四种氮肥对海甘蓝(Crambe abyssinica)富集镉锌效应及根际土壤细菌群落特性的影响

以Cd和Zn复合污染土壤为研究对象,通过盆栽试验,研究了相同施氮量的4种氮肥(CO(NH_2)_2、(NH4)_2SO_4、NH_4Cl和NH_4NO_3)对海甘蓝累积Cd、Zn效应及根际土壤细菌群落变化的影响。结果表明,海甘蓝种子对地上部生物量的贡献最大。海甘蓝地上部生物量(b)表现为b(NH_4Cl)b((NH_4)_2SO_4)≈b(NH4NO3)≈b(CO(NH_2)_2),地上部干重占整株干重的96%~98%。与施用CO(NH_2)_2相比,施用NH4Cl和(NH4)_2SO_4显著降低了土壤pH值,促进了土壤Cd和Zn活化,提升了海甘蓝茎、根等部位的Cd和Zn质量比;而NH_4NO_3与CO(NH_2)_2处理间的海甘蓝各部位Cd、Zn质量比并无显著差异。4种氮肥强化处理的海甘蓝Cd和Zn总提取量并未存在显著差异,整株海甘蓝对Cd和Zn的提取量分别为168.12~234.87μg/株和9 090.08~17 429.37μg/株。海甘蓝富集的Cd和Zn主要集中在地上部。与施用CO(NH_2)_2相比,施用NH_4Cl显著降低了海甘蓝根际土壤细菌Chao1,而CO(NH_2)_2、(NH_4)_2SO_4和NH_4NO_3处理间的OTUs、Chao1和Shannon Index均无显著差异。土壤有效Cd和Zn质量比是影响海甘蓝根际细菌丰度变化的最主要环境因素。利用海甘蓝植物提取修复Cd-Zn污染土壤时,应综合权衡强化措施对生物量、土壤pH值、Cd和Zn迁移分布及根际细菌特性的影响,不断优化氮肥施用参数(类型、时间和施用量),以获取最佳提取修复效果。

Effect of the 4 nitrogen fertilizers on the rhizospheric soil bacterial communities and the uptake of Ca and Zn by Crambe abyssinica

The given paper intends to present the results of our pot experiment for testing the influence of the 4 nitrogen fertilizers (urea,ammonium sulfate,ammonium chloride,ammonium nitrate) on the growth and accumulation of Cd and Zn,the phytoextraction efficiency and the bacterial community composition in the mixed contaminated soil by crambe(short for Crambe abyssinica).The results of our simulated experiment and investigation show that the shoot biomass of crambe has been existing in the following consequential order:NH4Cl ＜ (NH4)2SO4 ≈ NH4NO3 ≈ CO(NH2)2.With the shoots representing 96％-98％ of its total biomass,its seed biomass is also composed most of the shoot biomass in all the treatments.Therefore,as compared with the treated results of CO(NH2)2,the application of NH4Cl can help to significantly reduce the soil's bacteria diversity of Chao1 and Shannon Index in the rhizosphere.Statistically speaking,in treating the nitrogen fertilizer,the total Cd and Zn extraction tends to amount to 168.12-234.87 μg per plant and 9 090.08-17 429.37 μg per plant,respectively,though the concentrations of Cd and Zn in its tissues (root,stem,leaf and seed) have not been affected.In spite of this,the investigation of the OTUs,Chao1 and Shannon Indexes demonstrates that no significant difference can be found on the soil's bacteria diversity in rhizosphere as the result of treating by using NH4NO3 and CO (NH2) 2.Rather,the soil's effective Cd and Zn contents serve as the main factors that may affect the community composition of rhizosphere soil's bacteria.Therefore,it is of great significance to pay attention to the study of the plant growth biomass and its potential risks (the toxicity of metals to the soil microorganisms) likely to be brought about when nitrogen fertilizer is used (the kinds of the nitrogen fertilizer,the application time,and the application rate),for it is necessary to evaluate the phytoextraction before the needed steps are to be taken to move on for its successful commercial application.