Brown Derick G, Komlos John, Jaffé Peter R
Department of Civil & Environmental Engineering, Lehigh University, 13 East Packer Avenue, Bethlehem, Pennsylvania 18015, USA.
Environ Sci Technol. 2005 May 1;39(9):3069-76. doi: 10.1021/es048613p.
Dissolved hydrogen concentrations, in conjunction with other geochemical indicators, are becoming an accepted means to determine terminal electron acceptor processes (TEAPs) in groundwater aquifers. Aqueous hydrogen concentrations have been found to fall within specific ranges under methanogenic, sulfate-reducing, iron-reducing, and denitrification conditions. Although hydrogen is gaining in acceptance for determining subsurface TEAPs, there is a dearth of data with regards to the kinetic coefficients for hydrogen utilization in the presence or absence of an additional electron donor under different TEAPs. This study expands the kinetic data for hydrogen utilization through a series of batch experiments, which were conducted to study the utilization of acetate and hydrogen by Geobacter sulfurreducens under iron-reducing conditions. The results of these experiments indicate that the kinetic coefficients (cell yield and first-order degradation rate) describing the rate of hydrogen utilization by G. sulfurreducens under iron-reducing conditions correlate energetically with the coefficients found in previous experiments under methanogenic and sulfate-reducing conditions. In addition, with acetate and hydrogen as simultaneous electron donors, there is slight inhibition between the two electron donors for G. sulfurreducens, and this can be modeled through competitive inhibition terms in the classic Monod formulation. Finally, a key result of this study is that the TEAP-dependent hydrogen concentration in aquifers is not related solely to the microbial kinetics of the hydrogen-consuming organisms as previously suggested but is affected by the multi-substrate kinetics of hydrogen being consumed simultaneously with other electron donors as well as the availability of the electron acceptor.
溶解氢浓度与其他地球化学指标相结合，正成为确定地下水含水层中终端电子受体过程（TEAPs）的一种公认方法。已发现，在产甲烷、硫酸盐还原、铁还原和反硝化条件下，水中氢浓度会落在特定范围内。尽管氢在确定地下TEAPs方面越来越被认可，但关于在不同TEAPs条件下，有无额外电子供体时氢利用的动力学系数的数据却很匮乏。本研究通过一系列批次实验扩展了氢利用的动力学数据，这些实验旨在研究在铁还原条件下，硫还原地杆菌对乙酸盐和氢的利用情况。这些实验结果表明，描述硫还原地杆菌在铁还原条件下氢利用速率的动力学系数（细胞产量和一级降解速率）与之前在产甲烷和硫酸盐还原条件下实验中发现的系数在能量上相关。此外，当乙酸盐和氢作为同时存在的电子供体时，对于硫还原地杆菌来说，这两种电子供体之间存在轻微抑制作用，并且这可以通过经典莫诺德公式中的竞争抑制项来建模。最后，本研究的一个关键结果是，含水层中依赖于TEAP的氢浓度并非如之前所认为的那样仅与耗氢生物体的微生物动力学有关，而是受到与其他电子供体同时被消耗的氢的多底物动力学以及电子受体可用性的影响。
