重金属污染土壤植被恢复过程中的土壤微生物特征

Soil-microbial properties in the re-vegetation process of the barren land contaminated with heavy metals

研究了重金属污染裸地植被恢复4、5、6a和7a后的植物凋落物积累量、土壤化学特征、重金属含量与土壤微生物特征。结果表明：与未恢复裸地相比，植被恢复显著地提高了根际土壤中的有机碳（18．6—31．1g·kg^-1）、总氮（0．88—1．56g·kg^-1）和总磷（0．34—0．39g·kg^-1）含量（P〈0．05）；上述指标以及植物凋落物积累量没有随植被恢复年龄增加而提高。植被恢复地土壤pH、重金属铅、锌、铜的总量和DTPA（diethylenetriaminepentaacetic acid）可提取量均显著地高于未恢复裸地（P〈0．05），并且随植被恢复年龄增加呈现出一致提高的趋势。土壤微生物量碳和氮在5个研究样地中的变化趋势基本一致，即最大值均出现在样地RV（恢复5a）（127．34mg·gdw^-1和2．45mg·gdw^-1），然后在样地RVI（恢复6a）和RVII（恢复7a）均有不同程度地下降。微生物量氮在4个恢复样地中变化显著（P〈0．05）。土壤微生物基础呼吸和功能多样性最大值发生在样地RVI（59．10mg·gdw^-1和3．14），随后在样地RVII中略有下降（P〉0．05）。未恢复裸地的土壤微生物对羧酸和胺类化合物利用率显著大于4个恢复样地（P〈0．05），对碳水化合物、氨基酸、聚合物和杂合物的利用率显著低于4个恢复样地（P〈0．05）。主成分分析结果表明，未恢复裸地的CLPP（community level physiological profiles）指纹与恢复样地存在显著差异（P〈0．05），4个恢复样的CLPP指纹相似。

Litter accumulation, soil-chemical parameters, heavy metal contents and soil-microbial properties after the revegetation 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.