Biogeophysics of Bacterial-Mineral Interactions in Surface and Groundwater Systems

拟议的研究计划的目标是发展对水系统中水流对物理和生物地球化学特性以及复合细菌-矿物聚集体的影响的定量理解。具体来说，研究将集中在水动力剪切致密化（即孔隙弹性变形）如何影响微生物活动、细菌-矿物集合体结构、尺寸、孔隙度、渗透率、容重和沉降行为。这些不同物质特性和环境质量运输之间的复杂相互作用也为地球物理调查提供了科学背景，利用探地雷达和电阻率层析成像技术，通过校准地球物理测量，直接测量细菌矿物聚集体的生物地球物理材料特性，来探测和成像环境中的细菌矿物相互作用。这种见解对于解决物理、化学、生物和水文过程之间复杂的相互作用具有根本的相关性，这些过程调节养分循环、污染物运输和水质，以及地下和地表水库之间的水交换。利用生物地球物理材料属性的直接测量来校准间接地球物理估计，还提供了许多潜在的新应用，范围从研究更大范围内细菌-矿物相互作用的特征空间变异性，以及监测生物地球化学对持续的自然和人为环境变化的响应，到探索极端环境中的生命（例如，深层地下生物圈，其他行星）。

The objective of the proposed research program is to develop a quantitative understanding of the influence of water flow on the physical and biogeochemical properties and of composite bacterial-mineral aggregates in aqueous systems. Specifically, studies will focus on how hydrodynamic shear densification (i.e., poroelastic deformation) influences microbial activity, bacterial-mineral aggregate structure, size, porosity, permeability, bulk density, and settling behavior. The complex interplay between these various material properties and environmental mass transport also provide scientific context for geophysical investigations using ground penetrating radar and electrical resistivity tomography to detect and image bacterial-mineral interactions in the environment by calibration of geophysical measurements with direct measurements of biogeophysical material properties of bacterial-mineral aggregates. Such insight is of fundamental relevance to addressing the complex interactions between physical, chemical, biological and hydrological processes that regulate nutrient cycling, contaminant transport and water quality, and the exchange of water between subsurface and surface reservoirs. The use of direct measurements of biogeophysical material properties to calibrate indirect geophysical estimates additionally offers numerous potential new applications that range from investigations on the characteristic spatial variability of bacterial-mineral interactions over larger areas, as well as monitoring biogeochemical responses to ongoing natural and anthropogenic environmental change, to exploration of life in extreme environments (e.g., deep subsurface biosphere, other planets).