Geochemical Fractionation and Potential Ecological Risk of Cadmium and Lead in Soils Impacted by Secondary Lead Refinery.

Total and geochemical associations of Cd and Pb were studied on 75 topsoil samples around a small secondary metal recovery factory, which stopped operations in April 2006 due to metal environmental problems in surrounding communities. After a decade, we evaluated the potential ecological risk of Cd and Pb in impacted soils calculating the risk assessment code (RAC) and the risk index (RI) based on the Hakanson method. High concentrations of metals were found in soils around the factory, with dispersion pattern towards the north-west and south-east quadrants. Cadmium was predominant in exchangeable and carbonate fractions, while Pb was more associated to oxides, sulfides and in lesser extent to carbonates. The values of RAC and RI revealed a serious-considerable ecological risk in the surroundings of the land occupied by the factory and toward W-NW and SE. Statistical analyses showed that smelting activities had a great influence on the metals spatial distribution and their geochemical fractions in polluted soils.