Paddy Soil Microbial Diversity and Enzymatic Activity in Relation to Pollution

Chemical and microbial characterizations of a rice paddy soil subjected to long-term heavy metal pollution (P) and nonpolluted (NP) soil are used to investigate whether the distribution of heavy metals (Cd, Cu, Pb, and Zn) regulates microbial community activity, abundance, and diversity at the microenvironment scale. The soils are physically fractionated into coarse-sand, fine-sand, silt, and clay fractions. Long-term heavy metal pollution notably decreases soil basal respiration (a measurement of the total activity of the soil microbial community) and microbial biomass carbon across the fractions, respectively. The coarse-sand fraction is more affected by pollution than the clay fraction and displayed a significantly lower respiration and dehydrogenase activity. The abundances and diversities of bacteria were less affected under pollution. Long-term heavy metal pollution decreased the microbial biomass, activity, and diversity in long-term exposure.