DECOMPOSITION OF WETLAND MACROPHYTES AFFECTS THE RELEASE OF HEAVY METALS FROM SEDIMENTS TO THE OVERLYING WATER.

The study aimed to examine the effect of the decomposition of macrophyte materials on the release potential of heavy metals (Zn, Cu, Pb and Cd) from the lake sediment to the overlying water. A laboratory experiment was carried out with a common macrophyte species (Carex cinerascens Kukenth) to examine the effects of macrophyte decomposition on the release of heavy metals (Cu, Zn, Cd, Pb) from the sediment. Fresh aboveground parts of the macrophyte were added to the sediment and the treated sediment was subsequently subjected to a permanent flood condition. Dissolved organic carbon (DOC), pH and heavy metal concentrations of the overlying water were measured during the 135-day experiment. In most cases, the rate at which heavy metals were released form the sediments was reduced after the addition of macrophyte biomass. The greater the amount of the macrophyte amendment, the greater the decrease in heavy metals released from the sediment. There is no significant correlation between the DOC concentration in the overlying water and the four heavy metals released from sediments. The addition of macrophyte biomass can reduce the heavy metals release from sediments. [ABSTRACT FROM AUTHOR]