Effects of zeolite amendment on microbial biomass and respiratory activity in heavy metal contaminated soils

A laboratory incubation experiment with zeolite and glucose was performed to evaluate the effects of zeolite amendment in heavy metal contaminated soils from two smelter areas on some microbial characteristics (Kremikovtzi (K1, K2) in Bulgaria and Pribram (P1, P2) in the Czech Republic]. The content of microbial biomass showed a tendency to decrease in Kremikovizi soils whereas in Pfibram soils no significant effects were found after zeolite amendment. Respiratory activity and metabolic quotient (qCO(2)) decreased on the second and third day in Kremikovtzi soils amended with zeolite, no effects were observed in Pfibram soils. Heavy metals decreased the content of microbial biomass in Kremikovtzi soils whereas the contaminated soil from Pfibram area had the highest microbial biomass compared to non-contaminated soil during incubation. probably due to lower mineralization of carbon. The respiratory activity did not show any significant effects of zeolites on the evolution of CO2, and qCO(2), in heavy metal contaminated Pribram soil. The respiratory activity in non-contaminated Pfibram soil remained during the experiment lower in comparison to contaminated one, however the addition of zeolite increased qCO(2).