Williams Kenneth H, Kemna Andreas, Wilkins Michael J, Druhan Jennifer, Arntzen Evan, N'Guessan A Lucie, Long Philip E, Hubbard Susan S, Banfield Jillian F
Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
Environ Sci Technol. 2009 Sep 1;43(17):6717-23. doi: 10.1021/es900855j.
Understanding how microorganisms alter their physical and chemical environment during bioremediation is hindered by our inability to resolve subsurface microbial activity with high spatial resolution. Here we demonstrate the use of a minimally invasive geophysical technique to monitor stimulated microbial activity during acetate amendment in an aquifer near Rifle, Colorado. During electrical induced polarization (IP) measurements, spatiotemporal variations in the phase response between imposed electric current and the resultant electric field correlated with changes in groundwater geochemistry accompanying stimulated iron and sulfate reduction and sulfide mineral precipitation. The magnitude of the phase response varied with measurement frequency (0.125 and 1 Hz) and was dependent upon the dominant metabolic process. The spectral effect was corroborated using a biostimulated column experiment containing Rifle sediments and groundwater. Fluids and sediments recovered from regions exhibiting an anomalous phase response were enriched in Fe(II), dissolved sulfide, and cell-associated FeS nanoparticles. The accumulation of mineral precipitates and electroactive ions altered the ability of pore fluids to conduct electrical charge, accounting for the anomalous IP response and revealing the usefulness of multifrequency IP measurementsfor monitoring mineralogical and geochemical changes accompanying stimulated subsurface bioremediation.
由于我们无法以高空间分辨率解析地下微生物活动，因此了解微生物在生物修复过程中如何改变其物理和化学环境受到了阻碍。在此，我们展示了一种微创地球物理技术的应用，用于监测科罗拉多州莱夫尔附近含水层中醋酸盐添加期间受刺激的微生物活动。在电诱导极化（IP）测量期间，施加电流与合成电场之间的相位响应的时空变化与伴随受刺激的铁和硫酸盐还原以及硫化物矿物沉淀的地下水地球化学变化相关。相位响应的幅度随测量频率（0.125和1赫兹）而变化，并取决于主要的代谢过程。使用包含莱夫尔沉积物和地下水的生物刺激柱实验证实了光谱效应。从呈现异常相位响应的区域回收的流体和沉积物富含Fe(II)、溶解的硫化物和与细胞相关的FeS纳米颗粒。矿物沉淀物和电活性离子的积累改变了孔隙流体传导电荷的能力，这解释了异常的IP响应，并揭示了多频IP测量对于监测伴随受刺激的地下生物修复的矿物学和地球化学变化的有用性。
