为研究自然条件下饱和含水层中1,2-DCA(1,2-二氯乙烷)的自然衰减过程及该过程中含水层氧化还原环境的变化特征,利用室内连续水流土柱模拟饱和含水层,研究生物降解作用对1,2-DCA自然衰减的贡献以及饱和含水层环境条件的动态变化规律.初始ρ(1,2-DCA)为50 mg/L,模拟地下水流速为450 μL/min,模拟试验连续进行30 d,分别监测ρ(1,2-DCA)和水环境指标.结果表明,1,2-DCA自然衰减的一级速率常数为0.068 9 d-1,其中生物降解作用的贡献率为6.34％.1,2-DCA自然衰减过程中,NO3-首先充当生物降解的电子受体,随后Fe3、SO42-依次发生反应,土柱内部不同高度出现了氧化还原分带,分别是硫酸盐还原带、铁盐还原带、硝酸盐还原带.%Redox condition in saturated aquifers is one of the significant factors influencing natural attenuation of 1,2-Dichloroethane (1 , 2-DCA). In order to investigate the natural attenuation process of 1 ,2-DCA and its related redox environment variation in a saturated aquifer, a continuous-flow simulation column system was operated in the laboratory. The contribution of biodegradation and the dynamic variation of the redox conditions in the aquifer were studied. The initial concentration of 1 ,2-DCA was set to 50 mg/L. The velocity of groundwater flow was simulated at a rate of 450 μL/min. A 30 day simulation was conducted, with samples taken every seven days to monitor variation of pollutant concentrations and various redox indicators in the aquifer. The results showed that the estimated first-order decay constant was 0. 0689 d-1 , and the contribution of biodegradation to natural attenuation was 6. 34% . During the natural attenuation process, NO3- was first taken as the dominant electronic acceptor, followed by Fe3 + and SO42- . Sequential redox zones (sulfate-reducing zone, iron-reducing zone and nitrate-reducing zone, respectively) were observed in the aquifer columns at different distances from the water inlet.
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