Kinetic characteristics of heavy metals in soils in urban derelict contaminated land

Abstract

Despite being a hot topic for environmental management, heavy metal contamination in urban derelict industrial lands still lacks sufficient research into its kinetic parameters. This study aimed to systematically evaluate the contamination characteristics, labile fractions, lability, and solid-phase resupply kinetics of arsenic (As), cadmium (Cd), and lead (Pb) in various industrial soils using the Diffusive Gradients in Thin-films (DGT) technique, and to elucidate the regulatory mechanisms of key soil physicochemical properties. The results indicated that the heavy metal pollution risk in the soils of different types of derelict industrial sites exhibited significant industry-specific differences. Non-ferrous metal smelting (NMS) and steel coking (SC) sites not only showed severe exceedances in total heavy metal concentrations but also displayed characteristics of high lability (high CDGT) and rapid kinetic release (low Tc, high R). These areas are classified as high potential risk zones requiring priority control. Specifically, the acidic environment at the SC2 site exacerbated the active release of Cd. In contrast, chemical industry (CI) and coal mining (CM) sites primarily faced As pollution risk, but their release kinetic processes were relatively slow. This research identified priority sites with high environmental risks from heavy metals and confirmed the unique advantage of the DGT technique for potential risk assessment. The findings provide a critical scientific basis for developing availability-based remediation and management strategies.