Impact of a zinc processing factory on surrounding surficial soil contamination

Zn smelting plants located at Auby (Northern France) have strongly polluted the surroundings through dust emissions, storage of ores and slag without strong environmental concerns. Although highly contaminated surficial soils have been removed in the private and public gardens to safeguard health of the inhabitants, one small public area, called the Peru Park, has not been treated because of the presence of peculiar calamine grasslands. Our investigations in the soils of this park clearly evidenced a very strong contamination by several metals with concentrations up to 21,000 mg kg− 1 for Zn, 3500 mg kg− 1 for Pb and 160 mg kg− 1 for Cd. Additionally, the mobility of these metals is important in soils and increases with the pollution level. In the pore waters of strongly polluted zones, our findings are more contrasted with high concentrations of dissolved Zn (3.6-32 mg L− 1) and to a lesser extent Cd (0.02-0.25 mg L− 1), whereas dissolved Pb remains at low concentrations (0.0001-0.021 mg L− 1) and, according to calculations, is quite exclusively bound to humic substances. Finally, this study obviously underlines that this severe pollution and the high mobility of Zn and Cd could strongly impact the surficial aquifer and the trophic chain present in this area.