Comprehensive risk assessment of cadmium and arsenic contamination in karst soils from high geological background areas

The study provides an in-depth assessment of the pollution risks stemming from cadmium (Cd) and arsenic (As) in the soils of the Guizhou Karst region. The aim is to offer critical insights for effective land management in these distinct geological settings.This study is based on 235 soil samples collected from woodlands and other areas in high geological background areas, and employed an enhanced fuzzy comprehensive evaluation method. This approach integrates four analytical models: the Pollution Index Method, Pollution Load Index, Potential Ecological Risk Assessment, and Human Health Risk Assessment, to quantitatively examine the ecological and environmental risks of Cd and As contamination. Findings indicate that Cd and As concentrations in the region markedly exceed national averages, highlighting a significant enrichment of these elements.Based on the Nemerow Pollution Index, 20.43% of the samples are classified as unpolluted, 45.96% as slightly polluted, 12.34% as moderately polluted, and 21.28% as heavily polluted.From the Pollution Load Index, the predominant category is slightly polluted, representing 43.83% of samples, with 21.28% classified under strong pollution contribution.The Potential Ecological Risk Assessment predominantly identifies slight ecological risks, encompassing 78.30% of the samples. Regarding human health risks, cadmium poses negligible non-carcinogenic threats to adults, whereas arsenic presents a higher non-carcinogenic risk to children.Although carcinogenic risks remain within acceptable limits for both demographics, the risk from arsenic exposure for children approaches levels of expert concern.By coupling the four evaluation models using fuzzy mathematics, the researchers categorize the soil environmental quality into four risk levels. These classifications guide the proposal of targeted land-use strategies, offering scientific recommendations for the adaptation of agricultural practices to local conditions in the Karst region.