Fractionation of elements in sediment samples collected in rivers and harbors at Lake Balaton and its catchment area

A monitoring system has been developed to characterize the water quality of Lake Balaton. Sediment samples were collected in rivers and harbors around the lake and its catchment area. A modified four-step sequential leaching procedure was applied for determination of the distribution of elements. The fractions were: (1) exchangeable/bound to carbonate; (2) bound to Fe/Mn oxide; (3) bound to organic matter/sulfides; and (4) acid-soluble residue. Samples were taken in three seasons and the average concentration of the elements was calculated. Concentrations of elements were mostly well below the Hungarian standards set for soils and geochemical background values. Most of the elements were found in the acid-soluble residue and bound to organic matter/sulfide fractions, characterizing stable compounds in sediments. There was a difference on the elemental composition of sediments collected at rivers in the catchment area and harbors with relatively small boat traffic. Depending upon the nature of element and local pollution sources the concentration of Pb and Cu ions was found higher in sediments taken at harbors than that of small rivers. Generally, it can be stated that elemental concentration of sediments inside of the lake is smaller than at the catchment area, so the pollution from emission sources has not reached the lake yet. (C) 2000 Elsevier Science B.V. All rights reserved.