Multi-seasonal assessment of soil contamination and metal mobility following the Jagersfontein tailings storage facility failure event in South Africa

The failure of the Jagersfontein tailing storage facility (TSF) in South Africa on 11 September 2022 released ~5.8 million m 3 of kimberlite tailings into a semi-arid wetland, representing one of the largest such spillages in history. This study investigates the chemical evolution of the deposited tailings and their impact on soil geochemistry over three seasons (18 months). Geochemical and statistical analyses identified two broad elemental groupings: Group 1 elements (B, Na, Mg, Cr, Mo, Co, and Ni) were primarily introduced into the landscape by the tailings, whereas Group 2 elements (V, Mn, Cu, Zn, As, Sn, Cd and U) were mainly enriched through landscape-driven processes, particularly groundwater discharge, and material redistribution during flood events. Sodium migrated rapidly through the soil profile, contaminating soils down to bedrock, and showed no signs of recovery even where surface tailings had been removed. In contrast, Mg, Cr, Co and Ni migrated primarily via colloidal-facilitated transport, resulting in the progressive enrichment of the upper soil horizons. The tailings' sodic and metal-laden nature is particularly problematic in an environment naturally enriched in Na, B, As and Mo. Chemical mass transfer analyses indicate that pedogenic processes are unlikely to reverse contamination within ecologically meaningful timescales. Immediate remediation, including tailings removal, is recommended to mitigate long-term environmental and health impacts. Overall, the findings demonstrate that environmental impacts extend far beyond surface contamination, revealing complex subsurface enrichment pathways that offer new insights into contaminant behaviour following large-scale tailing failures in dryland environments.