【作者】 付向明；

【导师】 李绪谦；

【作者基本信息】 吉林大学 ， 环境工程， 2007， 硕士

【摘要】 多环芳烃是一种惰性较强的碳氢化合物,能广泛的存在于环境、水和土壤中。近年来的大量研究调查表明,空气、土壤、水体及生物体等都受到了多环芳烃的污染。生物毒性实验表明多环芳烃难以降解、在环境中有一定残留水平,具有生物累积性和“致癌、致畸、致突变”的三致性,对生态环境和人体健康构成了潜在威胁。污水灌溉作为一项节水措施,在我国的经济发展中起了不可替代的作用,沈阳市张士污灌区已经有五十多年的历史,由于长期采用污水作为农业灌溉用水,已经导致了地表土壤和水体的大面积污染,自然环境污染日趋严重。其中地表水和土壤的多环芳烃污染问题尤为突出,对本地区社会的可持续发展和生态与与生存条件产生了影响。局部地区情况已经极为严重,直接威胁到当地的农业生产和农民的生存环境。土壤包气带是一个多介质的环境,它是生物生长的基础,也环境污染物的主要归宿之一,进入环境中的多环芳烃污染物大部分残留在土壤环境介质中。多环芳烃在环境中的行为在很大程度上取决于多环芳烃在土壤中的迁移和转化行为。土壤对多环芳烃的吸附和降解不仅降低了多环芳烃的活性、移动性和挥发性,而且对于多环芳烃在大气和地下水中的残留性也有一定的影响。其中土壤中的有机质和土壤微生物是影响污染物在影响污染物在土壤中迁移与转化的最重要因素。本文用菲作为目标污染物,采用静态试验和室内土柱动态模拟研究相结合的方法,研究了菲在土壤中的静态吸附行为,吸附动力学行为和解吸行为。静态试验试图定量分析菲在土壤中的吸附和解吸行为,确认其吸附和解吸的曲线,通过多环芳烃菲在供试土壤中的吸附行为,科学分析影响多环芳烃吸附解吸行为的因素。通过室内土柱动态模拟试验研究了多环芳烃在包气带中的运移、吸附和微生物降解作用,探讨了多环芳烃在土壤包气带中的主要迁移转化方式。在室内土柱模拟试验中,将研究区包气带土壤按顺序装入采用直径9cm的有机玻璃柱,模拟在自然状态下两种不同流态下多环芳烃污染进入土壤包气带的过程。通过讨论菲在包气带中吸附、扩散和微生物降解等作用,研究了菲在包气带中的迁移转化规律和污染地下水的可能。研究结论如下:土壤有机质含量是控制包气带各层土壤吸附多环芳烃污染物能力的主要因素。菲在低浓度范围的吸附等温线成线型,在高浓度范围内呈一定程度的非线型。土壤的颗粒粒径对多环芳烃在包气带中的吸附和解吸也有影响。菲在各层土壤中的吸附可以用Freundlich方程进行拟合。菲在土壤各层中的吸附符合Lagergren二级吸附速率方程。静态吸附动力学试验结果表明,菲在土壤各层中的吸附和解吸过程均存在快速吸附阶段,快速吸附阶段能在8h内达到吸附平衡,解吸过程在2h内达到平衡。解吸过程释放出来的菲的量并不明显,大部分残留在土壤中,可以认为解吸并不是吸附的可逆过程,土壤的物理吸附可以被解吸。采用室内动态土柱试验对菲在土壤包气带中的迁移转化规律进行研究,研究结果表明:菲在包气带中的迁移是弥散、吸附、降解等多种作用共同作用的结果,包气带对菲的吸附过程是线型行为,可以用Linear吸附等温线S=KdC+S0表示,在连续给水方式和间断给水方式下,分配系数分别为0.134 L/g和0.201L/g;连续进水方式下,土壤吸附动力学可用Lagergren二级吸附速率方程表示,求出包气带土壤吸附饱和时的吸附量为476.19μg/g。包气带对菲的降解曲线基本符合一级动力学方程。在弥散试验中,测得弥散系数0.00498m2/d。并得在不同给水方式下的水化学迁移率,计算出菲经包气带垂直入渗进入地下水的时间分别为38.4a和58.7a。动态土柱试验结论与研究区现有状况相符,可以预测菲在包气带中的时空分布趋势,对加强水资源管理,防止地下水污染具有重要意义。更多还原

【Abstract】 PAHs is a strong inert hydrocarbons, widely exist in the atmosphere, water and soil. In recent years a large number of studies show that the air,soil, water and the organisms have been polluted by PAHs. Biological experiments of toxicity indicate that PAHs is hard to degradation, which has a certain residual in the environ ment. and PAHs have Bioaccumula~ tion and "carcinogenic, teratogenic, mutagenic", which posed a potential threat to the human health and ecological environment.Wastewater irrigation as a measure of saving water resource plays a indispensable part in our economic development. The history of Zhangshi wastewater irrigation region in Shenyang city traces back to more than fifty years ago. As long as the agricultural use of sewage water for irrigation has led to area pollution of the surface soil and water. Natural environmental pollution is getting worse. The soil, surface water and groundwater pollution survey in Zhangshi wastewater irrigation region found that PAHs pollution is very serious. PAHs pollutions of surface water and soil is particularly conspicuous on the region’s social and ecological sustainable development. Local area has been very serious, which directly threat to the local agricultural production and farmers living environment.Soil vadose zone is a multiphase environment, and it’s not only the basis of all organisms, but also one of the sink to the environmental pollutants. The majority of PAHs in environment residue in the soil. PAHs in the environment largely depends on the behavior of polycyclic aromatic hydrocarbons in soil migration and conversion behavior. The soil adsorption and degradation not only reduced the activity and volatile mobile of PAHs, but in the air and groundwater residues of PAHs is also a certain influence. The soil organic matter and the microbial are the most important factors affect the impact of PAHS pollutants in the soil relocation and transformation.In this paper, using the phenanthrene as a target pollutants, taking static experiment and indoor column dynamic simulation experiment method, research the static adsorption, the adsorption and desorption dynamics behavior of the phenanthrene in soil. Static experiment analyze the phenanthrene soil adsorption and desorption behavior quantitatively and its adsorption and desorption curves was confirmed. Through research the adsorption behavior of phenanthrene in soil, scientific analysis of PAHs affect adsorption and desorption behavior, determine the impact factors of PAHs adsorption and desorption behavior. Through Soil column dynamic simulation of PAHs in the soil vadose Zone migration, adsorption and microbial degradation, discuss the main movement to transform of PAHs in the soil vadose zone. In the indoor soil column experiment, The vadose zone soil is loaded in diameter 9cm plexiglass column according the sequence of the level in soil, simulating the process of PAHs pollution into the soil vadose zone in a natural state under two different flow patterns. Through discussions of the adsorption, the proliferation and microbial degradation in the Vadose Zone, study the migration and transformation rule of PAHs, and the possibility of groundwater pollution. Conclusion of the study are as follows:Soil organic matter content of the vadose zone is the main factors which control soil layers’adsorption capacity of PAHs. Phenanthrene adsorption isotherm is linear in the low concentration range, and is within a degree of non-linear in high concentrations. Soil particle size in the vadose zone influence the adsorption and desorption of PAHs. The adsorption of phenanthrene in the soil layers can be fitted Linear equation and Freundlich equation. The adsorption kinetics of phenanthrene in soil can be fitted Lagergren two level adsorption rate equation.Static adsorption kinetics results showed that the majority process of adsorption and desorption of phenanthrene are rapid stage, rapid adsorption stage in 8h reached equilibrium, the desorption process to achieve balance within 2h. the amount of phenanthrene released in Desorption process is small, and the majority of residue is in the soil. The adsorption and desorption process is not reversible process, the physical adsorption can be desorption.We researched the migration and transformation of phenanthrene in vadose zone by the indoor column dynamic simulation experiment. Longitudinal dispersion coefficient(D),adsorption coefficient (Kd) and retardation factor were abtained through curve fitting and parameter estimation. The results indicate that the migration and transformation of phenanthrene in vadose zone were due to dispersion, adsorption and biodegradation. The adsorption is reperesented by Linear Law, which adsorption coefficient (Kd) was 0.134 L/g和0.201 L/g differently in continuous water supply way and intermittent water supply way. Adsorption kinetics of continuous water supply colume can be used Lagergren two level adsorption rate equation, the adsorption capacity in vadose zone is 476.19μg/g when phenanthrene adsorption of soil reach adsorption balance. Longitudinal dispersion coefficient(D) is 0.00498m2/d in the experiment. Then calculate chemistry mobility in different water supply ways. In the end, draw a conclusion that the time which phenanthrene penetrate the vadose zone vertically into groundwater is 38.4a and 58.7a. the results of dynamic soil column experiments match successfully with study area conditions.更多还原