The effect of heavy metals (Cd and Zn) on microbial respiration in calcareous and non-calcareous soils

摘要

Heavy metals are well known to be toxic to environment, particularly agricultural soils, when present in excessive concentrations. Microbial respiration is one of the soil properties that may be influenced by heavy metals. The aim of this study is to investigate the effect of 0, 150, and 300mg·kg<'-1> soil cadmium (Cd) and 0, 750, and 1500mg·kg<'-1> soil zinc (Zn) on microbial respiration as measured by CO<,2> release in calcareous and non-calcareous soils. Experimental results indicated that the rate of C-CO<,2> release was related to the physico-chemical characteristics of the soils. It is positively related to soil CaCO<,3> content. Respiration intensities of the soils (mg C-CO<,2>g<,-1> organic C) showed significant and negative correlations with metal contents. This observation was associated with the sharp decrease of the respiration rate when the metal contamination increased.