Large-Scale Spatiotemporal Risk Assessment Method Based On Source–Pathway–Receptors: A 30-Year Case Study of Nonferrous Metal Industrial Sites

Most existing risk assessment methods lack the capability to conduct large-scale analysis and accurately evaluate long-term trends. To solve this problem, this study integrated various methodologies, including analytical hierarchy process model, multicriteria decision analysis techniques, and spatial analysis, to conduct a comprehensive risk assessment based on sources, pathway, and receptors. With the aim of quantifying the spatiotemporal risk of nonferrous metal industrial sites in China from 1990 to 2020, this study performed hazard, vulnerability, and risk factor analyses to explore the trend of risk changes and reveal the effectiveness of pollution control efforts. Results showed that the potential risk of nonferrous metal industrial sites exhibited nonlinear changes, increasing from 13.49% in 1990 to 16.41% in 2000, peaking at 23.17% in 2010, and then declining to 19.06% in 2020. Moreover, with the increasing number of contaminated sites, the spatial distribution of potential risks showed pattern of dispersion followed by concentration, with lower risks in most areas. Finally, spatiotemporal risk variations were considerably affected by source-smelting and mining, pathway-wind and surface runoff, and receptor-socioeconomic development and population agglomeration. The proposed methodology can help decision-makers identify specific risk areas and patterns of variation over long-term scales and large-scale regions.