Detection of Geochemical Anomalies in Stream Sediments of the Upper Sava River Drainage Basin (Slovenia, Croatia)
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© by PSP Volume 17 – No 2. 2008 Fresenius Environmental Bulletin DETECTION OF GEOCHEMICAL ANOMALIES IN STREAM SEDIMENTS OF THE UPPER SAVA RIVER DRAINAGE BASIN (SLOVENIA, CROATIA) * Stanislav Frančišković-Bilinski Institute “Ruđer Bošković”, POB 180, 10002 Zagreb, Croatia ABSTRACT Sava River is a transboundary river of supra-regional pollution centers. In the case of significant pollution, reme- interest, draining 95,719 km2 in Slovenia, Croatia, Bosnia diation measures should be applied to improve sediment and Herzegovina, and Serbia. It is a typical Alpine river, quality and management. 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. KEYWORDS: chemical composition, geochemical anomalies, mineral composi- Mineralogical composition was determined by X-ray tion, pollution, Sava River, self-purification, stream sediments. 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), INTRODUCTION were used. The Sava River is a transboundary river, with a length 2 Results obtained by the box plot method showed that of about 1.000 km. It drains an area of 95.719 km in Slo- anomalous concentrations (extremes or outliers) of Zn, Pb, venia, Croatia, Bosnia and Herzegovina, and in Serbia. 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 The river flows into the Danube River at Belgrade (Ser- Cr, Ni, S, In, Cu, Mo, Pb in Moste dam (pollution traced bia). The geochemical composition of the related stream down to Camping Šobec), and of Hg in Litija-Zagorje min- sediments is not well-known, because a limited number of ing region. The MAD method is more sensitive, and depicts elements was studied so far. Štern and Förstner [1] de- the same polluted areas, but with more anomalous values, scribed the heavy metal distribution in the sediments of which are above threshold values for toxicity. the Sava basin in Slovenia. They found two pollution cen- ters, one in the Sava River, near to the Moste power plant The results of the selected toxic elements, with concen- (close to Jesenice) with high concentrations of Zn, Pb, Cd, trations limiting the quality of freshwater sediments, are Hg. The other pollution center is in the Savinja River (tri- particularly discussed. Both statistical methods (box plot butary of the Sava River), in the Celje district with high detection method and MAD method) show two anomalous concentrations of Cr, Zn, Cu, Pb, Cd. A preliminary report values for Hg in Sava River near Kranj and Zagorje. The of the state of sediments in the upper Sava River (section concentrations are much higher than those causing signifi- of about 380 km downstream from Zelenci, Sava Dolinka cant toxic effects >>2 ppm. Two locations of Sava River in source to Lukavec Posavski, after Kupa River inflow) has Croatia (Strelečko and Lukavec Posavski) show a very shown an almost unpolluted environment. Only a site at the clean environment with respect to trace elements, although Camping Šobec, situated about 10 km downstream from Sava River passed big cities of Zagreb and Sisak. The re- the pollution center of Moste power plant, gives evidence sults clearly indicate self-purification mechanisms of Sava for environmental pollution [2]. According to Kotnik et River. al. [3], the stream sediments in Moste are polluted by Cd, Cr, Cu, Ni, Pb and Zn. Sediments of the polluted Celje A similar future sediment study is recommended on district were studied in detail by Frančišković-Bilinski et middle and lower Sava drainage basin, of interest for Croa- al. [4, 5]. Attic dust and soil of this region, as complemen- tia, Bosnia and Herzegovina and Serbia, to detect possible tary sampling media, were investigated by Žibret [6] and 188 © by PSP Volume 17 – No 2. 2008 Fresenius Environmental Bulletin Šajn [7]. Accordingly, the Celje region is still contami- course of the Sava River from its source in Zelenci (Slo- nated, particularly with Zn and Cd. The contamination is venia) down to Lukavec Posavski (Croatia), after the Kupa not dissipated in the lower flow of the Savinja River, sav- River inflow. Geochemical anomalies and, especially, an- ing the river, as concluded from box plot method [5]. Sedi- thropogenic pollution sites are detected by alternative meth- ments of the Sava River in Croatia were studied less in- ods and discussed in comparison to former works. It is ex- tensively. Halamić et al. [8] studied the heavy metal distri- pected that the obtained results will be a contribution to bution in the topsoil over alluvial sediments in NW Croatia. EU legislation on soil and sediment protection. With the exception of higher Hg contents in the city of Zagreb, the Sava River valley in NW Croatia shows no anomalous values of heavy metals. Oreščanin et al. [9] have MATERIALS AND METHODS studied the influence of the Krško nuclear power plant downstream to Zagreb in size-fractionated Sava River Study area sediments. The concentrations of 13 investigated elements The sampling locations of the study area cover the (K, Ca, Ti, Cr, Mn, Fe, Cu, Zn, Rb, Sr, Y, Zr, Pb) indicate Sava River drainage basin within Slovenia (together with that the examined Sava River sediments do not constitute two large sub-basins of Krka and Savinja rivers), and also an environmental problem. Pavlović et al. [10] studied the two sampling points downstream in Croatia, near Sisak impact of the former Pb-Zn-Ba mining activities in Slo- (one before and one after Kupa River inflow). The details venia on overbank sediments of the Sava River in Croatia of each sampling location, name of the rivers, name of and concluded that the studied overbank profiles were af- locality, geographic coordinates (X, Y), together with the fected by the former mining activities. Van der Meulen et anomalies at each location are presented in Table 3. al. [11] have studied the sulphate sources in the Sava and Ljubljanica rivers, and found that they contain sulphates The geology of Slovenia is of high diversity [12]. of different sources. Using solution data, they found no Therefore, geologic setting of the studied area is presented evidence for the introduction of sulphate from factories into in a simplified geological map showing locations of sam- rivers. pling points (Fig. 1). It is based on Geological Map of SFR Yugoslavia 1:500000, sheet Zagreb. To take the geochemi- The database available till now is insufficient to accu- cal signature of the river sediments into account, 6 litho- rately delineate the geochemical anomalies within the Sava types (unconsolidated Miocene-Pliocene sediments, mag- River drainage basin. The objective of this research is, matic rocks, Eocene flysch sediments, Paleozoic meta- therefore, to extend the data set and to study the possible sediments, Mesozoic carbonate rocks and Quaternary influence of sub-basins of Savinja, Krka and Kupa rivers sediments) are considered. The details about geological on the geochemical and mineralogical status of the main setting of Slovenia and Croatia can be found in [13] and [14]. FIGURE 1 - Simplified geological map of the studied area. The main right tributaries of Sava River are Sora, Ljubljanica, Krka and Kupa. The main left tributary of Sava River is Savinja with its tributaries Voglajna and Hudinja. Coordinates and detailed description of sampling localities are presented in Table 3. 189 © by PSP Volume 17 – No 2. 2008 Fresenius Environmental Bulletin The Sava River springs in Zelenci, where the geology Chemical analysis of 56 elements was performed by is dominated by Mesozoic carbonate rocks. In the middle the ACTLABS laboratory (Ontario, Canada), using the part, the Sava River drains Quaternary sediments, whereas Inductively Coupled Plasma Mass Spectroscopy (ICP-MS) its lower parts are dominated by Mesozoic to Cenozoic program “Ultratrace 2”. In this procedure, 0.5 g of sample carbonates and meta-sediments. Within Croatia, down- was dissolved in aqua regia at 90 ºC in a microwave di- stream to Sisak, the Sava River flows mostly through Qua- gestion unit. The solution was diluted and analyzed by a ternary beds. Perkin Elmer SCIEX ELAN 6100 ICP-MS instrument, using the USGS GXR-1, GXR-2, GXR-4 and GXR-6 ref- The Ljubljanica River (a tributary of the Sava River in erence materials. This digestion is not total. However, the Slovenia) drains a semi-dried marsh pan of alluvial sedi- international standard methods for determining action lim- ments, lenses and delta-type clastic sediments like gravel, its are also based on an aqua regia leach [21] and justify, sand and clay [15]. The catchment of the Ljubljanica River therefore, the applied procedure. drains Mesozoic carbonates and Upper Paleozoic sedimen- tary rocks. Most of the water at its springs is derived from Two different statistical procedures (box plot and MAD the surrounding karst area. methods) were used to identify anomalous geochemical data. At first, dependent on the empirical cumulative distri- The geology of the Voglajna region was described in bution plots, normal or lognormal box plots were con- detail by Nosan [16], Hamrla [17], and Buser [18]. The structed, and box length was the interquartile range. Out- studied area represents a young tectonic basin, filled by liers were values between 1.5-3 box lengths from the upper Quaternary deposits. In the northern part of Voglajna re- or lower edge of the box. Far outliers (extremes) were val- gion, there are Pleistocene clays, quartz gravel and sand. ues more than 3 box lengths from the edge of the box [22, In the SE part, Miocene sand, sandstone, marly limestone 23].