Risk-based assessment of multimetallic soil pollution in the industrialized peri-urban area of Huelva, Spain

The peri-urban soils of Huelva, one of the first industrial cities in Spain, are subject to severe pollution problems primarily due to past poor management of industrial wastes and effluents. In this study, soil cores were collected in seven sites potentially contaminated with toxic chemicals arising from multiple anthropogenic sources, in order to identify trace elements of concern and to assess human health risks associated with them. In most soil core samples, total concentrations of As (up to 4,390 mg kg−1), Cd (up to 12.9 mg kg−1), Cu (up to 3,162 mg kg−1), Pb (up to 6,385 mg kg−1), Sb (up to 589 mg kg−1) and Zn (up to 4,874 mg kg−1) were by more than one order of magnitude greater than the site-specific reference levels calculated on the basis of regional soil geochemical baselines. These chemicals are transferred from the hazardous wastes, mainly crude pyrite and roasted pyrite cinders, to the surrounding soils by acid drainage and atmospheric deposition of wind-blown dust. Locally, elevated concentrations of U (up to 96.3 mg kg−1) were detected in soils affected by releases of radionuclides from phosphogypsum wastes. The results of the human health risk-based assessment for the hypothetical exposure of an industrial worker to the surface soils indicate that, in four of the seven sites monitored, cancer risk due to As (up to 4.4 × 10−5) is slightly above the target health risk limit adopted by the Spanish legislation (1 × 10−5). The cumulative non-carcinogenic hazard index ranged from 2.0 to 12.2 indicating that there is also a concern for chronic toxic effects from dermal contact with soil.