中文关键词大气CO₂升高Pb耦合效应细菌真菌群落特征 英文关键词elevated atmospheric CO₂Pbcombined effectsbacteriafungicommunity characteristics

作者	单位	E-mail
贾夏	长安大学水利与环境学院, 旱区地下水文与生态效应教育部重点实验室, 西安 710054 长安大学土地工程学院, 陕西省土地工程重点实验室, 西安 710054	jiaxianavy@163.com
Lkhagvajargal Khadkhurel	长安大学水利与环境学院, 旱区地下水文与生态效应教育部重点实验室, 西安 710054
赵永华	长安大学土地工程学院, 陕西省土地工程重点实验室, 西安 710054
张春燕	长安大学水利与环境学院, 旱区地下水文与生态效应教育部重点实验室, 西安 710054
张宁静	长安大学水利与环境学院, 旱区地下水文与生态效应教育部重点实验室, 西安 710054
高云峰	长安大学土地工程学院, 陕西省土地工程重点实验室, 西安 710054
王子威	长安大学土地工程学院, 陕西省土地工程重点实验室, 西安 710054

中文摘要 阐明CO₂升高和土壤重金属污染耦合对植物根际微生物群落的影响对明确大气CO₂升高背景下土壤重金属污染的植物根际生态效应意义明显.利用开顶箱系统模拟了连续4个生长季大气CO₂浓度升高［（700±27）μmol·L^-1］与土壤Pb污染（15.6 mg·kg^-1和515.6 mg·kg^-1）耦合对刺槐幼苗根际土壤微生物群落的影响.结果表明，与Pb污染相比，高浓度CO₂提高了（P<0.05）Pb污染下幼苗根际土壤总N含量，同时也提高了根际土壤pH、总C和水溶性C含量及C/N，降低了（P<0.05）根际土壤总Pb和可溶性Pb含量.细菌丰富度和多样性在耦合条件下较Pb污染增加（P<0.05），而真菌丰富度降低（P<0.05）和多样性增加（P<0.05）；细菌和真菌群落中相对丰度最高的前两位优势属变化不显著，但其它类群如Anaerolineaceae、Solirubrobacterales、Eurotiomycetes、Aspergillus和Trichocomaceae的相对丰度受大气CO₂浓度升高与土壤Pb污染耦合影响显著；相对丰度较高的前10位细菌和真菌优势属与根际土壤环境因子的冗余分析表明，根际土壤总C和可溶性Pb是显著（P<0.05）影响细菌优势属环境因子，总C对真菌优势属影响显著（P<0.05）.结果表明刺槐幼苗根际土壤总C和可溶性Pb是根际土壤细菌群落变化的显著影响因子，而真菌群落仅受总C的显著影响. 英文摘要 Elevated atmospheric CO₂ could affect the speciation of heavy metals in rhizosphere soils by changing root exudates, thereby influencing soil microecosystem in the rhizosphere. Therefore, understanding the function of heavy metals in soils on rhizospheric ecology under elevated atmospheric CO₂ scenarios is highly important. Here, we investigated the combined effects of a four-year period of elevated air CO₂ concentrations[(700±27) μmol·L^-1] and Pb-contamination (15.6 mg·kg^-1 and 515.6 mg·kg^-1) on the soil rhizopheric microbial community of Robinia pseudoacacia L. seedlings. Significant (P<0.05) effects of CO₂, Pb, and their interaction on bacterial richness and fungal diversity were observed. Relative to Pb exposure alone, elevated CO₂ significantly increased pH, total C, total N, and water-soluble organic carbon, and the C/N ratio under Pb exposure (P<0.05) and significantly decreased total and soluble Pb content (P<0.05). The richness and diversity of bacteria increased (P<0.05), fungal richness decreased (P<0.05), and microbial diversity increased (P<0.05) under the combined treatments relative to Pb contamination alone. The changes in the relative abundance of the top two dominant bacterial and fungal genera were not significant; however, differences in the relative abundances of other groups, such as Anaerolineaceae, Solirubrobacterales, Eurotiomycetes, Aspergillus, and Trichocomaceae, were significant between the different treatments. According to a redundancy analysis, total C and soluble Pb had a significant influence (P<0.05) on the dominant bacterial genera, and total C affected (P<0.05) the dominant genera in the fungal community. These results suggest that the responses of soil environmental factors to the combination of elevated atmospheric CO₂ and Pb could shape soil microbial community structure in the rhizosphere of R. pseudoacacia seedlings.

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