Exploring the spatio-temporal dynamics and driving mechanisms of toxic metal pollution in soil using a hybrid machine learning-based model

Understanding the spatio-temporal dynamics and key drivers of toxic metal pollution in soil is crucial for effective pollution control and human health protection. In this study, we characterized the dynamics of toxic metals (Cd, Hg, As, Pb and Cr) pollution from 2012 to 2022. Moreover, the pollution sources, associated health risks, and their spatio-temporal dynamics along with key drivers were analyzed using a hybrid machine learningbased model integrates multisource environmental data. The results showed that the Cr and As contents in soils increased markedly from 2012 to 2022, affecting approximately 90 % and 67 % of the samples, respectively. Industrial and agricultural activities were the main sources of the increase in Cr (contributing 34.44 %-37.60 %) and As (contributing 27.24 %-28.07 %), respectively. Children faced the greatest health risks from ingestion, with As and Cr accounting for more than 80 % of the total risk. In addition, industrial activities posed the greatest health risk (contributing 44.33-71.97 %), followed by agricultural activities (contributing 16.08-40.08 %). Areas with strong industrial health risks were clustered in the northern industrial zones and eastern coasts and showed an increasing trend in each region, which was driven primarily by intense anthropogenic activities, particularly mining activities. Areas with strong health risks from agricultural activities were concentrated in the eastern coastal plains and generally exhibited a decreasing trend This research revealed increased risks from toxic metal contamination, with important implications for human health.