Elements in size-fractionated bottom sediments of the Elbe River in its Czech part

Abstract

The concentrations of 45 elements, and the content of organic substances, amorphous inorganic substances and minerals were determined in 26 samples of Elbe River bottom sediments to determine the correlation between the element composition and the grain size in the $ \le $ 4, 4—8, 8—16, 16—32, 32—63 μm and bulk samples $ \le $ 63 μm fractions. The purpose of this study was to obtain information about the role of particle size and their mineral composition as a control of element concentrations in sediments, the potential remobilization of elements under changing environmental conditions, and the chemical speciation of the large excess concentrations of elements in this system.¶About 22—56% of the estimated element yield was associated with sediments with a grain size of less than 4 μm and 82—97% of the element yield was found in the fraction smaller than 32 μm. Sequential extraction carried out for 20 potentially reactive elements in the $ \le $ 63 μm bulk samples and the $ \le $ 4 μm fraction showed the increased importance of exchangeable ions in the order Mn = Ni < Mg < Sr < Cu < Zn < Ca < K < Cd < Na < Mo, reducible fractions Zn < Sr < Mo < Co < Cu < Ni < Pb < Mn < Cr < Be < V = Fe < As < Ag, oxidizable chemical phases As = Ca < Cd < K < Sr < Fe = Mn < Zn = Mg < Mo < Co = Ag < Pb < Li < Cu = V < Ni < Cr = Na < Be with small concentrations from lithogenic phases Mn < As < Pb < Sr < Zn = Cu = Na < Be < V < Ni < Cr < Fe < K < Mg < Li. The major accumulative phases were identified for the individual elements.