阿特拉津在沉水植物根际的降解及其微生物多样性特征

发布时间：2018-05-04 14:53

本文选题：阿特拉津 + 菹草　；参考：《华中农业大学》2017年硕士论文

【摘要】：阿特拉津是一种常用除草剂,其残留在环境中是一种持久性有毒有机污染物,由于其性质稳定、半衰期长,使得其在土壤环境残留量较高。土壤中的阿特拉津在淋溶、地表径流等作用下进入水环境中,会在沉积物的吸附作用下固定于沉积物中,近年来许多水环境的沉积物中频频检出阿特拉津。因此,有必要对沉积物中阿特拉津的修复进行研究。根际修复被认为是目前最具潜力的修复技术之一,其中有机污染物在沉水植物根际沉积物中的化学与生物化学行为是其在根际降解中的主要机制。以微生物多样性作为指标在监测沉积物变化和对环境胁迫的反映方面均很重要,其对进一步了解土壤/沉积物微生物群落状态也十分有用。故本文选取两种沉水植物菹草和穗花狐尾藻,研究阿特拉津在不同沉水植物根际的特异性降解行为及其沉积物微生物多样性特征。主要研究结果如下:(1)在南湖沉积物中添加2 mg/kg的阿特拉津,分别开展菹草和穗花狐尾藻对阿特拉津的降解实验。60 d实验结束时:菹草体系中,实验处理(根际)和对照处理(非根际)的沉积物中阿特拉津残留浓度分别为0.43 mg/kg、0.60 mg/kg,降解率分别为78.63%、70.01%,两处理之间存在显著性差异(p0.05);穗花狐尾藻体系中,实验处理(根际)和对照处理(非根际)的沉积物中阿特拉津残留浓度分别为0.13mg/kg、0.32mg/kg,降解率分别为93.69%、81.75%,两处理之间存在显著性差异(p0.05)。穗花狐尾藻对沉积物中阿特拉津的降解率高于菹草。两个体系的不同处理中得到的阿特拉津降解产物只有羟基阿特拉津,且随着时间的推移,羟基阿特拉津的含量也逐渐降低,实验处理(根际)中的羟基阿特拉津含量始终高于对照处理(非根际)。本研究的两个体系中,可溶性有机碳含量与阿特拉津的降解率没有显著相关关系,但根际中DOC含量相对较高,阿特拉津降解率也相对较高;可溶性硝态氮和可溶性铵态氮在实验期间呈下降趋势,实验处理中的含量高于对照处理。(2)两种沉水植物研究体系的不同处理中,脱氢酶活性均随培养时间而呈上升趋势。本研究的两个体系中,沉积物中细菌数量随时间呈上升趋势,其大小排序为:实验处理阿特拉津空白处理对照处理。植物的根际效应使微生物对污染物的适应加强或者是能够利用外源污染物作为碳源或氮源,从而间接地影响脱氢酶的活性,使之加强,促进了阿特拉津的降解。从沉积物中筛选出3株可以阿特拉津为唯一氮源生长的菌株,其对阿特拉津的降解率分别为:14.49%,60.02%,13.50%。(3)选取第60 d穗花狐尾藻体系中各处理组沉积物进行基因组DNA高通量测序。丰富度和多样性指数结果显示,各处理沉积物中微生物群落丰富度排序如下:实验处理阿特拉津空白处理空白处理对照处理,各处理的沉积物中微生物群落多样性排序如下:阿特拉津空白处理实验处理空白处理对照处理。群落结构分析表明,实验处理中有两种菌的丰度都与其他三个处理之间存在显著性差异:脱硫叶菌属、硝化螺菌属,它们可能是与阿特拉津降解相关的菌种。对照处理中也有两种菌的丰度与其他三个处理之间存在显著性差异:norank_c_OPB35_soil_group、norank_f_Xanthomonadales_Incertae_Sedis,说明沉积物中只添加阿特拉津的处理会促进上述两种菌的生长繁殖。
[Abstract]:Atrazine is a commonly used herbicide. Its residue is a persistent toxic organic pollutant in the environment. Because of its stable nature and long half-life, it has a high residue in the soil environment. Atrazine in the soil enters the water environment under the action of leaching and surface runoff, which will be fixed to deposit under the adsorption of sediment. Atrazine is frequently detected in many water environment sediments in recent years. Therefore, it is necessary to study the repair of atrazine in sediments. Rhizosphere repair is considered to be one of the most potential remediation technologies, and the chemical and biochemical behavior of organic pollutants in the rhizosphere sediments of submerged plants is its Rhizosphere in the rhizosphere. The main mechanism of degradation is important in monitoring sediment change and environmental stress. It is also very useful for further understanding of the state of soil / sediment microbial community. Therefore, two kinds of submerged plants of Potamogeton crispus and Honoka foxes are selected to study the different submerged plants of atrazine. The main results are as follows: (1) the addition of 2 mg/kg of atrazine in the sediments of the Nanhu Lake was carried out at the end of the experimental.60 D experiment on the degradation experiment of atrazine, Potamogeton crispus and Honoka, respectively: the experimental treatment (rhizosphere) and control treatment (non rhizosphere) in the Potamogeton crispus. The atrazine residues in the sediments were 0.43 mg/kg and 0.60 mg/kg, respectively, and the degradation rates were 78.63%, 70.01% and two respectively (P0.05). The atrazine residual concentration in the experimental (rhizosphere) and control (non rhizosphere) sediments of Honoka fox system was 0.13mg/kg, 0.32mg/kg, and degradation rate respectively. There was a significant difference between the 93.69%, 81.75%, and two treatments (P0.05). The degradation rate of atrazine in the sediments was higher than that of Potamogeton crispus. The atrazine degradation products obtained from the two systems were only hydroxy atrazine, and the content of hydroxy atrazine was gradually reduced as time went on, and the experimental treatment was carried out. The content of hydroxy atrazine in the rhizosphere was always higher than that of the control (non rhizosphere). In the two systems of this study, there was no significant correlation between the soluble organic carbon content and the degradation rate of atrazine, but the content of DOC in the rhizosphere was relatively high, and the atrazine degradation rate was also higher; the soluble nitrate nitrogen and the soluble ammonium nitrogen were in the experiment. The content of the experimental treatment was higher than that of the control treatment. (2) the activity of dehydrogenase increased with the culture time. The number of bacteria in the two systems of this study increased with time, and the size of the amount of dehydrogenase in the two systems of this study was: the experimental treatment of atrazine blank. The rhizosphere effect of the plant makes the microorganisms adaptable to the contaminants or can use the exogenous pollutants as carbon or nitrogen sources, thereby indirectly affecting the activity of dehydrogenase, strengthening it and promoting the degradation of atrazine. 3 strains of atrazine are screened from the sediments to grow as the only nitrogen source. The degradation rates of atrazine were as follows: 14.49%, 60.02%, 13.50%. (3) selected sixtieth D Honoka fox system, the sediments were sequenced by the genome DNA. The richness and diversity index showed that the richness of the microbial communities in the sediments were as follows: the experimental treatment of atrazine blank treatment blank treatment The diversity of microbial communities in all the treated sediments was treated as follows: atrazine blank treatment experiment treatment blank treatment control treatment. Community structure analysis showed that there were significant differences between the abundance of two kinds of bacteria in the experimental treatment and the other three treatments: desulphurizing leaf bacteria, nitrifying snails, they may be There was a significant difference between the abundances of two species of atrazine and the other three treatments in the control treatment: norank_c_OPB35_soil_group, norank_f_Xanthomonadales_Incertae_Sedis, indicating that the only addition of atrazine in the sediments could promote the growth and reproduction of the two species.

【学位授予单位】：华中农业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X592;X17

【参考文献】