ABSTRACT

The study of the breakdown of the fungicide carbendazim widely used in Poland was carried out under model conditions simulating the environment of river water moderately polluted, distilled water, and dynamic aqueous ecosystem. The experiments were conducted using the fungicide in concentrations about 1 and S mcg/1 a t two temperatures - about 20°C and S°C, and after adaptation of microorganisms to the presence of the fungicide. Taking the results of the experiment with river water the rate of the breakdown was studied, determining also the kinetic parameters of the breakown process: rate constants and half-times of breakdown. This process agreed, as a rule, with the kinetic equation of first order and depended on the type of water, initial concentration, temperature and microflora adaptation to the environment of the tested substance. The process of carbendazime breakdown after adaptation of the microorganisms of river water to the fungicide was occuring a t a much higher rate at both test temperature and depended on the initial concentration. Temperature decrease to about S°C inhibited the process of carbendazime degradation, but only if the initial concentraion was higher. The concentrations of carbendazime in aqueous environment under dynamic conditions during 14-day exposure decreased by 14-19% and had no negative influence on the biocenosis of the experimental ecosystem Carbendazime was not taken up by water-thyme and Lebistes reticulata in the experimental ecosystem, was poorly concentrated by snails and accumulated slightly in the sediments of the ecosystem.