Assessment of heavy metal contamination and ecological risk in agricultural soils near industrial areas

Abstract

Imagine a farmer discovering that the topsoil 300 metres from a steel plant contains nearly ten times the safe level of cadmium. This research assessed Cd, Pb, Zn, Cu, and Cr concentrations in agricultural soils at four distance zones (0-500, 500-1000, 1000-2000, 2000-5000 m) from an industrial complex near Uppsala, Sweden, using the Hakanson potential ecological risk index. A total of 48 composite soil samples were collected across three transects in 2022-2023. Cd concentrations at 0-500 m (3.84 mg/kg) exceeded Swedish guideline values by 9.6×. The integrated ecological risk index (RI) was 312 at 0-500 m (very high risk) and dropped to 86 beyond 2000 m (moderate). Cd alone contributed 68% of total risk. Contamination was negligible beyond 2000 m, establishing a clear spatial boundary for remediation priorities.