游离态四环素类抗生素抗性基因在土壤中的吸附特性

发布时间：2018-11-18 21:05

【摘要】：新兴污染物的污染风险是当前环境领域的热点问题之一,抗生素抗性基因的污染及其生态、健康安全问题更是关注的焦点,论文针对越来越受到人们重视的地下水抗生素抗性基因的来源和传播,结合北京再生水入渗现场四环素类抗生素抗性基因的分布特征,研究了游离态四环素类抗生素抗性基因在土壤中的吸附规律,主要取得了以下研究成果。以北京市潮白河再生水入渗场地作为典型研究区域,分析其地表水和土壤中tetB、tetM、tetO和tetW 4种四环素类ARGs的存在水平。结果表明,在地表水中tetB基因的检出率为83.3%,其余3种基因的检出率均为100%,四环素类ARGs的丰度大致符合沿程递减规律;在土壤中,4种基因的检出率均是100%,绝对量丰度高且变化幅度大,入渗场地内的底泥和包气带土样中4种基因的绝对量丰度均高于对照土。游离态四环素类ARGs质粒载体在研究区域的底泥和包气带介质中的吸附动力学符合双室一级动力学模型,吸附过程包含快速吸附和慢吸附两个过程。其吸附平衡符合Langmuir模型,拟合结果表明,底泥对其吸附量显著高于包气带介质,不同目的基因片段的导入对其在土壤中的吸附影响较小。使用qPCR方法,测定目标基因在吸附平衡前后的绝对拷贝数,以表征四环素类ARGs在土壤中的吸附特性。吸附达到平衡后,相比于加入量,四环素类ARGs的绝对量丰度降低1-2个数量级,吸附效果明显。四环素类ARGs在高拷贝数的初始量下,其吸附特性符合线性吸附。研究游离态四环素类ARGs在土柱模拟系统中的入渗迁移过程,“底泥-包气带”土柱I和“包气带”土柱II的表观渗透速率分别降低至0.046 m/d和0.17 m/d,达到稳定状态,对应的弥散度分别为3.2 cm和9.3 cm。高丰度配水回灌期内,相同时间点土柱II的出水基因丰度比土柱I的高一个数量级。游离态四环素类ARGs在底泥层和包气带层的滞留因子Rd分别为86.4和40.3。
[Abstract]:The pollution risk of emerging pollutants is one of the hot issues in the field of environment. The pollution of antibiotic resistance gene and its ecology, health and safety are the focus of attention. In this paper, the distribution of tetracycline antibiotic resistance genes in Beijing reclaimed water was studied. The adsorption of free tetracycline antibiotic resistant genes in soil was studied. Taking the infiltration site of reclaimed water from Chaobai River in Beijing as a typical research area, the levels of four tetracycline ARGs species, tetB,tetM,tetO and tetW, in surface water and soil were analyzed. The results showed that the detection rate of tetB gene in surface water was 83.3%, and the detection rate of the other three genes was 100. The abundance of tetracycline ARGs was approximately in accordance with the law of decreasing along the course. In soil, the detection rate of four genes was 100. The absolute abundance of the four genes was higher than that of the control soil, and the absolute abundance of the four genes was higher than that of the control soil, and the absolute abundance of the four genes in the soil samples in the infiltration site and in the soil samples of the aeration zone was higher than that in the control soil. The adsorption kinetics of the free tetracycline ARGs plasmid vector in the sediment and aeration zone media of the study area is in accordance with the two-chamber first-order kinetic model. The adsorption process consists of two processes: fast adsorption and slow adsorption. The adsorption equilibrium was in accordance with the Langmuir model. The fitting results showed that the adsorption capacity of the sediment was significantly higher than that of the aerated medium, and the effect of the introduction of different target gene fragments on its adsorption in soil was small. QPCR method was used to determine the absolute copy number of the target gene before and after adsorption equilibrium to characterize the adsorption characteristics of tetracycline ARGs in soil. After the adsorption reached equilibrium, the absolute abundance of tetracycline ARGs decreased by 1-2 orders of magnitude compared with the addition of tetracycline, and the adsorption effect was obvious. The adsorption characteristics of tetracycline ARGs at the initial amount of high copy number are in line with linear adsorption. The infiltration and migration process of free tetracycline (ARGs) in soil column simulation system was studied. The apparent permeation rates of soil column I and II were reduced to 0.046 m/ d and 0.17 m/ d, respectively. The dispersion is 3. 2 cm and 9. 3 cm., respectively. At the same time, the effluent gene abundance of soil column II was one order of magnitude higher than that of soil column I. The retention factor Rd of free tetracycline ARGs in sediment and aeration zone is 86.4 and 40.3, respectively.
【学位授予单位】：清华大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：X703

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