Search

Purpose: The overexploitation of resources such as mining and metallurgical and agricultural resources has resulted in heavy metal accumulation and soil acidification. Studying the spatial distribution, food chain translocation, human health risks, and environmental thresholds of heavy metals in agroecosystems is essential for the management and mitigation of soil degradation and heavy metal contamination. Materials and methods: In this study, we investigated an extensive maize-growing area at the core of Asia's largest karst region, which has been strongly influenced by historical nonferrous metal smelting activities. We collected a total of 164 crop and 164 soil samples within the study area via the chessboard sampling method. Inductively coupled plasma mass spectrometry (ICP) was used to quantify 4 heavy metals (Pb, Cd, Cr, and As). The spatial distributions of these heavy metals were simulated using statistical methods, and the spatial relationship between food chain translocation of these heavy metals and the soil pH, as well as the potential health risk and soil environmental threshold in the research area, was obtained. Results and discussion: The soil in the research area exhibited high accumulation of heavy metals Cr (131.40 mg kg−1) and Pb (94.19 mg kg−1), followed by As (25.86 mg kg−1) and Cd (2.39 mg kg−1). In addition, Cd, Pb, and Cr translocation in the soil-maize system exhibited a significant negative correlation with the soil pH. Health risks were significantly higher in areas with low pH and high heavy metal levels in the soil, and the risks were significantly higher among children than those among adults. Moreover, the National Ecological Environment Criteria Calculation Software-Species Sensitivity Distribution (EEC-SSD) method was proposed to derive soil environmental thresholds: 3.8–47.0 mg kg−1 for Cd, 177.1–730.5 mg kg−1 for As, 160.1–1554.9 mg kg−1 for Pb, and 113.8–436.2 mg kg−1 for Cr. Conclusions: In this study, the spatial distributions of Pb, Cd, Cr, As, and soil pH values in a historical Pb–Zn smelting and coal mining area were obtained. The spatial relationship between food chain translocation of the considered heavy metals and the soil pH was determined. In addition, the proposed EEC-SSD model could provide a valuable tool to assess the soil quality in local agricultural land under maize cultivation. [ABSTRACT FROM AUTHOR]