Flow field dynamics and high ethanol content in gasohol blends enhance BTEX migration and biodegradation in groundwater
Flow field dynamics and high ethanol content in gasohol blends enhance BTEX migration and biodegradation in groundwater
复制标题
DOI：
10.1016/j.jconhyd.2019.01.003
复制
发表时间：
2019-04-01
影响因子：
3.6
通讯作者：
Miotlinski, Konrad
中科院分区：
文献类型：
--
作者：
Rama, Fabrizio;Ramos, Debora Toledo;Miotlinski, Konrad
乙醇汽油溢出物可能很容易通过土壤柱下降，并随着污染物溶解到地下水中而影响敏感的受体。汽油制剂通常与乙醇混合以减轻与化石燃料相关的环境和经济问题。然而，添加到汽油中的乙醇的量和地下水水力状况可以显着影响BTEX羽动态和寿命。在这项研究中，两个长期（5年和10年）的现场规模的乙醇汽油释放乙醇含量分别为85%（E85）和24%（E24），分别进行了评估，以辨别不同的动力学所经历的乙醇汽油混合物。统计，地球化学，微生物和趋势的方法来估计地下水流量的变化对乙醇和溶解BTEX运输的影响，以及相关的生物降解率不同的汽油混合溢出。乙醇和BTEX地下水流量进行了量化的突破曲线特征，羽质心位置和蔓延，源消耗和质量降解率。此外，还对溴化物迁移进行了评价，以说明流动驱动溶解的贡献。结果表明，大量的乙醇沿着快速和动态的流产生冲洗行为，增强BTEX的溶解，迁移（垂直和水平）和浓度在地下水中。相对于E24位点，E85中较高量的乙醇增强了BTEX的溶解（和生物利用度），并导致更快的生物降解速率，这可以通过共溶效应和代谢通量稀释来解释。因此，流场动力学和乙醇混合物中的高乙醇含量增强了BTEX在乙醇汽油污染场地中的迁移和生物降解。这些因素的平衡对于确定污染物在现场的归宿和迁移至关重要。这些研究结果表明，水力制度应在空间和时间上的特点，以支持适当的监测计划和补救策略的乙醇汽油泄漏的决定。
Gasohol spills may easily descend through the soil column down and impact sensitive receptors as contaminants dissolve into the groundwater. Gasoline formulations are commonly blended with ethanol to alleviate environmental and economic issues associated with fossil fuels. However, the amount of ethanol added to gasoline and the groundwater hydraulic regime can significantly affect BTEX plume dynamics and lifespan. In this study, two long-term (5 and 10 years) field-scale gasohol releases with ethanol contents of 85% (E85) and 24% (E24), respectively, were assessed to discern the different dynamics undergone by gasohol blends. Statistical, geochemical, microbiological and trend approaches were employed to estimate the influence of groundwater flow variations on ethanol and dissolved BTEX transport, and the associated biodegradation rates of different gasohol blend spills. Ethanol and BTEX groundwater flow were quantified in terms of breakthrough curve characteristics, plume centroid positions and spreading, source depletion and mass degradation rates. In addition, bromide migration was evaluated to address the contribution of flow-driven dissolution. Results revealed that the high amount of ethanol along with a fast and dynamic flow exerted a flushing behavior that enhanced BTEX dissolution, migration (vertical and horizontal) and concentrations in groundwater. The higher amount of ethanol in E85 enhanced BTEX dissolution (and bioavailability) relative to E24 site and led to faster biodegradation rates, which can be explained by the cosolvency effect and metabolic flux dilution. Therefore, flow field dynamics and high ethanol content in gasohol blends enhance BTEX migration and biodegradation in gasohol contaminated sites. The balance of these factors is crucial to determine fate and transport of contaminants in field sites. These findings suggest that hydraulic regime should be spatially and temporally characterized to support decisions on appropriate monitoring plan and remedial strategies for gasohol spills.