The character of the fine fractions of the bottom sediments of the Bohemian part of the Labe (Elbe) river

Abstract

The amounts of fractions with size _--<63 oem in the bottom sediments of the Bohemian part of the Labe (Elbe) river is variable. The grain-size distribution is poorly to very poorly sorted with a mean particle size from 5.1 to 12.2 oem.The crystalline phase of recent sediments of the Labe river draining various types of parent rocks has a simple mineral composition, with predominant mica/illite, quartz, kaolinite and chlorite (!-vermiculite _smectite). There are. also very small amounts of interstratification of 10 A and 14 A sheet silicates (11-13.6 A). Small amounts of Na-rich plagioclase, K-feldspar and calcite have also been found; accessory amounts of amphibole, authigenic gypsum and pyrite are also present. Opal in diatomic tests is an omnipresent constituent. In the amorphic inorganic phase, hydrated oxides predominate, where Si >A1 >Fe >Mn in a ratio of 64: 28: 22: 1. The greatest amount of amorphous inorganic and organic phases were found in the <4 oem fraction.A considerable part of the detrital material originates from soils formed on various igneous, metamorphic and sedimentary rocks, transported to the Labe by other rivers or directly by erosion in the immediate vicinity of the Labe river.

Trace elements levels in sediments of the Czech part of the Elbe river

“…Moore and Ramamoorthy (1984) suggested that all the Pb and Cd could be adsorbed or precipitated in the river sediments at pH > 7 (pH _> 6 for Cd and pH _> 7 for Pb). This corresponds to our findings, as the Pb, Mn and Cd contents were elevated in areas where the bottom sediments had the highest amounts of calcite and the pH of the water equalled 7.8 (Borovec and Mr~iz 1992;). Significant amounts of Mn and Pb were found in the oxidic component, which Karlsson et al (1988) stated to be indicative of coprecipitation rather than adsorption.…”