contaminate surrounding soils. However, soil heavy metal source tracing and multi-factor quantification of cross-media transport remain insufficient. To address these research gaps, an integrated model for heavy metal source tracing in soil beyond enterprise boundaries and multi-factor quantification was developed, with a case study of a typical mega iron and steel enterprise in Tangshan, Hebei Province, China. The results indicated that the CALPUFF model can effectively capture the cross-media transport of heavy metals and identify the spatial distribution patterns of heavy metal hotspots. Moreover, distance from pollution sources, soil physicochemical properties, and atmospheric deposition had different influences on HMs because of the variability in the properties of different HMs, with atmospheric deposition identified as the primary factor affecting As and Ni. The integrated ecological risk index (with an average RI value of 87.12) reflected a low cumulative ecological risk, with Cd, Tl, and Pb identified as the priority contributors over the other heavy metals. The probabilistic health risk assessment revealed that Cr was the primary contributor to carcinogenic risk, accounting for 69.80 % of the risk in adult males, 69.40 % of that in adult females, and 64.10 % of that in children, whereas Tl and Cr were the two major elements responsible for non-carcinogenic risk. This study provides a scientific basis for characterizing the source-sink dynamics of heavy metals and quantifying their cross-media transport under multiple influencing factors, thereby supporting the development of more effective pollution control and environmental management strategies in heavy industries, particularly the steel sector.