Metal and organic carbon distribution in water column of a shallow enclosed Bay at the Aegean Sea Archipelago: Kalloni Bay, island of Lesvos, Greece

Metals and organic carbon concentrations in dissolved and particulate phases were determined seasonally (wet and dry periods) in four different sites of the semi-enclosed shallow marine system of Kalloni Bay in the island of Lesvos, Greece. The Bay is a typical system of many Mediterranean islands, which combine intermittent stream discharges, lengthy dry periods and relatively light anthropogenic activities on the coastal zone and the study aimed at the investigation of heavy metal partitioning mechanisms under such conditions. Seasonal and spatial variations in metal concentrations showed that fluvial transport is the major pathway for Cu, Fe, Ni and particulate Al and Li to the Bay. Wet deposition during winter probably determines the distributions of Pb and Zn. Manganese distribution appears to be regulated by diagenetic processes in the sediment, leading to Mn release in the overlying water column. Lithium is transported in the very fine fraction of suspended particulate matter (SPM) and is uniformly distributed in the area. Dissolved phase is the major metal carrier for Cd, Cu, Ni, Pb and organic carbon, while Fe and Mn are mainly transported in the particulate phase. Important spatial variations in metal partitioning were observed only for Ni because of the presence of nickeliferous ultrabasic minerals at the Northeastern part of the Bay. The concentrations of the human related metals (Cd, Cu and Zn) were low indicating very small anthropogenic influence in the area. The concentrations of organic carbon in dissolved (DOC) and particulate (POC) phases were regulated by primary production as well as fluvial transport and were similar to enclosed eutrophic systems or estuaries.