An assessment of multielemental composition in stream sediments of Kupa River drainage basin, Croatia for evaluating sediment quality guidelines

Levels and sources of 8 major and 45 trace elements in stream sediments of a non-mountain drainage basin of Kupa River, which is of supra-regional interest, is presented for the first time. It is a significant water resource for Croatia, Slovenia, and Bosnia and Herzegovina, but in its great part under mines from the war (1991-1995), and therefore difficult to sample. Concentration of elements was determined in fine fraction (< 63 mu m) by ICP-MS. The drainage basin was delineated in such a way that each basin segment corresponded to the area upstream and upslope of each sampling site. Selected examples for Ca and Ba distributions are presented. Cluster analysis of Q-modality, applied on a geochemical data set, was used to disaggregate it into three more homogenous subsets. Cluster I was interpreted as a region with significant anthropogenic Ba anomaly. Cluster 2 represents a part of the Supradinaric belt with ophiolites. Sedimentary formation was under the influence of mafic and ultramafic lavas, but also neutral and acid volcanism. Cluster 3 represents a part of the Dinaric carbonate platform, on which shallow water carbonate sedimentation occurred. The geochemistry of stream sediments belonging to the largest cluster 3 has been used to identify background geochemical signatures, related to geology of the mining-free area. Assessment of sediment contamination with toxic elements was performed in comparison with existing criteria for sediment quality. Toxic effects are possible with respect to Ba, Mn, Ni, Pb, Zn, and P, on some locations. Two Ba anomalies were found. One is significant and of anthropogenic origin in the western part of the basin, whereas that in the eastern part of the basin is of natural origin. Concentrations of Ba can be followed far downstream in Kupa River. Therefore, Ba can be suggested as a suitable parameter to study sediment transport in. the studied region.