Influence of suspended matter on cadmium accumulation in sediment from Ka tela Bay, Adriatic Sea, Croatia

Seasonal and spatial distributions of cadmium (Cd) and organic matter (OM) in sediment and suspended matter of the semi-enclosed Ka tela Bay (middle Adriatic Sea) were investigated at four stations during a one year period (April 2000 - April 2001). Samples of surface sediment and suspended matter were collected monthly. One sediment core was sampled at every station at the beginning of the sampling period. Cd concentrations in surface sediment and suspended matter were in the range of 0.082-0.904 mg kg-1 and 0.131-1.057 mg kg-1, respectively. The distribution pattern of Cd between sediment and suspended matter clarified Cd transport throughout the bay. The suspended matter acts as a collector and carrier of Cd in the bay. The higher concentrations in suspended matter were associated with lower concentrations in the sediments, which indicated that sediment resuspension has an important role in the distribution of Cd between sediments and suspended matter. The spatial distribution of Cd in the sediment and suspended matter of Ka tela Bay was in accordance with the prevailing circulation in the bay and indicated a partially anthropogenic origin of Cd. The vertical distribution revealed a decrease of Cd concentration with sediment depth, which also indicated an anthropogenic origin. Seasonal differences in the accumulation of Cd were recorded with concentrations being higher during the autumn-winter season, in accordance with a higher degree of sediment resuspension during this period.