MACROPHYTES AS INDICATORS OF BIOAVAILABLE CD, PB AND ZN FLOW IN THE RIVER PRZEMSZA, KATOWICE REGION

A 5 km stretch of the river Przemsza, in southern Poland, was investig ated with the aim of finding out if a gradient of metal pollution was present along the river and to determine the bioavailable flow of Cd, Pb and Zn between water, sediment and submerged macrophytes. In situ e xperiments in pots as well as experiments in sealed jars were performe d by using Potamogeton pectinatus and Myriophyllum verticillatum. Thes e were planted in polluted sediment from 3 localities along the river and in unpolluted sediment in order to find out if metals were taken u p by the shoots or roots. After 6 weeks exposure, plants, sediment and water were analysed for their metal contents. The unpolluted sediment accumulated heavy metals, indicating addition of metals from the wate r, while the polluted sediment instead released metals to the water. T he plants accumulated heavy metals, but the absence of differences in metal content in plants grown in unpolluted and polluted sediment indi cated that the metals were accumulated mainly by the leaves from the w ater. Increasing concentrations of Pb in plants indicated an increasin g down-stream gradient of Pb. There were also higher concentrations of Cd and Zn in shoots of both plant species downstreams compared with u pstreams. (C) 1996 Elsevier Science Ltd