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

Abstract

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 Příbram (P1, P2) in the Czech Republic]. The content of microbial biomass showed a tendency to decrease in Kremikovtzi soils whereas in Příbram 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 Příbram soils. Heavy metals decreased the content of microbial biomass in Kremikovtzi soils whereas the contaminated soil from Příbram 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 qCO2 in heavy metal contaminated Příbram soil. The respiratory activity in non-contaminated Příbram soil remained during the experiment lower in comparison to contaminated one, however the addition of zeolite increased qCO2.