Coupled iron and heavy metal accumulation in karst soils in Southwestern China: Iron isotope perspective

Heavy metals (HMs) are abundant in the karst soils of Southwest China, posing significant health risks to millions of people. Iron (Fe) (hyr)oxides serve as critical carriers of HMs in these soils; however, the processes governing Fe oxide formation and transformation associated with HM accumulation during carbonate weathering in karst region is less understood. In this study, we present Fe isotope compositions from a carbonate-derived profile to investigate the major factors controlling Fe migration. In the saprolite layer, strong correlations between δ