【作者】 王威；

【导师】 林学钰；

【作者基本信息】 吉林大学 ， 地下水科学与工程， 2012， 博士

【摘要】 伴随世界工业的腾飞，各国对石油的需求量不断加大，在石油勘探、开采、运输、加工的过程中，淋落、泄漏等环境污染事故时有发生，对生态环境造成巨大危害，短期内难以恢复。石油类污染物进入土壤环境，并通过渗漏进入含水层，严重危及地下水环境安全。东北地区石油资源丰富，是我国主要的石油产区，同时又是我国重要的老工业基地、商品粮基地，一旦发生地下水石油类污染，危害极大。从以往的研究来看，对复合污染物迁移转化研究主要集中在多环芳烃类（芘、萘、菲），以及苯系物（BTEX）的复合污染等，组分之间从分子结构、化学性质、作用机制方面均具有一定的相似性。而芳香烃和氯代烷烃复合污染则由于其组分种类、理化性质、作用机制差别大，所开展的研究较少，对于此类的复合污染的作用机制和在地下水中的迁移转化机理尚不明确，尤其在这种复合污染条件下有机质对芳香烃和氯代烷烃污染物的吸附行为，以及生物降解机理进行研究具有重要的意义。本次论文选取东北某石油类污染场地作为研究区，污染场地面积约800m2，原为低洼的苇地，由于输油管道常年埋藏于地下，管道锈蚀并发生泄漏，整个泄漏过程缓慢、持续时间较长，对地下水造成了污染。通过勘察发现，含水层浅部1-2m岩性为不连续砂质粉土，向下以粉砂为主体含有细砂夹层。研究区地下水主要的补给来源为大气降水入渗和侧向径流补给，主要排泄项有侧向流出量和蒸发排泄，地下水位埋深浅，水力梯度约为3-5‰。在综合分析已有资料和研究成果的基础上，通过水文地质调查、地下水土样品采集和测试查明污染场地地下水中石油类特征污染物的时空分布特点，并通过室内静态实验、渗流柱模拟实验研究揭示特征污染物在地下水、土中的迁移转化机理，建立特征污染物在地下水中溶质运移模型，预报污染物浓度的变化。吸附作用是石油类污染物自然衰减的主要作用之一，影响污染物在含水层中的流动性和滞留性，以及生物降解等其他转化过程。本论文通过静态实验研究了多组分复合污染条件下，包气带、含水层介质对特征污染物的吸附规律、竞争吸附规律，以及含水层介质成分（矿物和有机质）对特征污染物吸附的贡献率和作用规律等。采用包气带、含水层介质粉土、粉砂、细砂开展吸附动力学实验和吸附热力学实验，从吸附动力学结果来看，粉土对三种特征污染物的吸附平衡时间最短，约6h基本达到平衡；粉砂对特征污染物的吸附平衡时间约为16h，在16h后基本达到平衡；细砂对特征污染物的吸附平衡时间约为24h。场地介质对特征污染物的吸附以线性模型为主，本次主要采用Henry模型对介质吸附能力进行分析。三种有机污染物在颗粒越细的介质中，越易被吸附。污染物迁移性的顺序为二氯甲烷>三氯甲烷>苯，既二氯甲烷更易随水流迁移，而苯则更易被吸附。污染物竞争吸附实验显示当苯与氯代烃共存于地下水中时，随着苯在溶液中浓度的增加，促进了含水层介质对氯代烃的吸附。氯代烃对苯的吸附影响则表现为，当苯浓度较高时，氯代烃对苯在含水层介质上的吸附具有抑制作用。有机质在含水层介质吸附污染物过程中起到了重要作用，通过模拟粉砂对比实验发现有机质占含水层介质总质量约1%，对于污染物的吸附的贡献率却达到10%-40%。生物降解作用是特征污染物在迁移转化过程中主要的自然衰减作用之一，本次研究从场地微生物代谢能力、场地微生物多样性、降解动力学、生物降解影响因素等几个方面开展相关研究工作，揭示包气带、含水层介质中微生物对特征污染物的降解规律。场地土壤基础呼吸强度主要表现为呼吸强度随深度增加逐渐减弱，在到达地下水面（约1.1m）后又有升高趋势。包气带整体的呼吸作用强度要高于含水层，包气带0.2-0.5m基础呼吸作用强度最高，总体上ZK3孔的基础呼吸强度大于ZK1、ZK6孔。包气带、含水层中硝酸盐、氨氮、亚硝酸盐等的含量对微生物活动强度有一定影响。包气带、含水层水土条件下降解动力学实验发现三种污染物均符合一级衰减动力学模型。包气带水、土环境下特征污染物的降解速率要高于含水层。通过降解菌影响因素试验发现，场地地下水的PH、矿化度、Cl-条件更适宜特征污染物降解菌的生长，过高或过低反而会起到抑制作用。地下水中硝酸盐浓度低于51.79mg/L时，随着硝酸盐浓度升高降解菌数量和污染物降解率升高。地下水中磷酸盐浓度升高能够促进二氯甲烷、三氯甲烷降解菌的生长，但浓度过高时，对苯降解菌起到抑制作用。为了更好的查明污染场地包气带、含水层微的生物多样性。本次研究采用PCR-DGGE手段对土壤样品微生物多样进行分析后，采用ward法（离差平方和法）对样品进行聚类分析，建立场地微生物群落的系统树。从聚类分析结果来看场地包气带、含水层介质中的微生物群落主要分为两大族群，族群A以包气带微生物群落为主，在场地中主要分布深度在0-1.0m；族群B以含水层微生物群落为主体，主要分布深度在1.0-1.8m。DNA测序结果显示污染场地包气带、含水层中的微生物，除具有土壤根瘤菌以及假单细菌外，还有与其他石油渗漏场地、油田区域相同的甲烷降解菌和耐石油污染细菌，说明污染场地包气带、含水层介质中的微生物在石油类污染物的长期作用下，部分已经能够耐受石油类污染物，并对其有降解作用。虽然DGGE图谱经识别条带较多，但是能够进行切胶送测的样品数量有限，并未发现氯代烃、苯降解菌，说明二者并非污染场地中的显著微生物群落，数量有限。本次研究开展了特征污染物在场地不同污染途径下迁移转化规律的渗流柱模拟实验研究。含水层渗流柱模拟实验主要用于模拟污染径一中特征污染物的迁移过程，实验结果显示，吸附对污染物衰减的贡献率为：三氯甲烷87%，二氯甲烷85%，苯94%；生物降解的贡献率为：三氯甲烷3%，二氯甲烷2%，苯3%。说明研究区含水层介质粒径细，对污染物吸附容量大；地下水径流滞缓，使污染物同含水层介质的接触时间增长。在自然条件下，微生物量小，降解菌含量更少，导致生物降解作用所占比重偏低。从包气带积水淋滤实验结果来看特征污染物在包气带中的迁移顺序为，二氯甲烷>三氯甲烷>苯，且石油污水在穿透包气带时，浓度仍较高，会对地下水造成危害。从特征污染物迁移预测结果来看，三氯甲烷对污染场地造成的危害最小，在100d之后就低于EPA饮用水标准，苯和二氯甲烷的危害要高于三氯甲烷，分别在500d和1000d以后低于EPA饮用水限值，但二氯甲烷彻底清除需要时间较长，建议采取必要的治理措施。更多还原

【Abstract】 With the world’s industrial take-off, the oil demand is constantly increasing. Inthe process of oil exploration, mining and transportation, pollution accidents of spilled,and leaks often occur, and cause great harm to ecological environment, difficult torestore in a short-term. Petroleum contaminants enter the soil environment, andleakage into the aquifer，serious threat the safety of groundwater environmental.The northeast of China is China’s major oil producing areas, is rich in oil. Thesame time, it’s China’s old industrial base, and rice cultivation base, in the oilpollution event of groundwater, it will take great harm. From the previous studies, theresearch of composite pollutants migration and transformation is focused onpolycyclic aromatic hydrocarbons and combined pollution of BTEX. Molecularstructure, chemical properties, mechanism action of these components has a certainsimilarity. The migration and transformation of aromatics and chlorohydrocarboncomposite pollutants is not clear, especially the research of aromatic hydrocarbonsand chlorohydrocarbon pollutants adsorption on the organic matter and themechanism of biological degradation have great significance.This paper selected an oil pollution sites in the northeast of China as the studyarea, which is about800m2and originally was low-lying reed land. Because of all theoil pipelines are buried underground throughout the year, corrosion and leakage leadgroundwater polluted in the slow leakage process, continuous over a long period oftime. The investigation results show that the lithology of shallow aquifers1-2m wasdiscontinuous sandy silt, and the main body of aquifer is silt with fine sand interlayer.The main groundwater recharge sources of the study area are precipitation infiltrationand lateral runoff recharge, main discharge items are the lateral flow out andevapotranspiration. The groundwater level is shallow, hydraulic gradient is about3-5‰. In the basis comprehensive analysis of the existing data and research results,through the hydrogeological survey, the soil and groundwater sampling and testing, to find out the space distribution characteristics of the petroleum pollutants in thegroundwater,and through the indoor static experiments,as well as the seepagecolumn simulation experiments, to reveales the pollutants migration andtransformation mechanism in the groundwater and soil. Builds the solute transportmodel of the characteristics pollutants in the groundwater, and forecasts the changesof the pollutants concentration.Adsorption is one of the main functions of petroleum pollutants naturalattenuation, which affects the flow and retention of the pollutants in the aquifers andother transformation processes, such as the biological degradations. This paperthrough the static tests studied the adsorption mechanism and the pollutantscompetition adsorption mechanism in the medium of vadose zone and aquifer, and thecontribution of the composition of aquifer medium (mineral and organic matter)to theadsorption.Use the medium of the vadose zone and the aquifer, such as sandy silt, silt, finesand to carry out the dynamics adsorption experiments and the thermodynamicsadsorption experiments. The dynamics adsorption results show that the adsorptionbalance time of sandy silt is the shortest, the adsorption balance time is about6h; theadsorption balance time of silt is about16h; the adsorption balance time of fine sandis about24h. The features of three pollutants adsorption on the media of the sites canbe describe as linear model, this time we use Henry model to analysis the mediumadsorption ability. These three kinds of organic pollutants is easy to be adsorption inthe smaller particles of the media. The order of the pollutants mobility fordichloromethane> trichloromethane>benzene, the dichloromethane is easier to movewith groundwater, and the benzene is easier to be adsorption.The experiment of pollutants competitive adsorption shows that when benzeneand chlorinated hydrocarbons coexist in groundwater, with the concentration ofbenzene in solution increasing, adsorption of chlorinated hydrocarbons in the aquifermedia has increased. The impact of chlorinated hydrocarbons to the adsorption ofbenzene is expressed as when the benzene concentration is higher, chlorinatedhydrocarbons inhibit the adsorption of benzene in the aquifer media.Organic matters play an important role in adsorption of pollutants in the aquifer media. By comparative experiments of the simulating silt, organic matters account forapproximately1%of the total mass of the aquifer media and the contribution rate tothe adsorption of pollutants has reached10%-40%.Biodegradation is one of the main characteristics of pollutants in the migrationand transformation process of natural attenuation. In this research, the study hascarried out from the site intensity of microbial activity, the site degrading bacteriadiversity, degradation kinetics, impact factors of biodegradation etc. And thedegradation law of the biodegradation on the characteristic pollutants in the aquifermedia and the vadose zone has been revealed.The respiration intensity of the site soil mainly expresses as gradually weakeningwith the depth increasing, and gradually increasing near the water table(approximately1.1m). The overall respiration rate of vadose zone is higher than theaquifer. The intensity of basal respiration in the range of0.2-0.5m of vadose zone isthe highest. In general, the intensity of basal respiration of the well ZK3is higher thanthe well ZK1and ZK6. The concentration of nitrate, ammonia, nitrite in the aquiferand the vadose zone has a certain influence on microbial activity. Under the water-soilconditions of vadose zone and aquifer, the degradation kinetics experiment shows thatthe three pollutants mentioned above fit the first-order decay kinetics model. Thedegradation rate of pollutants in the vadose zone is higher than in the aquifer. By thedegrading bacteria factor experiment, the result shows that the site groundwatercondition of PH, TDS, Cl-are more suitable for the growth of the characteristicpollutants degrading bacteria, too high or too low will cause inhibitory. When thenitrate concentration is lower than51.79mg/L, the number of degradation bacteria andpollutant degradation rate will increase with the nitrate concentration increasing. Theincrease of elevated phosphate concentration can promote the growth ofdichloromethane and trichloromethane degradation bacteria. But excessiveconcentration can inhibit the growth of the benzene degrading bacteria.This research takes the means of PCR-DGGE for analyzing the microbialdiversity of the soil samples of vadose zone and aquifer, then use Ward method tocluster analysis the samples, establishes the system tree of the microbialcommunity.From the cluster analysis results to see the microbial community in the unsaturated zone and the aquifer medium, it can be mainly divided into two groups,group A takes the microbial community of unsaturated zone as the main body，themain depth of distribution is0-1.0m; while group B takes the microbial communityof the aquifer medium as the main body, the main depth of distribution is1.0-1.8meter.The DNA sequencing results show that the microorganism in the unsaturatedzone and the aquifer medium， not only have the soil rhizobium andPseudomonadaceae,but also have the methane degradation bacterium and oilpollution resistant bacteria which are the same as other oil leakage field or oil fieldarea, this indicates that under the long-term effects of petroleum pollutants, a part ofmicroorganism in the unsaturated zone and the aquifer medium have been able totolerate petroleum contaminants, and have the degradation function. Although theDGGE picture has more recognition band, only a limited number of the samples canbe cut and send to test，doesn’t find the chlorinated hydrocarbons and the benzenedegradation bacterium, which shows that both of them are not the notable microbialcommunity in the pollution sites, the number is in limited.This research carried out the seepage column simulation experiments about themigration transformation law of the characteristic pollutants in the sites underdifferent pollution ways. Aquifer seepage column simulation experiments are mainused to simulate the characteristic pollutants transport process in the first pollutionway. The experiment results show that the contribution of adsorption to pollutantsattenuation is trichloromethane87%, dichloromethane85%, benzene94%; thecontribution of the biodegradable, trichloromethane is3%, dichloromethane is2%,benzene is3%. This shows that the medium of the aquifer is much thinner, thepollutants adsorption capacity is more, besides, the groundwater flow is slow, thecontact time of the pollutants and the medium of the aquifer is longer. In the naturalconditions, the microbial biomass is small, the quantity of the degrading bacteria isless, which lead that the proportion of the biological degradation function is lower.From the result of the water leaching experiments in the vadose zone, we can see, themigration order of the characteristic pollutants is, dichloromethane>trichloromethane> benzene, and when the oil wastewater penetrate the vadose zone, the high concentration wastewater, will causes harm to groundwater.We use the indoor simulation experiment parameters to forecast theconcentrations of pollutants change. The forecast results show that thedichloromethane is least harmful to groundwater，below the EPA drinking waterstandards after the100d. The hazard of benzene and dichloromethane is higher thantrichloromethane, and below the EPA drinking water standard in the500d and1000d.But to completely remove the dichloromethane need for a long time, more than5000d， so recommended to take the necessary reconstruction measure, such as theAS-BS and so on.更多还原