Ecological risks assessment of heavy metal coupled inorganic sulfur characteristics in the sediments of the Qinjiang River, Beibu Gulf, China

The relationship between sulfur concentration and heavy metals in sedimentary environments is complex, significantly affecting ecological processes and posing environmental risks. This study aimed to evaluate the ecological risks associated with acid volatile sulfur (AVS), chromium-reduced sulfur (CRS), elemental sulfur (ES), and various heavy metals such as zinc (Zn), copper (Cu), chromium (Cr), lead (Pb), and cadmium (Cd) in sediment samples from the Qinjiang River in the Beibu Gulf region of Guangxi, China. The study employed SEM/AVS ratio and SEM-AVS difference methods, in conjunction with sediment physicochemical properties. The results indicate that AVS is predominant in surface sediments, with concentrations increasing downstream. Additionally, SEM revealed several peaks across the river, likely attributable to various human sources such as farming practices, coal burning, and emissions from vehicles and ships. This study provides a theoretical foundation and reference data for understanding the geochemical behaviors of inorganic sulfur and heavy metals.