苯系物污染含水层水位波动带内的物-化-生过程研究

发布时间：2018-10-08 08:00

【摘要】：伴随着近年来石化工业的飞速发展,环境中石油化工类污染问题也日趋严重化,尤其是地下水土环境因其污染具有潜伏性、隐蔽性,一旦发现问题通常已造成难以挽回的严重后果。苯系物具有密度小且不易溶于水的特点,因此其在地下环境中主要浮于地下水面发生迁移。而在地下水面附近,常因开采或回灌、河道水位涨落、降雨等因素促使地下水位反复下降与回升,形成地下水位频繁变动区,被称为地下水位波动区。该区域内苯系物的迁移转化,由于地下水位波动作用以及随之产生的氧化-还原特征变化而具有特殊性,因此,本文依托国家自然科学基金项目《地下水位波动带内BTEX在天然和空气扰动修复下的分异演变机理》,采用室内一维砂柱模拟实验,通过监测水位变动过程中污染物以及各种物理、化学、生物特征指标的变化,开展对苯系物在地下水位波动带内衰减规律研究,并探讨其中地下水环境中的物-化-生变化规律,该研究成果有助于更加清楚污染物在地下环境中的迁移转化过程,从而为研究污染物的去除提供科学理论基础。通过本次室内实验和所获数据的系统分析,获得以下研究成果:1、水位波动过程中随水流迁移的甲苯浓度衰减速率符合一阶衰减模型,不同介质条件下的衰减速率不同,中砂和含10%黏土细砂中甲苯衰减速率分别为6.4 mg·L~(-1)·d~(-1),5.3 mg·L~(-1)·d~(-1);而非波动条件下中砂和含10%黏土细砂中甲苯衰减速率仅为0.57 mg·L~(-1)·d~(-1),0.59 mg·L~(-1)·d~(-1);水位波动明显加大了甲苯随水流迁移的速率,水位波动条件下的甲苯残留量小于非波动条件。2、随累积出水量的增加,不同条件均发生了以NO_3-Fe~(3+)SO_4~(2-)CO_2为顺序的还原反应。波动条件下氧化还原电子受体转换的时间晚于非波动条件,中砂介质氧化还原电子受体转换的时间晚于含黏土介质。3、微生物种类在不同条件下随时间发生了不同程度的变化,在不同时间的介质中也发生了明显的变化。波动条件下的微生物种类数量变化程度大于非波动条件,含黏土细砂介质中微生物种类数量变化程度大于中砂介质。Shannon指数、Simpson指数、Pielou指数在不同条件下随时间呈现明显不同的变化趋势。4、水位波动和非波动过程中,甲苯衰减前期主要以物理作用为主,后期以化学-生物作用为主;微生物种群与环境因素在数量上分析得出,有机物含量与OTU值之间有明显正相关性;介质的粒径与OTU值呈正相关性,介质比表面积与OTU值呈负相关性;Pseudmonas菌种在中砂波动条件下与TOC、NO_3-、SO_4~(2-)之间相关性强,受到他们的综合影响,含黏土细砂-波动条件下,Acinetobacter与HCO_3~-、NO_2-、Fe~(3+)相关性强,受综合影响程度高;其他不同菌种与环境中物理-化学因素都呈现了不同的相关性。
[Abstract]:With the rapid development of petrochemical industry in recent years, the problem of petrochemical pollution in the environment is becoming more and more serious, especially the underground soil and water environment is latent and hidden because of its pollution. Once a problem is discovered, it usually has serious consequences that are irreparable. Benzene series have the characteristics of low density and insoluble in water, so they mainly migrate in underground environment. However, in the vicinity of groundwater surface, factors such as mining or recharge, fluctuation of river water level, rainfall and other factors promote the groundwater table to fall and rise repeatedly, forming the area of frequent change of groundwater level, which is called the fluctuation area of groundwater level. The migration and transformation of benzene series in this area are special because of the fluctuation of groundwater level and the resulting redox characteristics. In this paper, based on the National Natural Science Foundation project "the differentiation and evolution mechanism of BTEX in the groundwater level fluctuation zone under natural and air disturbance remediation", the indoor one-dimensional sand column simulation experiment is used to monitor the pollutants and various physics in the process of water level change. The change of chemical and biological characteristic indexes, the study on the attenuation law of benzene series in the fluctuation zone of groundwater level, and the discussion on the law of matter-meta-generation change in groundwater environment, The results of this study are helpful to better understand the transport and transformation process of pollutants in underground environment and thus provide a scientific theoretical basis for the study of pollutant removal. Through this laboratory experiment and systematic analysis of the obtained data, the following research results: 1: 1, the attenuation rate of toluene concentration migrating with water flow during water level fluctuation accords with the first order attenuation model, and the attenuation rate is different under different media conditions. The attenuation rate of toluene in medium sand and fine sand containing 10% clay was 6.4 mg L ~ (-1) d ~ (-1) and 5.3 mg L ~ (-1) d ~ (-1) respectively, while that in medium sand and fine sand containing 10% clay was only 0.57 mg L ~ (-1) d ~ (-1) 0.59 mg L ~ (-1) d ~ (-1). The residual amount of toluene under water level fluctuation is smaller than that of non-fluctuating condition. With the increase of cumulative water output, NO_3-Fe~ (3) SO_4~ (2-) CO_2 is the order of reduction reaction in different conditions. The transition time of redox electron receptor was later than that of non-fluctuating condition under fluctuating condition, and the time of redox electron receptor conversion in medium sand was later than that of clay medium. The species of microorganism changed in different degree with time under different conditions. Obvious changes have also taken place in the medium at different times. The variation of the number of microbial species under fluctuating conditions is greater than that under non-fluctuating conditions. The variation degree of microbial species in clay fine sand medium is greater than that in medium sand medium. Shannon exponent Simpson index and Pielou index show obvious different trend with time, water level fluctuation and non-fluctuation process. The main factors of toluene decay were physical action in the early stage and chemical-biological action in the latter stage, the quantitative analysis of microbial population and environmental factors showed that there was a significant positive correlation between organic matter content and OTU value. The particle size of the medium was positively correlated with the OTU value, and the specific surface area of the medium was negatively correlated with the OTU value. Under the condition of medium sand fluctuation, Pseudmonas strain had a strong correlation with TOC,NO_3-,SO_4~ (2-), which was influenced by their comprehensive influence. The correlation between Acinetobacter and HCO_3~-,NO_2-,Fe~ (3) was strong under the condition of fine sand and fluctuating clay, and the influence degree was high, and the physical and chemical factors of other bacteria species and environment were different.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X131.2

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