engleski

Krka river estuary (Eastern Adriatic Coast) – evaluation of natural and anthropogenic influences by multielemental analysis

Krka river estuary (Eastern Adriatic Coast) – evaluation of natural and anthropogenic influences by multielemental analysis N. Mikac*, N. Cukrov and G. Kniewald Division for Marine and Environmental Research, Rudjer Bošković Institute, 10000 Zagreb, Croatia * E.mail: mikac@irb.hr The Krka River estuary is located on the Eastern Adriatic coast and is typical karstic highly stratified estuary with fresh/brackish surface layer flowing seawards and bottom seawater counter-current moving upward. Estuary has a total length of 22 km with a water depth which gradually deepens from 2 m to 42 m. Input of terrigenous material into the Krka river estuary is relatively small and prevented by the number of calc tufa barriers at the river/estuary boundary. The uniqueness of these tufa barriers and so formed waterfalls was the base for the proclamation of this area as a National Park. In the central part of the estuary the town of Šibenik (40000 inhabitants) is located. The sources of the anthropogenic pollution in the estuary were disembarking of the phosphate ore in the Šibenik port, the input of untreated wastewaters from the city of Šibenik and the ferromanganese factory located near the town of Šibenik. All these sources of pollution are now closed. Previous work established localized pollution with some elements (Hg, Mn, U, ref. 1, 2, 3), but assessment of the contamination of the entire area of the Krka river estuary with a variety of eco-toxic elements was never performed. The aim of the work was to establish degreed of anthropogenic influences in the estuary by the multielemental analysis of sediment and water. Surface sediments and sediment cores as well as surface water were analyzed for trace element composition by means of the HR ICP-MS (High Resolution Inductively Coupled Plasma Mass Spectrometry). Analysis showed a clear anthropogenic influence on several spots of the Krka river estuary. The most severe pollution was established in the Šibenik port for elements Hg, Cd, Zn, Pb, As and Cu and was ascribed to a combined pollution from disembarking of the phosphate ore and input of untreated municipal wastewaters. Another contaminated spot was established in front of the closed ferromanganese factory with maximum measured concentrations of Mn, Pb and Ba. However, in the largest part of the Krka river estuary concentrations of measured elements were low and varied only due to natural (lithogenic and marine) influences. This indicates that the major part of the Krka river estuary is still unpolluted. References 1. Mikac N., Roje, V., Cukrov, N. and Foucher, D. (2006) Mercury in aquatic sediments and soils from Croatia. Archives of Industrial Hygiene and Toxicology. 57, 3, 325-332. 2. Oreščanin, V., Barišić, D., Mikelić, L., Lovrenčić, I., Rubčić, M., Rozmarić-Mačefat, M. and Lulić, S, (2004) Environmental Contamination Assessment of the Surroundings of the ex-Šibenik’s Ferro-manganese Smelter, Croatia. Journal of Environmental Science and Health, Part A-Toxic/Hazardous Substances & Environmental Engineering, A39, 9, 2493-2506 3. Cuculić V, Cukrov N, Barišić D, Mlakar M. (2006) Uranium in sediments, mussels (Mytilus sp.) and seawater of the Krka river estuary. J Environmental Radioactivity 85, 59-70.

Sediment ; trace metals ; pollution ; Krka river

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