Physical speciation of sediment associated heavy metals in active floodplains of the Danube and Tisza rivers, Hungary Several studies deal with the riparian zones as natural buffers. The present paper focus-es on the filtration and physical speciation of suspended load by riparian belts, which is a form of appearance of this buffer function. Five transects were traversed along the Danube and Tisza rivers. Samples were taken from riverbank deposits, natural levees, along the line of willow grove

more »

... and from the active floodplains. Grainsize composition of sediments and concentrations of five heavy metals (Cd, Co, Cu, Pb, Zn) were determined from the average samples. The samples were physically separated into five fractions (<5 mm, 5–10 mm, 10–20 mm, 20–50 mm, >50 mm). The heavy metal content of each fraction was determined. Our results have shown that the profile and exposition of bank have an effect on the fractionation of the sediment and heavy metals. The presence or absence of natural levees (and crevasses) cause different distribution of the heavy metals along the transects and manifest themselves in different granulometry of the individual samples. Alluvia of the two studied rivers have distinct sediment texture and heavy metal distribution. This is due to the different origin and properties of these sediments and heavy metals. Bevezetés Számos tanulmány, tankönyv és ismeretterjesztõ írás foglakozik a vízfolyásokat kísérõ hullámterek szûrõ és puffer funkcióival. Két legjelentõsebb folyónkat övezõ hullámterek szintén ket-tõs szûrõként funkcionálnak. A hullámterek kiülepítik a kiáradó folyóvízben lebegõ anyagot, a sza-lagként követõ erdõk pedig egyúttal hatékonyan csökkentik a levegõ szálló és ülepedõpor-tartalmát 1 A kutatás az OTKA T 38122 és T 38394 témaszámú tematikus pályázatok, valamint a Környezetvédelmi Célalap K-36-02-00105 számú projektjének támogatásával valósult meg. 2 MTA Földrajztudományi Kutatóintézet, 1112 Budapest, Budaörsi út 45.