Development of a monitoring network on Lake Balaton, Hungary

A monitoring system has been developed to characterize the bottom sediments of Lake Balaton. Samples were collected inside of the lake, from the top layers to 60 cm in depth. The samples were dried at room temperature and then sieved through 2-mm and 63-mum sieves. The total concentration of elements was measured by atomic absorption spectrometry (AAS) with an RSD of <5% from solutions. The determination of the mineralogical phase composition of sediments was carried out by X-ray powder diffraction (XRD). The main constituents of samples were quartz, calcite, mica, dolomite, chlorite, feldspar, smectite, kaolinite, pyrite and some amorphous materials. Ten elements were investigated, and Ni, Cr and Zn were chosen to be discussed in details. Results were compared with Hungarian soils, geochemical background values, sediment quality values (SQVs) and sediment background values (SBVs). Records showed that the average concentration of elements was usually less than that of SQVs and other background values for soils. However, some high concentrations at different sampling sites and depths surpassed the geochemical background values. Based on the results, it can be confirmed that the quality of the sediment inside Lake Balaton is satisfactory. (C) 2004 Elsevier B.V. All rights reserved.