Publisher © Czech Geological Survey, ISSN: 2336-5757 (online), 0514-8057 (print)
Extent of the Jihlava River sediments load by geogenic elements
Published online: 24 October 2018 Foley, S. F. - Venturelli, G. - Green, D. H. - Toscani, L. (1987): The ultrapotassic rocks: characteristics, classification, and constraints for petrographic models. - Earth-Sci. Rev. 24, 81-134. Holub, F. V. (1997): Ultrapotassic plutonics rocks of the durbachitu series in the Bohemian Massif: Petrology, geochemistry and petrogenetic interpretation. - Sbor. geol. Věd, ložisk. Geol. Mineral. 31, 5-26. Kotková, J. - Schltegger, U. - Leichmann, J. (2010): Two types of ultrapotassic plutonic rocks in the Bohemian Massif: coeval intrusions at different crustal levels. - Lithos 115, 163-176. Müller, G. (1969): Index of geo-accumulation in sediments of the Rhine River. - Geol. J. 2 (3), 108-118. Müller, G. (1979): Heavy metals in the sediment of the Rhine - Changes Seity. - Umsch. Wiss. Tech. 79, 778-783. Sulovský, P. (2000): Srovnání chemismu třebíčského durbachitu a jiných durbachitů. - Geol. Výzk. Mor. Slez. v Roce 1999, 135-140. Škoda, R. - Novák, M. (2007): Y, REE, Nb, Ta, Ti-oxide (AB2O6) minerals from REL-REE euxenite-subtype pegmatites of the Třebíč Pluton, Czech Republic: substitutions and fractionation trendes. Lithos 95, 43-57. Wedepohl, K. H. (1995): The composition of the continental crust. - Geochim. Cosmochim. Acta 59, 7, 1217-1232.Abstract
The aim of the study was to determine the extent of the Jihlava River sediments load by geogenic elements and to evaluate the possibility to trace the weathering products from the Třebíč durbachite. The Třebíč pluton is typical of high potassium and magnesium contents (more than 3 wt.%), and also high contents of Cr, Ni, Rb, Cs, Ba, Th and U. Seven samples of stream sediments were collected from the Jihlava River. The heavy metal contents of As, Cr, Ni, Cu, Zn, Pb, and also selected elements such as U, Ta, Nb, Rb, Sr in all samples were determined using the ICP MS method. In order to evaluate the relation to the adjacent types of basement rocks, the results were compared to the published data (Kotková et al. 2010) of the local characteristic rocks. The contents of elements (As, Cu, Zn and Pb) evaluated in terms of potential contamination are low in the Jihlava River sediments and according to Igeo coefficient, they reach a maximum of 3. Higher contents were found for Cr and Ni, and no decrease in the flow direction was found (Table 1). It was considered whether the increased contents of Cr and Ni are due to anthropogenic load or related to the local geology and bedrock. Stream sediments were therefore assessed from the viewpoint of the intensity of weathering using the CIA (Chemical Index of Alteration) and WIP (Weathering Index of Parker) (Fig. 1) indices, and the specific ratios (Fig. 2) such as Nb/Ta (Fig. 2) U/Th, K/Rb and Sr/Rb. The previously mentioned ratios used to characterize the Třebíč pluton were found to be stable throughout the river flow and are not significantly changed by the Oslava River tributary. Considering that the Cr and Ni ratios are stable throughout the river flow and correspond to the ratios of these elements in the Třebíč massif, it can be stated that the increased contents of Cr and Ni are due to the weathering of source rocks (durbachites), and do not indicate anthropogenic contamination.References
