Journal of Hydrology ( IF 6.4 ) Pub Date : 2021-02-24 , DOI: 10.1016/j.jhydrol.2021.126122 Shuai Shao , Xiujun Guo , Chang Gao , Huifang Liu
During the investigation of aged hydrocarbon contaminated sites using electrical resistivity tomography (ERT), the low-resistivity anomalies in the detection profile have been widely considered to be caused by the hydrocarbon degradation by-products. However, these low-resistivity anomalies are a comprehensive reflection of the formation’s electrical characteristics. In this study, we used ERT and geochemical methods to investigate a hydrocarbon-contaminated site that has been abandoned for more than 30 years. There are several obvious low resistivity anomalies in the site, which are related to hydrocarbon mineralization. Based on the law of Waxman and Smits, a petrophysical relationship formula suitable for this specific site was fitted, and the true resistivity after inversion was input into the formula to calculate the pore water resistivity. The electrolytic conduction contribution of the pore water was isolated, and the distribution of the by-product plume was determined based on the electrolytic conduction contribution of the pore water. Based on mineralogical identification and geochemical data analysis, the biogeochemical model of hydrocarbon mineralization was clarified. The degradation by-products (Fe2+ and H+) are the controlling factors that lead to changes in the groundwater resistivity. Based on electrochemical experiments and titration analysis experiments, the quantitative relationship between the low resistivity anomalies of the pore water and the degradation by-products (Fe2+ and H+) was established, and the biodegradation model was used to calculate the hydrocarbon degradation corresponding to the by-product plume. The results show that the hydrocarbon degradation corresponding to the by-product plume determined from the ERT detection results in the selected study area is approximately 2.8% of the total hydrocarbon content. Although this is a rough estimate based on a small amount of discrete geochemical data and ERT detection results, it improves our understanding of the natural attenuation state of hydrocarbon-contaminated sites and provides convincing data to support future estimations of the site's natural attenuation time.
中文翻译:
在老化的碳氢化合物污染场地中,副产品羽流的电阻率分布与碳氢化合物降解之间的定量关系
在使用电阻层析成像(ERT)研究老化的碳氢化合物污染地点的过程中,检测剖面中的低电阻率异常被广泛认为是由碳氢化合物降解副产物引起的。但是,这些低电阻率异常是对地层电学特征的全面反映。在这项研究中,我们使用了ERT和地球化学方法来调查一个已被废弃30多年的碳氢化合物污染的地点。该地点有几个明显的低电阻率异常,与烃的矿化有关。根据Waxman和Smits定律,拟合了适合该特定部位的岩石物理关系公式,并将反演后的真实电阻率输入公式中,以计算孔隙水电阻率。分离出孔隙水的电解传导贡献,并基于孔隙水的电解传导贡献确定副产物羽流的分布。在矿物学鉴定和地球化学数据分析的基础上,阐明了油气成矿的生物地球化学模型。降解副产物(铁2+和H +)是导致地下水电阻率变化的控制因素。基于电化学实验和滴定分析实验,孔隙水的低电阻率异常与降解副产物(Fe 2+和H +),然后使用生物降解模型计算与副产物羽流相对应的碳氢化合物降解量。结果表明,在所选研究区域中,根据ERT检测结果确定的与副产物羽流相对应的碳氢化合物降解量约为总碳氢化合物含量的2.8%。尽管这是基于少量离散地球化学数据和ERT检测结果得出的粗略估计,但它可以增进我们对碳氢化合物污染站点自然衰减状态的理解,并提供令人信服的数据以支持对该站点自然衰减时间的未来估计。