饱和多孔介质中DNAPL污染源区结构及质量溶出
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摘要
为探究重非水相液体(DNAPL)在地下水中的运移和溶出行为,选取四氯乙烯(PCE)为代表,采用透射光法动态监测PCE在二维砂箱中的运移和分布,并以顶空气相色谱法监测其质量溶出,在此基础上通过乙醇冲洗来改变PCE分布,对比分析相应源区结构和溶出浓度的变化.结果表明:PCE的运移以垂向入渗为主,并伴随由毛细管力引起的横向迁移;污染源区面积和溶出浓度的变化具有明显一致性,均先迅速增大而后趋于平稳,由于泄露量小,70.7%的PCE以ganglia态残留在运移路径上.乙醇主要通过增溶作用改变污染源区结构,对PCE的空间展布影响弱,乙醇冲洗后ganglia态PCE占比增至99.6%,GTP值从2.4增至257.随着乙醇冲洗体积的增加,PCE源区面积从100cm~2减至50cm~2,对应溶出浓度从114mg/L减至12mg/L,二者呈较好的线性关系(R~2=0.76).此外,连续监测结果显示,在本研究的实验条件下,无论是否经过乙醇冲洗,PCE污染源区结构和其相应的质量溶出可以在一定时间内(至少16PVs)保持稳定.
To investigate the migration and dissolution of dense non-aqueous phase liquid(DNAPL) in groundwater, tetrachloroethylene(PCE) was selected as the representative in this study. The migration and distribution process of PCE in a two-dimensional(2-D) sandbox were dynamically monitored by light transmission method, while the PCE dissolution was determined using headspace gas chromatograph. Ethanol flushing was then performed to alter the PCE distribution in the sandbox, and the corresponding changes in source zone architecture and dissolution concentration were analysed. Results showed that the migration of PCE was mainly downwards vertical infiltration, accompanied by lateral spreading caused by capillary force. During the migration process, the changes of the PCE source area and the dissolved concentration were obviously consistent, both of which increased rapidly and then stabilized. Due to the small amount of leakage, 70.7% of the PCE was trapped in the migration path and existent as discontinuous ganglia. Ethanol flushing changed the source zone architecture mainly via solubilization, while it exhibited a weak influence on the spatial distribution of PCE. After being flushed with ethanol, the percentage of ganglia PCE increased to 99.6%, and the GTP value increased from 2.4 to 257. With the increase of ethanol flushing volumes, the PCE source zone area decreased from 100 cm~2 to 50 cm~2 and the dissolved concentration decreased from 114 mg/L to 12 mg/L, and the two showed a good relationship(R~2=0.76). In addition, continuous monitoring results showed that in the current study, the source zone architecture and dissolution of PCE could remain stable for a certain period of time(at least 16 PVs), regardless of whether it was flushed with ethanol or not.
To investigate the migration and dissolution of dense non-aqueous phase liquid(DNAPL) in groundwater, tetrachloroethylene(PCE) was selected as the representative in this study. The migration and distribution process of PCE in a two-dimensional(2-D) sandbox were dynamically monitored by light transmission method, while the PCE dissolution was determined using headspace gas chromatograph. Ethanol flushing was then performed to alter the PCE distribution in the sandbox, and the corresponding changes in source zone architecture and dissolution concentration were analysed. Results showed that the migration of PCE was mainly downwards vertical infiltration, accompanied by lateral spreading caused by capillary force. During the migration process, the changes of the PCE source area and the dissolved concentration were obviously consistent, both of which increased rapidly and then stabilized. Due to the small amount of leakage, 70.7% of the PCE was trapped in the migration path and existent as discontinuous ganglia. Ethanol flushing changed the source zone architecture mainly via solubilization, while it exhibited a weak influence on the spatial distribution of PCE. After being flushed with ethanol, the percentage of ganglia PCE increased to 99.6%, and the GTP value increased from 2.4 to 257. With the increase of ethanol flushing volumes, the PCE source zone area decreased from 100 cm~2 to 50 cm~2 and the dissolved concentration decreased from 114 mg/L to 12 mg/L, and the two showed a good relationship(R~2=0.76). In addition, continuous monitoring results showed that in the current study, the source zone architecture and dissolution of PCE could remain stable for a certain period of time(at least 16 PVs), regardless of whether it was flushed with ethanol or not.
引文
[1]高存荣,王俊桃.我国69个城市地下水有机污染特征研究[J].地球学报, 2011,32(5):581-591.Gao C R, Wang J T. Research on groundwater organic contamination characteristics in 69 cities of China[J]. Aacta Ggeoscientia Sinica,2011,32(5):581-591.
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[3]张卫,李丽,林匡飞,等.采用筛板塔吹脱模拟处理四氯乙烯污染地下水[J].中国环境科学, 2012,32(6):1001-1006.Zhang W, Li L, Lin K F, et al. Air stripping in sieve plate tower for the simulated treatment of the groundwater polluted by perchloroethylene[J]. China Environmental Science, 2012,32(6):1001-1006.
[4]程洲,吴吉春,徐红霞,等.DNAPL在透镜体及表面活性剂作用下的运移研究[J].中国环境科学, 2014,34(11):2888-2896.Chen Z, Wu J C, Xu H X, et al. Investigation of the migration characteristic of DNAPL in aquifer with lenses and under the action of surfactant flushing[J]. China Environmental Science, 2014,34(11):2888-2896.
[5] Essaid H I, Bekins B A, Cozzarelli I M. Organic contaminant transport and fate in the subsurface:Evolution of knowledge and understanding[J]. Water Resources Research, 2015,51(7):4861-4902.
[6] Agaoglu B, Copty N K, Scheytt T, et al. Interphase mass transfer between fluids in subsurface formations:A review[J]. Advances in Water Resources, 2015,79:162-194.
[7] Bob M M, Brooks M C, Mravik S C, et al. A modified light transmission visualization method for DNAPL saturation measurements in 2-D models[J]. Advances in Water Resources, 2008,31(5):727-742.
[8] Erning K, Dahmke A, Sch?fer D. Simulation of DNAPL infiltration and spreading behaviour in the saturated zone at varying flow velocities and alternating subsurface geometries[J]. Environmental Earth Sciences, 2012,65(4):1119-1131.
[9]程洲,徐红霞,吴吉春,等.地下水中Tween80对DNAPL运移和分布的影响[J].中国环境科学, 2019,39(3):1068-1077.Chen Z, Xu H X, Wu J C, et al. Effects of Tween 80 in groundwater on DNAPL migration and distribution[J]. China Environmental Science,2019,39(3):1068-1077.
[10]高燕维,郑菲,施小清,等.基于透射光法探讨水流流速对DNAPL运移分布的影响[J].环境科学, 2015,36(7):2532-2539.Gao Y W, Zheng F, SHI X Q, et al. Laboratory investigation of DNAPL migration behavior and distribution at varying flow velocities based on light transmission method[J]. Environmental Science,2015,36(7):2532-2539.
[11]郑菲,高燕维,施小清,等.地下水流速及介质非均质性对重非水相流体运移的影响[J].水利学报, 2015,46(8):925-933.Zheng F, Gao Y W, SHI X Q, et al. Influence of groundwater flow velocity and geological heterogeneity on DNAPL migration in saturated porous media[J]. Journal of Hydraulic Engineering, 2015,46(8):925-933.
[12] Taylor T P, Pennell K D, Abriola L M, et al. Surfactant enhanced recovery of tetrachloroethylene from a porous medium containing low permeability lenses:1. Experimental studies[J]. Journal of Contaminant Hydrology, 2001,48(3/4):325-350.
[13] O'Carroll D M, Sleep B E. Hot water flushing for immiscible displacement of a viscous NAPL[J]. Journal of Contaminant Hydrology, 2007,91(3):247-266.
[14] Molnar I L, O'Carroll D M, Gerhard J I. Impact of surfactant-induced wettability alterations on DNAPL invasion in quartz and iron oxidecoated sand systems[J]. Journal of Contaminant Hydrology, 2011,119(1-4):1-12.
[15] Wu B, Li H, Du X, et al. Correlation between DNAPL distribution area and dissolved concentration in surfactant enhanced aquifer remediation effluent:A two-dimensional flow cell study[J].Chemosphere, 2016,144:2142-2149.
[16]伍斌,杨宾,李慧颖,等.表面活性剂强化抽出处理含水层中DNAPL污染物的去除特征[J].环境工程学报, 2014,8(5):1956-1964.Wu B, Yang B, Li H Y, et al. Removal characteristic of DNAPL contaminants in surfactant enhanced aquifer remediation[J]. Chinese Journal of Environmental Engineering, 2014,8(5):1956-1964.
[17]郑菲,高燕维,孙媛媛,等.污染源区结构特征对Tween 80去除DNAPL效果的影响[J].中国环境科学, 2016,36(7):2035-2042.Zheng F, Gao Y W, Sun Y Y, et al. The influence of source-zone architecture on DNAPL removal by Tween 80 flushing[J]. China Environmental Science, 2016,36(7):2035-2042.
[18] Nambi I M, Powers S E. NAPL dissolution in heterogeneous systems:an experimental investigation in a simple heterogeneous system[J].Journal of Contaminant Hydrology, 2000,44(2):161-184.
[19] Difilippo E L, Brusseau M L. Relationship between mass-flux reduction and source-zone mass removal:analysis of field data[J].Journal of Contaminant Hydrology, 2008,98(1):22-35.
[20] Page J W, Soga K, Illangasekare T. The significance of heterogeneity on mass flux from DNAPL source zones:an experimental investigation[J]. Journal of Contaminant Hydrology, 2007,94(3):215-234.
[21] Difilippo E L, Carroll K C, Brusseau M L. Impact of organic-liquid distribution and flow-field heterogeneity on reductions in mass flux[J]. Journal of Contaminant Hydrology, 2010,115(1):14-25.
[22]李洪,李鑫钢,徐世民,等.饱和区中非水相有机物溶解的实验研究[J].化学工程, 2008,36(4):49-52.Li H, Li X G, Xu S M, et al. Experimental study of non-aqueous phase liquids dissolution in saturated zone[J]. Chemical Engineering,2008,36(4):49-52.
[23]郭琼泽,张烨,姜蓓蕾,等.表面活性剂增强修复地下水中PCE的砂箱实验及模拟[J].中国环境科学, 2018,38(9):200-207.Guo Q Z, Zhang Y, Jiang B L, et al. Experiment and numerical simulation of surfactant-enhanced aquifer remediation in PCE contaminated laboratory sandbox[J]. China Environmental Science,2018,38(9):200-207.
[24] Ye S, Sleep B E, Chien C. The impact of methanogenesis on flow and transport in coarse sand[J]. Journal of Contaminant Hydrology,2009,103(1):48-57.
[25] Seyedabbasi M A, Farthing M W, Imhoff P T, et al. WITHDRAWN:Influence of porous media heterogeneity on NAPL dissolution fingering and upscaled mass transfer[J]. Water Resources Research,2013,47(12):W08507.
[26] Luciano A, Viotti P, Papini M P. Laboratory investigation of DNAPL migration in porous media.[J]. Journal of Hazardous Materials, 2010,176(1):1006-1017.
[27] Altiok E, Koos R, Schr?der J, et al. Comparison of two-dimensional and three-dimensional imaging techniques for measurement of aortic annulus diameters before transcatheter aortic valve implantation[J].Heart, 2011,97(19):1578.
[28] Fagerlund F, Illangasekare T H, Niemi A. Nonaqueous-phase liquid infiltration and immobilization in heterogeneous media:1.Experimental methods and two-layered reference case[J]. Vadose Zone Journal, 2007,6(3):471-482.
[29] Schroth M H, Istok J D, Ahearn S J, et al. Characterization of miller-similar silica sands for laboratory hydrologic studies[J]. Soil Science Society of America Journal, 1996,60(5):1331-1339.
[30] Totten C, Annable M, Jawitz J, et al. Fluid and porous media property effects on dense nonaqueous phase liquid migration and contaminant mass flux[J]. Environmental Science&Technology, 2007,41(5):1622.
[31] Suchomel E J, Pennell K D. Reductions in contaminant mass discharge following partial mass removal from DNAPL source zones[J]. Environmental Science&Technology, 2006,40(19):6110-6116.
[32] Tick G R, Harvell J R, Murgulet D. Intermediate-scale investigation of enhanced-solubilization agents on the dissolution and removal of a multicomponent dense nonaqueous phase liquid(DNAPL)Source[J].Water Air&Soil Pollution, 2015,226(11):371.
[33] Falta R W. Using phase diagrams to predict the performance of cosolvent floods for NAPL remediation[J]. Groundwater Monitoring&Remediation, 1998,18(3):94-102.
[2]刘菲,王苏明,陈鸿汉.欧美地下水有机污染调查评价进展[J].地质通报, 2010,29(6):907-917.Liu F, Wang S M, Chen H H. Progress of investigation and evaluation on groundwater organic contaminants in western countries[J].Geological Bulletin of China, 2010,29(6):907-917.
[3]张卫,李丽,林匡飞,等.采用筛板塔吹脱模拟处理四氯乙烯污染地下水[J].中国环境科学, 2012,32(6):1001-1006.Zhang W, Li L, Lin K F, et al. Air stripping in sieve plate tower for the simulated treatment of the groundwater polluted by perchloroethylene[J]. China Environmental Science, 2012,32(6):1001-1006.
[4]程洲,吴吉春,徐红霞,等.DNAPL在透镜体及表面活性剂作用下的运移研究[J].中国环境科学, 2014,34(11):2888-2896.Chen Z, Wu J C, Xu H X, et al. Investigation of the migration characteristic of DNAPL in aquifer with lenses and under the action of surfactant flushing[J]. China Environmental Science, 2014,34(11):2888-2896.
[5] Essaid H I, Bekins B A, Cozzarelli I M. Organic contaminant transport and fate in the subsurface:Evolution of knowledge and understanding[J]. Water Resources Research, 2015,51(7):4861-4902.
[6] Agaoglu B, Copty N K, Scheytt T, et al. Interphase mass transfer between fluids in subsurface formations:A review[J]. Advances in Water Resources, 2015,79:162-194.
[7] Bob M M, Brooks M C, Mravik S C, et al. A modified light transmission visualization method for DNAPL saturation measurements in 2-D models[J]. Advances in Water Resources, 2008,31(5):727-742.
[8] Erning K, Dahmke A, Sch?fer D. Simulation of DNAPL infiltration and spreading behaviour in the saturated zone at varying flow velocities and alternating subsurface geometries[J]. Environmental Earth Sciences, 2012,65(4):1119-1131.
[9]程洲,徐红霞,吴吉春,等.地下水中Tween80对DNAPL运移和分布的影响[J].中国环境科学, 2019,39(3):1068-1077.Chen Z, Xu H X, Wu J C, et al. Effects of Tween 80 in groundwater on DNAPL migration and distribution[J]. China Environmental Science,2019,39(3):1068-1077.
[10]高燕维,郑菲,施小清,等.基于透射光法探讨水流流速对DNAPL运移分布的影响[J].环境科学, 2015,36(7):2532-2539.Gao Y W, Zheng F, SHI X Q, et al. Laboratory investigation of DNAPL migration behavior and distribution at varying flow velocities based on light transmission method[J]. Environmental Science,2015,36(7):2532-2539.
[11]郑菲,高燕维,施小清,等.地下水流速及介质非均质性对重非水相流体运移的影响[J].水利学报, 2015,46(8):925-933.Zheng F, Gao Y W, SHI X Q, et al. Influence of groundwater flow velocity and geological heterogeneity on DNAPL migration in saturated porous media[J]. Journal of Hydraulic Engineering, 2015,46(8):925-933.
[12] Taylor T P, Pennell K D, Abriola L M, et al. Surfactant enhanced recovery of tetrachloroethylene from a porous medium containing low permeability lenses:1. Experimental studies[J]. Journal of Contaminant Hydrology, 2001,48(3/4):325-350.
[13] O'Carroll D M, Sleep B E. Hot water flushing for immiscible displacement of a viscous NAPL[J]. Journal of Contaminant Hydrology, 2007,91(3):247-266.
[14] Molnar I L, O'Carroll D M, Gerhard J I. Impact of surfactant-induced wettability alterations on DNAPL invasion in quartz and iron oxidecoated sand systems[J]. Journal of Contaminant Hydrology, 2011,119(1-4):1-12.
[15] Wu B, Li H, Du X, et al. Correlation between DNAPL distribution area and dissolved concentration in surfactant enhanced aquifer remediation effluent:A two-dimensional flow cell study[J].Chemosphere, 2016,144:2142-2149.
[16]伍斌,杨宾,李慧颖,等.表面活性剂强化抽出处理含水层中DNAPL污染物的去除特征[J].环境工程学报, 2014,8(5):1956-1964.Wu B, Yang B, Li H Y, et al. Removal characteristic of DNAPL contaminants in surfactant enhanced aquifer remediation[J]. Chinese Journal of Environmental Engineering, 2014,8(5):1956-1964.
[17]郑菲,高燕维,孙媛媛,等.污染源区结构特征对Tween 80去除DNAPL效果的影响[J].中国环境科学, 2016,36(7):2035-2042.Zheng F, Gao Y W, Sun Y Y, et al. The influence of source-zone architecture on DNAPL removal by Tween 80 flushing[J]. China Environmental Science, 2016,36(7):2035-2042.
[18] Nambi I M, Powers S E. NAPL dissolution in heterogeneous systems:an experimental investigation in a simple heterogeneous system[J].Journal of Contaminant Hydrology, 2000,44(2):161-184.
[19] Difilippo E L, Brusseau M L. Relationship between mass-flux reduction and source-zone mass removal:analysis of field data[J].Journal of Contaminant Hydrology, 2008,98(1):22-35.
[20] Page J W, Soga K, Illangasekare T. The significance of heterogeneity on mass flux from DNAPL source zones:an experimental investigation[J]. Journal of Contaminant Hydrology, 2007,94(3):215-234.
[21] Difilippo E L, Carroll K C, Brusseau M L. Impact of organic-liquid distribution and flow-field heterogeneity on reductions in mass flux[J]. Journal of Contaminant Hydrology, 2010,115(1):14-25.
[22]李洪,李鑫钢,徐世民,等.饱和区中非水相有机物溶解的实验研究[J].化学工程, 2008,36(4):49-52.Li H, Li X G, Xu S M, et al. Experimental study of non-aqueous phase liquids dissolution in saturated zone[J]. Chemical Engineering,2008,36(4):49-52.
[23]郭琼泽,张烨,姜蓓蕾,等.表面活性剂增强修复地下水中PCE的砂箱实验及模拟[J].中国环境科学, 2018,38(9):200-207.Guo Q Z, Zhang Y, Jiang B L, et al. Experiment and numerical simulation of surfactant-enhanced aquifer remediation in PCE contaminated laboratory sandbox[J]. China Environmental Science,2018,38(9):200-207.
[24] Ye S, Sleep B E, Chien C. The impact of methanogenesis on flow and transport in coarse sand[J]. Journal of Contaminant Hydrology,2009,103(1):48-57.
[25] Seyedabbasi M A, Farthing M W, Imhoff P T, et al. WITHDRAWN:Influence of porous media heterogeneity on NAPL dissolution fingering and upscaled mass transfer[J]. Water Resources Research,2013,47(12):W08507.
[26] Luciano A, Viotti P, Papini M P. Laboratory investigation of DNAPL migration in porous media.[J]. Journal of Hazardous Materials, 2010,176(1):1006-1017.
[27] Altiok E, Koos R, Schr?der J, et al. Comparison of two-dimensional and three-dimensional imaging techniques for measurement of aortic annulus diameters before transcatheter aortic valve implantation[J].Heart, 2011,97(19):1578.
[28] Fagerlund F, Illangasekare T H, Niemi A. Nonaqueous-phase liquid infiltration and immobilization in heterogeneous media:1.Experimental methods and two-layered reference case[J]. Vadose Zone Journal, 2007,6(3):471-482.
[29] Schroth M H, Istok J D, Ahearn S J, et al. Characterization of miller-similar silica sands for laboratory hydrologic studies[J]. Soil Science Society of America Journal, 1996,60(5):1331-1339.
[30] Totten C, Annable M, Jawitz J, et al. Fluid and porous media property effects on dense nonaqueous phase liquid migration and contaminant mass flux[J]. Environmental Science&Technology, 2007,41(5):1622.
[31] Suchomel E J, Pennell K D. Reductions in contaminant mass discharge following partial mass removal from DNAPL source zones[J]. Environmental Science&Technology, 2006,40(19):6110-6116.
[32] Tick G R, Harvell J R, Murgulet D. Intermediate-scale investigation of enhanced-solubilization agents on the dissolution and removal of a multicomponent dense nonaqueous phase liquid(DNAPL)Source[J].Water Air&Soil Pollution, 2015,226(11):371.
[33] Falta R W. Using phase diagrams to predict the performance of cosolvent floods for NAPL remediation[J]. Groundwater Monitoring&Remediation, 1998,18(3):94-102.
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