Ecological and Health Risks of Thallium in Weathered Granite Soils <?A3B2 pi6?>of Southern China

<p indent="0mm">Thallium (Tl), as a non-essential heavy metal element, exhibits toxic effects to animals, plants, and humans. In nature, Tl primarily occurs in low-temperature hydrothermal sulfides and potassium-containing silicate minerals. The weathering of granite, as a particularly important carrier of potassium silicate minerals, may promote the dissolution of these minerals, thereby releasing Tl into the surface environment and leading to its high background level. Noticeably, granites from different geological periods contain varying amounts of potassium silicate minerals and sulfides. However, a comprehensive understanding of whether these differences are directly related to the ecological risks of Tl and other heavy metals in soils, and the potential health risks that may arise, is still lacking. This study focused on the weathered soils of Triassic and Jurassic granites in South China, exploring the ecological risks and potential health risks of Tl and its key controlling factors. The results show significant differences in Tl content and ecological risk indices between the weathered soils of Triassic and Jurassic granites. Additionally, the absorption and accumulation capabilities of crops planted in weathered soils from different granite periods vary significantly, leading to differences in Tl health risk indices. Random forest analysis indicates that the ecological and health risks of Tl in weathered granite soils are primarily influenced by the distribution of Tl, potassium (K), and phosphorus (P) in the soil. These distribution differences are constrained by the chemical composition of the weathered soils from the two different granite periods. These findings provide novel insights into the geochemical behavior of heavy metals in high geological background areas, contributing to a more comprehensive assessment of environmental and health risks and facilitating the implementation of appropriate management measures.