engleski

Sediments from Savinja, Voglajna and Hudinja rivers (Slovenia), reflecting anomalies in an old metallurgic area

Stream sediments from Savinja and its tributaries, Voglajna and Hudinja rivers, which drain an old metallurgic area of Slovenia, have been studied by detailed mineralogical, chemical, Mössbauer and geostatistical methods. It is a case study, which provides an example for a possible chemical threat to aquatic ecosystems, such as toxic contamination with Zn, Cd, Cu, Ni, Pb, Ag, Hg and As, in the Celje area. Concentrations of 53 elements were determined in fractions <63 &#956; m by ICP-MS. Cluster analysis of Q-modality, applied on total geochemical data set, was used to disaggregate it into three subsets. The geochemistry of stream sediments belonging to the largest cluster has been used to identify the background geochemical signatures, related to geology of the drainage basin area. 57Fe Mössbauer spectroscopy at room temperature was used to study iron, which is a major element, partly present in poorly crystalline compounds (oxides and hydroxides). Spectra were fitted with two to four doublets. Hyperfine parameters were obtained and Fe(III)/Fe(II) ratio was calculated. The ratio is higher in Voglajna than in Savinja and Hudinja. Fe(III) is retained in silicates, or as finely dispersed iron oxide. Fe(II) is assumed to be retained in calcite, dolomite and chlorite. Regarding contamination of the studied region, some improvement was observed. Anthropogenic association due to iron metallurgy in the recent past, detected lately on attic dust, was not detected in recent sediments. Anthropogenic association Ti-Nb, reflecting titanium oxide production, is still observed in recent sediments. Highly correlable high concentrations of Zn, Ag and Cd show that these elements still reflect metallurgic activity in Celje region. In spite of elevated concentrations of toxic elements within the Celje region, only in two locations concentrations of several toxic elements are above the values, which can cause serious toxic effects with respect to recommended sediment quality criteria.

Stream sediments; Savinja; Voglajna; Hudinja; Mineral composition; Chemical composition; Anomalies' determination

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