| Popis: |
PCBs, due to their low solubility in water and hydrophobic nature, show a strong affinity for particulate matters in aquatic ecosystems. Besides an available large surface area, the organic content of a particle is of primary importance for the PCBs adsorption. The sediments of estuarine and coastal areas, therefore are considered as a good indicator of PCBs presence in the marine environment. In order to assess the level of contamination of coastal waters of the middle and south Adriatic by PCBs, six individual PCB congeners (28, 52, 101, 118, 138 and 153) were selected for this investigation. For this purpose, surface sediment samples (0– 2 cm) were collected with a Van Veen grab at 7 stations in the "inner shore" waters and at one station in "off shore" waters in October 2004. The PCBs concentration in the surface sediments ranged from 0.22 to 31.23 ng/g dry wt. The lowest concentration was found at the "off shore" referent station Stoncica, indicating the absence of antrophogenic influence at the investigated area. The highest concentration was obtained at the area of the Kastela Bay (Split), as the result of long-term urban and industrial wastewaters discharges into the bay. The most abundant higher chlorinated congeners PCB 138 and PCB 153 were present at higher concentrations in the entire investigated area. However, the congeners with a lower chlorination degree (PCB 28, PCB 52) occured at low concentration levels, most probably due to their slightly higher water solubility. The obtained results showed that the PCBs concentration in the sediments depends primarily on local pollution sources, environmental characteristics as well as on the geology of the surrounding terrestial environment. |
