Department of Civil and Environmental Engineering, Rice University, MS-317, 6100 Main St., Houston, TX 77005, USA.
J Contam Hydrol. 2010 Apr 1;113(1-4):66-76. doi: 10.1016/j.jconhyd.2010.02.002. Epub 2010 Feb 6.
The effects of five fuel alcohols (methanol, ethanol, 1-propanol, iso-butanol and n-butanol) on the natural attenuation of benzene were compared using a previously developed numerical model (General Substrate Interaction Module--GSIM) and a probabilistic sensitivity analysis. Simulations with a 30 gal dissolving LNAPL (light non-aqueous phase liquid) source consisting of a range of gasoline blends (10% and 85% v:v alcohol content) suggest that all fuel alcohols can hinder the natural attenuation of benzene, due mainly to accelerated depletion of dissolved oxygen and a decrease in the specific degradation rate for benzene (due to catabolite repression and metabolic flux dilution). Simulations for blends with 10% alcohol, assuming a homogeneous sandy aquifer, inferred maximum benzene plume elongations (relative to a regular gasoline release) of 26% for ethanol, 47% for iso-butanol, 147% for methanol, 188% for 1-propanol, and 265% for n-butanol. The corresponding elongation percentages for blends with 85% alcohol were generally smaller (i.e., 25%, 54%, 135%, 163%, and 181%, respectively), reflecting a lower content of benzene in the simulated release. Benzene plume elongation and longevity were more pronounced in the presence of alcohols that biodegrade slower (e.g., propanol and n-butanol), forming longer and more persistent alcohol plumes. Conversely, ethanol and iso-butanol exhibited the lowest potential to hinder the natural attenuation of benzene, illustrating the significant effect that a small difference in chemical structure (e.g., isomers) can have on biodegradation. Overall, simulations were highly sensitive to site-specific biokinetic coefficients for alcohol degradation, which forewarns against generalizations about the level of impact of specific fuel alcohols on benzene plume dynamics.
使用先前开发的数值模型（通用基质相互作用模块-GSIM）和概率敏感性分析，比较了五种燃料醇（甲醇、乙醇、1-丙醇、异丁醇和正丁醇）对苯自然衰减的影响。用一个 30 加仑溶解的 LNAPL（轻质非水相液体）源进行的模拟，该源由一系列汽油混合物（10%和 85%v:v 醇含量）组成，结果表明所有燃料醇都可以阻碍苯的自然衰减，主要原因是溶解氧的加速消耗和苯的特定降解速率下降（由于代谢物抑制和代谢通量稀释）。对于含有 10%醇的混合物进行模拟，假设为均质砂质含水层，推断出乙醇的最大苯羽流伸长率（相对于常规汽油释放）为 26%，异丁醇为 47%，甲醇为 147%，1-丙醇为 188%，正丁醇为 265%。对于含 85%醇的混合物，伸长率百分比通常较小（即，分别为 25%、54%、135%、163%和 181%），反映出模拟释放中苯的含量较低。在降解较慢的醇（如丙醇和正丁醇）存在下，苯羽流的伸长和持续时间更为明显，形成了更长和更持久的醇羽流。相反，乙醇和异丁醇对阻碍苯的自然衰减的潜力最低，说明了化学结构（如异构体）的微小差异对生物降解的显著影响。总的来说，模拟对醇降解的特定现场生物动力学系数非常敏感，这警告人们不要对特定燃料醇对苯羽流动力学的影响程度进行一般性推断。
