Evaluation of Sediment Contamination by Heavy Metals, Organochlorinated Pesticides, and Polycyclic Aromatic Hydrocarbons in the Berre Coastal Lagoon (Southeast France)

Abstract

During the last decades, the Berre lagoon, located in southeastern France, has been deeply affected by strong contaminant inputs. Surveys of surface sediment contamination have been sparsely performed since 1964 with data often disconnected with regard to time and space. To contribute to filling this gap, this study examined the pollution status of the lagoon during a 2012 sampling. Concentrations of heavy metals (HMs) (cadmium [Cd], chromium [Cr], copper [Cu], lead [Pb], and zinc [Zn]), organochlorine pesticides (OCPs), and polycyclic aromatic hydrocarbons were examined. The available seawater metal fraction was also investigated. Water from the Vaine basin (VB; stations 1 through 6) exhibited the lowest oxygen concentration (mean O₂ % saturation 38.9 %). HM loads were in the order of Zn > Cr > Pb > Cu > Cd with overall concentration ranges of 0.20–1.40 mg kg⁻¹ for Cd, 17.1–119 mg kg⁻¹ for Cr, 7.0–60.7 g⁻¹ for Cu, 12.0–104 mg kg⁻¹ for Pb, and 56.5–215 mg kg⁻¹ for Zn. Although HMs accumulated at levels largely exceeding their relative natural background level of 11-fold for Pb and 80-fold for Zn, their mean concentrations decreased largely to below the acceptable legal limits. HM loads were 20 to threefold the relative corresponding value of the threshold effect level benchmark of potential biological risk. Metals were only scantly released by sediments with mean percentage release of 0.99 % for Cd and 40.2 % for Cr with a peak for this latter element of 99 % in the VB sector. In the case of OCPs, sediments appeared to be significantly polluted, especially in the VB area, with a mean lindane concentration of 0.05 mg kg⁻¹, which is ≤fivefold the legal threshold. Among PAHs, benzo[a]pyrene exceeded the permitted limit of 0.1 mg kg⁻¹ mainly in the VB sector.