Publication details
Pilotné posúdenie riečnych sedimentov toku Jihlavy z pohľadu výskytu prvkových anomálií
| Title in English | Pilot assessment of Jihlava river sediments from the point of element anomalies |
|---|---|
| Authors | |
| Year of publication | 2018 |
| Type | Conference abstract |
| MU Faculty or unit | |
| Citation | |
| Description | The aim of the study is to determine elemental composition of soils overlying the Třebič pluton and river sediments from the middle flow of Jihlava and to review their potential relatedness. Composition of solid particles in the river flow reflects changing composition of surrounding geological units and also includes anthropogenic inputs. River Jihlava flows through the rocks of the Třebíč pluton. Třebíč pluton is the biggest durbachite complex in Czech republic. It is characterized by its high radioactivity, which is caused by the presence of durbachites which contain minerals rich in uranium and thorium (Zachovalová et al., 1999). Rocks of the durbachite series belong to ultrapotassic rocks, which are ranging in composition from amphibolite-biotic melasyenites to melagranites. Rocks contains higher concentrations of K, Rb, Cs, Th, U, Cr (Holub, 1997). Altogether 11 samples of soils in overburden of Třebíč pluton and 6 samples of river sediments of rivers Jihlava and Oslava in between Velké Meziřičí and Ivaň were taken. The samples taken were homogenized and the element content was determined by X-ray fluorescence analysis and concentrations of U, Th, K and Cs were measured by gammaspectrometry. In the river sediments of Jihlava were found low concentrations of Pb (9-55 ppm), Zn (55-266 ppm), As (3-24 ppm), Cu (15-55 ppm). The highest concentrations were reached by Cr (198-595 ppm) and Ni (58-267 ppm). In soil samples from overburden of Třebíč pluton were determined low concentrations of Ni (10-68 ppm), Pb (49-89 ppm), Cu (6-45 ppm), As (12-48 ppm). Higher concentrations were reached by Zn (45-154 ppm), Cr (28-158 ppm) and Rb (110-368 ppm). River sediments were assessed in terms of intensity of weathering with CIA and WIP indexes. Indexes did not significantly change in the direction of river flow. Furthermore, the representation of specific elements such as Nb/Ta was evaluated, and it corresponds to the characteristic ratio found in durbachite plutons. Source rock to the bottom sediments od Jihlava river are durbachites, localized in the upper part of the river flow. A link between type of contamination and bedrock was established. Considering that the ratios Cr and Ni are constant throughout the flow and they correspond to the rations of these elements in the Třebíč pluton, we can say, that higher concentrations of Cr and Ni are from weathering of source rocks, durbachites, and they do not indicate anthropogenic contamination. |