Behaviour of some trace elements in alluvial sediments, Zagreb water-well field area, Croatia

Trace elements concentrations were determined in alluvial sediment area threatened by construction and operation of the pharmaceutical/chemical plant. Results gained by instrumental neutron activation analysis (INAA), electrothermal atomic absorption spectrophotometry (ETAAS), cold vapour AAS (CVAAS), optical emission spectrography (OES) show great differences in element distribution between two solid phases at the pollution source; high concentrations of Cr, Cu, Pb, Hg, Ni and Zn in creek sediments and indication of pollution in the upper soil layer at the Sava river banks downstream at the creek mouth. Concentrations and enrichment factors of elements determined in upper, bottom and water-bearing layers between creek and water-field area are of natural values. Some enrichment found for Sr, Ba and Ag could be explained with high calcite-dolomite content. For the time being, soil upper layers act as chemical filter preventing vertical infiltration. At the same time, Gorjak (Smrdljivka) creek sediments, rich in organic matter, cause clogging and prevent intensive pollution of groundwater. Thus the quality of water exploited from the water-well field is not endangered so far.