Distribution of heavy metals in sediment cores of Lake Pamvotis (Greece): a pollution and potential risk assessment.

Concentrations and vertical distributions of metals in surface sediments of Lake Pamvotis (NW Greece) were assessed using energy-dispersive X-ray fluorescence spectrometry. A wide range of values was determined, associated with the specific types of contaminating effluents draining into different parts of the lake. Overall, Cr levels ranged from 43 to 3295 mg kg(-1), Ni from 13 to 372 mg kg(-1), Cu from 15 to 24,985 mg kg(-1), Zn from 129 to 22,983 mg kg(-1), Zr from 64 to 4063 mg kg(-1) and Pb from 19 to 2634 mg kg(-1). Principal component analysis revealed distinct elemental fingerprints in each sampling location, while correlation analysis and hierarchical agglomerative cluster analysis provided insight to metal association and pollution sources. Enrichment factors and geoaccumulation indices were calculated to quantify sediment contamination, and potential ecotoxic effects were evaluated based on sediment quality guidelines. Moderate to very severe enrichment in Zn, Cu and Pb was evidenced in sediments near the lake's outflow. The proximity of these sampling points to a heavy traffic national road suggests that roadway runoff is the dominant source of elevated metal levels. Contribution from municipal sewage water discharges from the nearby communities should also be accounted for. Moderate to very severe Zn and Pb enrichment was determined in the vicinity on the main lake's inflow, primarily associated with runoff and leaching from agricultural land. Very severe to extremely severe Cr enrichment was detected in the same location, most likely associated with wastewater discharged into the lake over several decades, by nearby-operating leather tanneries. The above two locations were ranked at the highest priority level in terms of potential ecological risk.