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Natural and anthropogenic influences recorded in sediments from the Krka river estuary (Eastern Adriatic coast), evaluated by statistical methods

Surface sediments and cores from the Krka river estuary (Eastern Adriatic coast) were analyzed for their trace-element composition by means of HR ICP-MS (High Resolution Inductively Coupled Plasma Mass Spectrometry). Various statistical analyses were used to evaluate the geochemical composition of these sediments and to establish the degree of anthropogenic influence to the Krka river estuary. Statistical analysis showed clear anthropogenic influence on several spots of the Krka river estuary. Sediments sampled in the Šibenik port demonstrated the highest concentrations of ecotoxic metals as being Cd (34.4 mg/kg), Zn (4010 mg/kg), Pb (253 mg/kg), As (45.3 mg/kg) and Cu (24.6 mg/kg). Calculated Müller’ s geoaccumulation index (Igeo) values, after normalization on average carbonate values are for Cd (4.7), Zn (6.9), Pb (4.2), As (5.5), Cu (2.0). Igeo values after normalization on average shale are for Cd (6.3), Zn (4.9), Pb (3.1), As (1.6), Cu (1.6). It suggests moderately to heavily polluted Šibenik harbor. The pollution source at this location results from long-term phosphate ore unloaded at the port as well as input of untreated wastewaters from the city of Šibenik. Another contaminated area was established in front of the now closed ferromanganese factory, with maximum measured concentrations of Mn (2526 mg/kg), Pb (143 mg/kg) and Ba (255 mg/kg). However, in the major portions 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 majority portions of the Krka river estuary is still unpolluted.

Krka river estuary; Eastern Adriatic coast; sediment; metals; anthropogenic influence; statistical analysis

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