engleski

Detection of geochemical anomalies in stream sediments of the upper Sava River drainage basin (Slovenia, Croatia)

Sava River is a transboundary river of supra-regional interest, draining 95, 719 km2 in Slovenia, Croatia, Bosnia and Herzegovina, and Serbia. It is a typical Alpine river, flowing from Julian Alps. On entering Croatia, it becomes a typical lowland river. The possible influence of sediments of the sub-basins of Savinja, Krka and Kupa rivers on the sediments of the main course of Sava River was studied. Mineralogical composition was determined by X-ray diffraction (XRD), and chemical composition by inductively coupled plasma mass spectroscopy (ICP-MS). Two differ-ent procedures to identify anomalous geochemical data, the box plot method and the median absolute deviation (MAD), were used. Results obtained by the box plot method showed that anomalous concentrations (extremes or outliers) of Zn, Pb, In, Cu, Co, Se, Zr, Cd, As, K, Na, Tl, Ba, B, Mn, and Fe are present in sediments of the Celje region, as well as of Cr, Ni, S, In, Cu, Mo, Pb in Moste dam (pollution traced down to Camping Šobec), and of Hg in Litija-Zagorje min-ing region. The MAD method is more sensitive, and depicts the same polluted areas, but with more anomalous values, which are above threshold values for toxicity. The results of the selected toxic elements, with concen-trations limiting the quality of freshwater sediments, are particularly discussed. Both statistical methods (box plot detection method and MAD method) show two anomalous values for Hg in Sava River near Kranj and Zagorje. The concentrations are much higher than those causing signifi-cant toxic effects >>2 ppm. Two locations of Sava River in Croatia (Strelečko and Lukavec Posavski) show a very clean environment with respect to trace elements, although Sava River passed big cities of Zagreb and Sisak. The re-sults clearly indicate self-purification mechanisms of Sava River. A similar future sediment study is recommended on middle and lower Sava drainage basin, of interest for Croa-tia, Bosnia and Herzegovina and Serbia, to detect possible pollution centers. In the case of significant pollution, reme-diation measures should be applied to improve sediment quality and management.

chemical composition; geochemical anomalies; mineral composition; pollution; Sava River; self-purification; stream sediments

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