【作者】 李春荣；

【导师】 王文科；

【作者基本信息】 长安大学 ， 地质工程， 2009， 博士

【摘要】 土壤石油污染对土壤功能、生态环境和人类健康等有严重的影响,对其污染机理、生态效应以及修复技术研究越来越受到人们的重视。生物修复技术由于具有处理成本低、处理条件温和、无二次污染等优点而受到广泛关注和快速发展。本论文针对陕北土壤石油污染的现状,通过室内实验和田间试验,揭示了石油污染物在黄土介质中的吸附、解吸、垂向迁移特征和自然降解规律；系统探索并揭示了石油污染土壤对微生物生长、植物—土壤生态系统微生物群落及典型植物生长影响的特征。从分离筛选高活性石油降解菌入手,在揭示了石油污染物微生物降解动力学特征和优化生态条件的基础上,建立了石油污染土壤植物修复及植物-外源微生物联合修复技术,提出了生物修复效果评价指标并对修复效果及安全性进行了初步评价。主要研究成果及结论如下：1、静态吸附与解吸实验揭示石油类污染物在于黄土—水两相之间的分配符合Freundlich方程,吸附动力学可以用对数方程描述,土壤中有机质含量是影响石油烃吸附的主要因素；黄土中石油类污染物的释放速度很快但释放量很小且释放量随pH值的增加而增大。通过土柱淋滤实验表明：石油类污染物在黄土中的垂向迁移速度很慢,污染物主要滞留在表层土。摇床培养和堆制实验揭示生物降解是石油污染物在黄土中自然去除的主要途径。2、通过对石油污染环境中的微生物生长以及植物生长特性的研究表明：细菌的对数生长曲线延滞期较真菌明显短缩且稳定期菌落数远高于真菌,是污染环境中微生物构成的主体；石油污染的植物-土壤生态系统中,嗜油菌数量显著提高且不同植物响应程度差异较大。土壤中石油初始浓度在300mg/kg～50 000mg/kg时,对苜蓿出苗抑制率可达到24%～78%；10 000mg/kg时,植物叶绿素含量、超氧化物歧化酶(SOD)活性显著降低,丙二醛(MDA)含量明显增加,植物生理性状受到显著影响；玉米、向日葵、大豆生物量依次减少14.5%、21.2%和7.6%,植物生长受到显著抑制；石油污染物在植物不同部位均有不同程度的残留,其中根部残留量最大,其次是籽仁或茎部。土壤中石油烃初始质量浓度为10 000mg/kg时,玉米、向日葵和大豆籽仁中石油烃残留量分别达到3.82 mg/kg、4.64 mg/kg、1.14 mg/kg,玉米籽粒中苯并[a]芘(BaP)含量超过国家食品规定的限量(<5μg/kg),达到5.78μg/kg,食品安全受到威胁。3、从石油污染介质中分离得到28种石油降解菌,其中微球菌属5株、节细菌属6株、不动细菌属3株、芽孢杆菌属2株、微杆菌属和假单胞菌属各1株；曲霉属2株、头孢霉属、毛霉属、酵母属和木霉属各1株。通过降解性能研究筛选出10株高效石油降解菌；单因素和多因素实验研究揭示了石油污染土壤微生物降解的优化生态条件为：营养物配比C：N：P=40：2：1,电子受体H2O2累计加入量(30%溶液)9 000 mg/kg,湿度50%；较适合的表面活性剂为十二烷基苯磺酸钠。影响生物降解因素的主次关系依次为：湿度,表面活性剂,营养物,电子受体。4、以玉米、向日葵、苜蓿、大豆为修复植物进行的连续两年原位修复试验表明：150 d可以使土壤中初始质量浓度为10 000 mg/kg的石油烃分别降解42.5%、46.4%、44.7%和40.6%；500 d降解95.5%、96.1%、92.4%和87.6%,修复效果明显；节细菌-DX-9为外源强化菌,与玉米、向日葵形成的联合原位修复体,150 d可以使石油烃分别降解72.8%和76.4%；500d降解率分别达到97.6%和98.9%；芽孢杆菌(DX-6)、假单孢菌(WX-2)、节杆菌(DX-10)和微杆菌(DX-1)组成的外源强化混合菌与苜蓿、大豆构建的联合原位修复体,150d石油烃降解达到63.5%和51.7%,较相应植物修复分别提高了27.3%和42.1%；500 d降解率分别达到98.8%和92.7%。石油污染土壤植物-外源微生物联合修复效果显著。5、经过连续两年的生物修复,供试植物的生长状况、籽仁品质、土壤中石油污染物的残余量、试验区土壤理化性质,生物群落分布,土壤呼吸强度均与对照无显著差异。石油烃对植物的生态毒性消除,污染土壤恢复健康状态。供试植物与外源微生物构建的生物修复技术对面源石油污染土壤的治理是安全的、有效的。更多还原

【Abstract】 Oil-contanminated soil could considerably influence the normal function of the soil, the ecological enviroment and the human health. People are paying more and more attention to the study of contamination mechanism, ecological effects and bioremediation technology of petroleum-contanminated soil. Biological treatment of petroleum-contanminated soil has many advantages, for example, low cost, mild conditions, no second pollution. So the method has caused wide public concern and developed rapidly. In view of the present situation of the petroleum-contanminated soil in Northern Shaanxi Province, the characteristics of absorption, desorpton, vertical migration and degradation of petroleum pollutants in loess medium have been revealed through the laboratory experiments and field tests. Effects of petroleum-contanminated soil on the growth of microorganism and the microbial community in ecological system of the soil-plant have been systematically investigated. Oil degrading microorganism is isoled firstly in this thesis, bioremediation technologies of phytoremediation and plant-introduced microbes of petroleum-contanminated soil are constructed on the basis of the research of the dynamics and the most suitable ecological conditions in biological degradaton of petroleun pollutants. The evaluaton system of the bioremediation of oil-contaminated soil is set up, the efficacy and safety of the bioremediation technology is evaluated preliminarily according to this standard after the field trial had been finished. The achievments of the research are as follows:1. The study of the adsorption and desorption of petroleum pollutants in batch tests have discovered that the distributes of petroleum hydrocarbon in loess phase-water phase conforms to the Freundlich equation, the adsorption dynamics may be described by the logarithm equation approximately, the organic matter content is major factor affecting the adsorption capacity. The desorption of petroleum pollutants in the loess can balance quickly,but the release quatity is very small,it increases along with the pH.The vertical transport characteristics of petroleum pollutants in the loess has been studied by column penetration tests. The results show that this process is very slow, and the most of the petroleum pollutants are intercepted in the surface soil. The result of shaking cultivation and stacked experimentation shows that biodegradation is a major removal way of petroleum pollutants in the loess naturally.2. The study of the characteristics of the growth of microorganism and plants in petroleum-contanminated enviroment shows that the lag phase of bacterium’s logarithmic growth curve has shortened remarkably than that of the fungi, the colony numbers of bacterium in stationary phase has been higher than the fungous numbers, the bacterium is the main body of the microflora in petroleum polluted enviroment. oil-philic microorganism are increasing in number greatly and there are remarkable increase difference for different plants in the petroleum-contanminated ecological system of the soil-plant. When the initial concentration of the petroleum in soil is 300 mg/kg～50000 mg/kg, the germination-percentage of the alfalfa is decreased 24%～78%. In treatment with petroleum concentration of 10000 mg/kg, chlorophyll contents and superoxide dismutase (SOD) activities are decreased remarkably,malondialdehyde (MDA) contents are increased obviously, the physiological characters of plants can be significantly affected by petroleum, the biomass of the corn, the sunflower and the soybean decrease 14.5%,21.2%,7.6% respectively, the plant’s growth can be inhibited. Residual petroleum hydrocarbon has been discovered in different parts of the plants, Petrolic residual quantity is the highest in the root, next in the seed or stem. When the petroleum density in the soil achieves 10000 mg/kg, petrolic residual quanlity of the corn,the sunflower, the soybea can reached 3.82 mg/kg,4.64 mg/kg and 1.14 mg/kg respectively in seed, benzo[a]pyrene(BaP) content in the corn is 5.78μg/kg, which is more than the government-required standard (<5μg/kg). The food stafety is threatened.3.28 predominant strains for degradating oil have been isolated from the petroleum-contaminated medium,and identified results show they are 5 Micrococcus sp.,6 Arthrobanter sp.,3 Acinetobacter sp.,2 Baccillus sp., a Microbacterium sp.,a Pseudomonas sp. and 2 Aspergillus sp., a Cephalosporium sp.,a Mucor sp.,a Saccharomyces sp., and a Trichoderma sp..10 strains of high-efficient petroleum hydrocarbon degradation bacteria have been obtained by the study of their degradation rate for petroleum hydrocarbon. The study of single-factor experiments and multifactoral experiments has indicated that the best ecological conditions of petroleum-contaminated soil biodegradation are that nutrition material C:N:P= 40:2:1, electron receiver body H2O2 (the liquid of 30%)joining quantity amount to 9000 mg/kg, water content is 50%, suitable surface-active agent is Sodium Dodecyl Benzene Sulfonate. the relation of primary and secondary factor of the bioremediation is water concent, surface-active agent, nutrition material, and electron receiver respectively.4. The study of the in-situ bioremediation experiments for two years time showed that the systems consisting of the corn, the sunflower, the alfalfa and the soybean had obvious repair function to the petroleum-contaminated soil, the petroleum biodegradation efficiency of 4 phytoremediation systems were 42.5%,46.4%,44.7% and 40.6% respectively with initial concentration of 10000 mg/kg within 150 days. The petroleum biodegradable efficiency were 95.5%,96.1%,92.4% and 87.6% respectively within 500 days. The union bioremediation systems of "corn-exogenous Arthrobacter-DX-9" and "sunflower-exogenous Arthrobacter---DX-9" had made the petroleum pollutants of initial concentration of 10000 mg/kg to reduce 72.8% and 76.4% within 150d, increasing by 71.3% and 64.6% compared with controlled field, which there was no exogenous Arthrobacter. The petrolic content in the soil of the experimented fields had been remved 97.6% and 98.9% within 500 days. The union bioremediation systems consisting of "alfalfa-the mixed strains", which make up of Bacillus, Pseudomonas, Arthrobacter and Microbacterium, and "soybeans-the mixed strains" had made the petroleum pollutants of initial concentration of 10000 mg/kg reduce 63.5% and 51.7% within 150d, increasing by 27.3% and 42.1% compared with controlled field.The petrolic content in the soil of the experimented fields had been removed 98.8% and 92.7% within 500 days. The union bioremediation has achieved satisfactory efficiency.5. The growth indexes, the quality characters for seeds, the residue of petroleum in different parts of the plants and the physic-chemical properties, microbial distribution and respiration intensity of the soils in experimented fields are not significant difference compared with controlled fields. Eco-toxicity of petroleum-contaminated soil to plant is eliminated. The contaminated soil has been restored to health by the bioremediation for two years time. The bioremediation technology established by the plants and exogenous bacteria is safe and effective for the treatment of the non-point source petroleum-contaminated soil.更多还原