Occurrence, Distribution, Sources, and Risk Assessment of Heavy Metals in Brownfields From Wuhan, Central China

Urban brownfields are abandoned industrial areas. They are generated as a result of land use transition in areas of rapid economic development within the urban context and are commonly contaminated with heavy metals and/or organics. Heavy metals lead to environmental degradation and functional degradation of the soil, thereby threatening the entire ecosystem. This work investigated the occurrence, sources, and risks of five target heavy metals in the old industrial city (Plots A, B, and C) of Wuhan. The heavy metal concentrations ranged from 0.02 to 253.00 mg/kg, and the dominant heavy metals were Hg, Pb, and Cu. Traffic emission/coal combustion and industry/natural/agricultural activities were identified as the main sources by the positive matrix factorization (PMF) model. The pollution load index (PLI), the potential ecological risk index (RI), and the geo-accumulation index (I_geo) results showed that Plot A had the highest soil risk, followed by Plots B and C. The carcinogenic effects on some sites of Plot A need to be considered. This work provides a theoretical basis for the assessment of heavy metal pollution and helps local governments to redevelop brownfields.