LaRiviere Daniel J, Autenrieth Robin L, Bonner James S
Department of Civil Engineering, Texas A and M University, College Station, TX 77843-3136, USA.
Water Res. 2003 Aug;37(14):3307-18. doi: 10.1016/S0043-1354(03)00134-9.
Redox potentials and sediment porewater parameters were measured around the periphery of a small cove along the San Jacinto River in Texas throughout a crude oil and chemical dispersant remediation study to distinguish normal dynamics from those caused as a response to stress from oil deposition and chemical treatment and subsequent recovery. Before the application of oil and treatments, sediments displayed average redox potentials of 0-350 mV when not submerged. Within 2 days of the applications, redox potentials in these plots decreased and exhibited a range from -200 to 0 mV for a duration of 5 weeks. Applied treatments significantly reduced the sediments of the wetland. Reduced redox potentials were indicative of the corresponding sulfate reduction that was also found to be significant following the oil application. GC/MS and MPN analysis indicates this reduction is due to biological oxidation of the crude oil components by alkane- and PAH-degraders in these surficial sediments and validates the usefulness of the redox measurement as an indicator for carbon oxidation. Increases in aqueous phase total organic and inorganic carbon coincided with a decrease in pH shortly after the applications, suggesting incomplete mineralization and the generation of organic acids. While dissolved ferrous iron and sulfide have been found to be good indicators of reductive processes in petroleum-contaminated aquifer sediments; that was not the case in this wetland study. Despite the disappearance of sulfate following the oil application, dissolved ferrous iron and sulfide concentrations remained at pre-application levels suggesting the formation of mackinawite and/or pyrite. The transient exposure of surface sediments to oxygen complicates the consideration of potential solid phase pathways since aqueous iron may be removed by precipitation when oxidized or reduced, making porewater iron a poor indicator for terminal electron accepting processes in wetland sediments.
在德克萨斯州圣哈辛托河沿岸一个小海湾周边，进行了一项原油和化学分散剂修复研究，期间测量了氧化还原电位和沉积物孔隙水参数，以区分正常动态与因油类沉积、化学处理及后续恢复产生的应激反应所导致的动态变化。在施加油类和处理之前，未被淹没时沉积物的平均氧化还原电位为0 - 350毫伏。施加后的2天内，这些区域的氧化还原电位下降，在5周时间内呈现出 - 200至0毫伏的范围。施加的处理显著减少了湿地的沉积物。氧化还原电位降低表明相应的硫酸盐还原，在施加油类后也发现这种还原很显著。气相色谱/质谱联用仪（GC/MS）和最大可能数（MPN）分析表明，这种还原是由于这些表层沉积物中烷烃和多环芳烃降解菌对原油成分的生物氧化，验证了氧化还原测量作为碳氧化指标的有用性。施加后不久，水相总有机碳和无机碳增加，同时pH值下降，表明矿化不完全且产生了有机酸。虽然已发现溶解的亚铁和硫化物是石油污染含水层沉积物中还原过程的良好指标；但在这项湿地研究中并非如此。尽管施加油类后硫酸盐消失，但溶解的亚铁和硫化物浓度仍保持在施加前的水平，这表明形成了硫铁矿和/或黄铁矿。表层沉积物对氧气的短暂暴露使潜在固相途径的考虑变得复杂，因为水相铁在氧化或还原时可能通过沉淀被去除，使得孔隙水铁成为湿地沉积物中终端电子接受过程的不良指标。
