单壁碳纳米管对紫花苜蓿根际土壤中PAHs降解及微生物群落的影响

Effects of single-walled carbon nanotubes on degradation of polycyclic aromatic hydrocarbons and microbial community in rhizosphere soil of Medicago sativa

为探究单壁碳纳米管(SWCNTs)对紫花苜蓿根际土壤中多环芳烃(PAHs)降解及微生物群落的影响,以高浓度PAHs污染土壤为供试土壤种植紫花苜蓿,并添加不同含量的SWCNTs,通过室内盆栽试验,分析了根际土壤中PAHs的降解效应及微生物群落响应。结果表明:添加0.5 g·kg^(-1)和5 g·kg^(-1)SWCNTs使土壤中PAHs的去除率分别显著降低了3.43%和6.98%(P<0.05),SWCNTs对PAHs降解的抑制作用主要来源于5环和6环高分子量PAHs。添加SWCNTs对紫花苜蓿生长并未产生毒害作用,当SWCNTs的添加量为5 g·kg^(-1)时,紫花苜蓿根长、地上部鲜质量和根鲜质量与对照(不添加SWCNTs)相比分别显著增加了21.44%、49.13%和100.00%(P<0.05)。qPCR和高通量测序结果表明,添加SWCNTs对土壤细菌生物量、丰富度和多样性无显著影响,但显著改变了土壤细菌群落组成。较高添加量的SWCNTs(5 g·kg^(-1))显著降低了污染土壤中PAHs潜在降解菌属Phenylobacterium、Reyranella、Brevundimonas和Pseudorhodoferax的相对丰度。研究表明,添加SWCNTs抑制了根际土壤中PAHs的去除,尤其是5环和6环PAHs,同时改变了土壤中微生物群落,并且抑制了与PAHs降解相关的微生物。

The study investigated the effect of single-walled carbon nanotubes(SWCNTs)on the degradation of polycyclic aromatic hydrocarbons(PAHs)and microbial communities in alfalfa rhizosphere soil.An indoor-pot experiment was performed to analyze the degradation of PAHs and the response of microbial communities by planting alfalfa(Medicago sativa)and adding different contents of SWCNTs to soil contaminated with high concentrations of PAHs.Addition of 0.5 g·kg^(-1)and 5 g·kg^(-1)SWCNTs significantly reduced the removal rate of PAHs in the soil by 3.43%and 6.98%(P<0.05),respectively.The inhibitory effect of SWCNTs on degradation of PAHs mainly involved high-molecular-weight PAHs with five to six rings.SWCNTs were not toxic to alfalfa.When the supplemented level of SWCNTs was 5 g·kg^(-1),root length,shoot weight,and root weight of alfalfa were significantly increased by 21.44%,49.13%and 100.00%(P<0.05),respectively,compared with those of the control.The results of qPCR and high-throughput sequencing revealed that the addition of SWCNTs had no significant effect on soil bacterial biomass,richness,and diversity;however,it significantly changed the composition of soil bacterial community.The higher level of SWCNTs(5 g·kg^(-1))significantly reduced the relative abundance of potential PAH-degrading bacteria in contaminated soil,including Phenylobacterium,Reyranella,Brevundimonas and Pseudorhodoferax.