Geochemical properties of stream sediments and suspended particulate matter and determination of geochemical background values for the Alpine River Mura.

Suspended particulate matter (SPM) and stream sediments (STS) from 66 locations (main channel and tributaries) were geochemically investigated in the Alpine transboundary river Mura to provide an integrated view of the long-term accumulation of pollutants and the present-day pollution status of the catchment, including the distribution of YREE (yttrium and rare earth elements) which are regarded as emerging pollutants due to use of modern technologies. Cluster analysis identified 4 geochemical associations in SPM for the low water regime: (1) Cu, Cd, Bi, Pb, Mn, Ni and Cr; (2) Ca, Sr; (3) U, Fe, Co, Rb, YREE, V, Ti, Mg and (4) Ba, Ga, Al and Li. Six groups were identified for STS samples: (1) YREE, U, Mn, Fe, Ti; (2) As, V, Ga, Al; (3) Ca, Sr, Na; (4) Cu, Ni, Co, Cr, Mg; (5) Ag, Bi, Pb, Cd, Zr and (6) Ba, Zn, Rb and Li. The study concluded that the identified geochemical groups reflect the geological composition of the catchment area as well as anthropogenic impacts, notably mining, steel industry, and urbanisation. The spatial distribution of YREE was identified as an indicator of sediment provenance. Eu and Ce anomalies were observed in SPM, reflecting the local geology, while the Gd anomaly may indicate anthropogenic inputs. The study concludes that STS primarily reflect the geogenic distribution of elements, while SPM is a more sensitive indicators of anthropogenic activities for the Alpine fluvial environment. Study also provides upper background and threshold values for Mura River catchment that may serve as reference values in future environmental studies.