Microbial biomass and activity dynamics in restored lands in a metal contaminated region

Soil microbial communities are important for biogeochemical processes, along with the cycling of nutrients in an ecosystem. Their enzymatic activities are key indicators of their responses to stress. The objective of this research was to assess the effect of land reclamation on microbial biomass and activities in soils impacted by metal contamination. Phospholipid fatty acid analysis (PLFA) (PLFA) results revealed a significant increase in total microbial biomass, fungi, actinomycetes, and bacteria when limed soils were compared to unlimed samples. This change in microbial biomass was associated with a significant increase of pH. The overall level of the β-glucosidase (BG), cellobiohydrolase (CBH), and aryl sulfatase (AS) activities was significantly higher in the dolomitic limestone treated soils than in the untreated samples. However, the activity of glycine aminopeptidase (GAP) was significantly lower in the limed soil than in unlimed samples used as reference. No significant differences (P ≥ 0.05) were observed between the two types of lands (limed vs unlimed) for other enzymes tested, which includes β-N-acetylglucosaminidase (NAGase), acid phosphatase (AP), alkaline phosphatase (ALP), leucine aminopeptidase (LAP), and peroxidase (PER). The levels of enzymatic responses also varied among sites. Overall, this study revealed for the first time the effects of liming on soil microbial activities in recently reclaimed sites damaged by metals.