Soil-microbial properties in the re-vegetation process of the barren land contaminated with heavy metals
重金属污染土壤植被恢复过程中的土壤微生物特征

Litter accumulation, soil-chemical parameters, heavy metal contents and soil-microbial properties after the re-vegetation of the barren land contaminated with heavy metals were investigated. The results showed that, the re-vegetation could significantly increase soil organic carbon (18.6-31.1 g·kg-1), total nitrogen (0.88-1.56 g·kg-1) and total phosphorus (0.34-0.39 g·kg-1) in rhizosphere soils compared with the barren land. However, the litter accumulation and the above indicators did not consistently increase with the re-vegetation ages. Soil pH, the total amount of Pb, Zn and Cu and DTPA-extractable Pb, Zn and Cu in the re-vegetated soils were significantly (P < 0.05) higher than those in the barren land, and linearly increased with the re-vegetation age. The RV site had the highest levels in both soil-microbial biomass carbon and nitrogen (127.34 mg·gdw-1 and 2.45 mg·gdw-1). There was a significantly (P < 0.05) different decline in microbial biomass nitrogen in the RVI and RVII sites. The RVI site had the highest levels in soil basal respiration and functional diversity (59.10 mg·gdw-1 and 3.14) and there was a decline in the RVII site. Both the basal respiration and functional diversity had no significant difference among the four re-vegetated sites. Soil-microbial community in the barren land had a greater utilization in carboxylic acids and amines/amides, and lower utilization in carbohydrates, amino acid, polymers and miscellaneous than those in the four re-vegetated sites (P < 0.05). The PCA (principal components analysis) showed that CLPP (community level physiological profiles) in the barren land was significantly (P < 0.05) distinct from the re-vegetated sites, but had no significant difference among the four re-vegetated sites.