Trace Metal Levels in Seawater, Suspended Particulate Matter and Sediment in Mersin Bay, Turkey

The concentrations and distributions of trace metals in surface sediment, water and suspended particulate matter (SPM) in coastal area of Mersin Bay were studied to determined the anthropogenic inputs from surrounding activities. Elevated zinc levels (275 ppm) represent the trace metal with the highest concentration, as measured in suspended particulate matter samples collected from the Kazanlı and Karaduvar areas. The high concentrations are associated with terrestrial inputs from the anthropogenic (domestic +industrial) sources. An important observation is that increasing concentrations are found in dissolved phase, sediment and particulate phase, respectively. But this is not the case for Cr which is higher in sediment. This is related to intense activity of chromium processing plant working for many years. Moreover, Cd and Cr concentrations in surface sediments are above the shale average. Heavy metal concentrations in surface sediments are Cr>Zn>Cu>Pb>Cd, respectively. The elevated copper level relative to cadmium in surface sediments is likely attributable to the higher stability of surface complexes with clay minerals, which constitute the primary components of the sediments. Adsorption of zinc to iron and manganese oxide compounds in the sediment is a possible explanation for the high amounts of zinc that were found in the sediments. The estimated index values (enrichment factor, geoacumulation index and pollution load index) indicated widespread contamination of Cr and Cd in Mersin Bay. The origins of these trace metals in the sediments were caused by human activity, and the region was categorized as a moderately severely polluted area.