Collaborative Research: Investigating the impact of microbial interactions with geologic media on geophysical properties: Implications for assessing geomicrobiological prosseses

细菌已被证明在地质过程中发挥着重要作用，然而，它们在改变岩石地球物理性质方面的作用还没有被很好地了解，也没有得到彻底的研究。这个项目是密苏里大学罗拉分校、罗格斯大学和西密歇根大学的研究人员之间为期三年的合作。其目的是了解和测量微生物与地质介质相互作用引起的地球物理变化。该项目的具体目标是进行实验室和野外研究，以调查：(1)微生物细胞浓度和生物膜形成增加对土壤和沉积物电学性质的影响；(2)微生物活动的代谢副产物，如生物表面活性剂和有机酸对地球物理电学测量的影响；(3)微生物-矿物相互作用引起的岩石物理性质(例如渗透率、孔隙度、表面积)的潜在变化；以及(4)具有异常地球物理特征的沉积物中微生物群落及其结构、动力学和组合的差异。第一阶段的工作将包括测量实验室柱反应器中细菌细胞、生物膜和有机酸的电信号。最终的反应器产品将用显微摄影技术成像，以调查生物膜的分布和孔几何形状的变化。第二阶段的工作将集中于测量反应堆沉积物的物理性质(形成系数、表面积、孔隙度、渗透率)。这项工作的结果将有助于建立一个数据库，将电、物理和生化参数联系起来，可用于现场输入数据的地球物理建模。该计划的最后阶段将集中于现场测量和观察沉积物电导率的变化如何与地质材料的微生物蚀变有关。这些分析将在核心和实地范围内进行。这项研究将为发展地球物理学作为研究地球微生物过程的工具奠定基础。更广泛和潜在的社会效益包括开发可用于监测和评估地下水含水层的生物定居和近地下溶解污染物的微生物矿化的地球物理技术。教育和推广举措将侧重于学生的参与，并在各国的MAD国际会议上向更广泛的地球物理和生物地球科学界宣传由学生主导的生物地球物理学。

Bacteria have been shown to play an important role in geologic processes, however, their role in altering geophysical properties of rocks is not well understood, nor has it been thoroughly investigated. This project is a three-year collaboration between researchers at the University of Missouri-Rolla, Rutgers University, and Western Michigan University. Its purpose is to understand and measure geophysical changes resulting from microbial interactions with geologic media. Specific objectives of the project are to conduct laboratory and field studies to investigate: (1) the effect of increases in microbial cell concentrations and biofilm formation on soil and sediment electrical properties, (2) the effect of metabolic by-products of microbial activity, such as biosurfactants and organic acids, on geophysical electrical measurements, (3) potential changes in petrophysical properties (e.g., permeability, porosity, surface area) induced by microbial-mineral interactions, and (4) differences in the microbial communities and their structure, dynamics, and associations in sediments with anomalous geophysical signatures. The first phase of the work will involve measuring the electrical signatures of bacterial cells, biofilms, and organic acids in laboratory column reactors. Final reactor products will then be imaged with photomicrography to investigate biofilm distribution and changes in pore geometry. The second phase of the work will focus on measurements of reactor sediment physical properties (formation factor, surface area, porosity, permeability). Results of this work will help build a database to relate electrical, physical, and biochemical parameters that can be used in geophysical modeling of field input data. The final phase of the program will concentrate on field measurements and observations on how changes in sediment electrical conductivity can be related to microbial alteration of geologic materials. These analyses will be carried out on cores and at the field scale. This study will form the basis for the development of geophysics as a tool for investigating geomicrobiological processes. Broader and potential societal benefits include development of geophysical techniques that can be used for monitoring and assessing biological colonization of groundwater aquifers and microbial mineralization of dissolved pollutants in the near subsurface. Educational and outreach initiatives will focus on student involvement and student-led promotion of biogeophysics to the wider Geophysics and Biogeosciences community at national mad international meetings.