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乙醇混合汽油作为一种新型清洁能源正在许多国家推广使用。但当其泄露进入地下水体后，作为添加剂的乙醇将使燃油中有毒的BTEX滞后降解，造成燃油污染地下水范围的扩大，增加污染风险。因此，研究乙醇在地下水中的迁移归宿对预测乙醇混合汽油在地下水中的迁移至关重要。 综合研究现状，本文结合实验含水层物理模型和数值模型，分析研究了乙醇在浅层地下水中的迁移归宿过程，估测了乙醇在迁移过程中的阻滞系数和综合降解速率。研究对现场条件下的相关调查具有一定的指导价值，并能够为乙醇混合汽油污染地下水时制定修复方案提供依据。研究具体结论如下： 通过循环实验，估测得出渗透系数变化范围值为3.60~4.81 m/d，综合平均值为4.07 m/d；开展抽水实验，并利用抽水实验观测数据建立Visual MODFLOW数值模型，通过数值模型反演求参，估测出多孔介质的给水度为0.14；通过示踪实验，估测得出多孔介质的有效孔隙度范围为0.298~0.346，平均值为0.321；纵向弥散系数的范围为1.94×10-3～2.72×10-3 m2/d，平均值为2.45×10-3 m2/d；横向弥散系数范围为1.16×10-4～9.71×10-5 m2/d，平均值为1.09×10-4 m2/d；通过乙醇投注实验，估测得出乙醇在地下水迁移的过程阻滞系数为1，综合降解速率为0.11 d-1；在乙醇的迁移过程中，水动力弥散和土著微生物降解是其归宿的主要因素。 利用Visual MODFLOW和乙醇投注实验观测数据建立了数值模型，通过数值模型将乙醇的迁移归宿过程可视化，并对这一过程进行了分析评价。分析结果认为：乙醇主要以C组取样管为中心线沿水流方向迁移；横向弥散距离有限，主要为B、D组取样管之间（约0.7 m），距离含水层底部0.15～0.60 m范围是乙醇主要的垂向迁移空间；晕核始终在投注孔高度处迁移；其迁移速度约为0.16 m/d；乙醇晕体随迁移时间的增长而减小，但其形态始终呈对称的椭圆形；生物降解对乙醇晕体的作用主要表现为：晕核浓度迅速降解，晕体体积快速减小；在本实验含水层物理模型中，2L浓度为2000mg/L的乙醇可迁移时间约为28天，可迁移距离约为4.48 m。乙醇投注实验数值模型对有效孔隙度最为敏感，其次为降解速率、渗透系数、纵向弥散系数，对给水度不敏感。 |
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太专业了，请修改后使用！！ Ethanol blended gasoline as a new clean energy in many countries to promote the use of. But its leak into the groundwater, as a fuel additive ethanol will lag in the degradation of toxic BTEX, causing fuel the expansion of the groundwater pollution, increased pollution risks. Therefore, the study of ethanol in groundwater migration end of the forecast ethanol blended gasoline in the groundwater migration is essential. Comprehensive Study on the status quo, the paper combining the experimental model of the aquifer physical and numerical model analysis of ethanol in the shallow groundwater migration destination in the process of estimating the ethanol in the block in the process of migration coefficient and integrated degradation rate. Research on the spot investigation under the guidance of a certain value, and ethanol blended gasoline can pollute underground water, provide the basis for developing rehabilitation programme. Research specific conclusions are as follows: Cycle through experiments, estimates that the scope of changes in permeability coefficient value of 3.60 to 4.81 m / d, integrated average of 4.07 m / d; in pumping experiments and experimental use of observation data to establish pumping Visual MODFLOW numerical model, the numerical model - Speech for the Senate and a porous medium estimation of the water supply for 0.14 through tracer experiment, porous media estimated that the effective porosity of the range of 0.298 to 0.346, with a mean of 0.321; vertical diffusion coefficient range of 1.94 × 10 -3 ~ 2.72 × 10-3 m2 / d, with a mean of 2.45 × 10-3 m2 / d; lateral diffusion coefficient of 1.16 × 9.71 × 10-4 to 10-5 m2 / d, with a mean of 1.09 × 10 -4 m2 / d; ethanol bets through experiments, estimates that ethanol in the process of groundwater migration block coefficient is a comprehensive degradation rate of 0.11 d-1 in the migration process of ethanol, and hydrodynamic dispersion Microbial degradation of indigenous its destination is a major factor. And ethanol use Visual MODFLOW betting experimental observation data to establish the numerical model, the numerical model will be the relocation destination ethanol process visualization, and analysis of this process of evaluation. Analysis of the results that: ethanol mainly in Group C for sampling of the direction of water flow along the centerline of migration; horizontal diffusion distance is limited, mainly in groups B and D sampling tubes (approximately 0.7 m) from the aquifer at the bottom of 0.15 ~ 0.60 m Ethanol is the main scope of vertical migration space; halo nuclear always betting hole in the high migration; migration rate of about 0.16 m / d; ethanol migration time with the halo of growth decreased, but its always a symmetrical shape oval; biodegradable ethanol halo on the role of the main performance: concentration rapid degradation of nuclear halo, halo-volume rapid decrease in the physical model of the aquifer, 2 L concentration was 2000 mg / L of ethanol can be relocated time is about 28 days, about 4.48 m distance migration. Ethanol betting experimental numerical model for the effective porosity of the most sensitive, followed by the degradation rate, permeability coefficient, vertical diffusion coefficient of water was not sensitive. |
2楼2008-04-13 18:33:09
jintanqinwei
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3楼2008-04-13 21:43:56