Biogeophysics of Bacterial-Mineral Interactions in Surface and Groundwater Systems

拟议的研究计划的目的是定量了解水流对水系统中的物理和生物地球化学性质以及复合细菌-矿物聚集体的影响。具体地说，研究将集中在流体剪切致密化(即孔洞弹性变形)如何影响微生物活动、细菌-矿物集合体结构、大小、孔隙率、渗透性、体积密度和沉降行为。这些不同的物质性质与环境质量传输之间的复杂相互作用也为地球物理调查提供了科学依据，使用探地雷达和电阻率层析成像技术探测和成像环境中的细菌-矿物相互作用，方法是将地球物理测量与直接测量细菌-矿物集合体的生物地球物理材料性质进行校准。这种见解对于处理物理、化学、生物和水文过程之间的复杂相互作用具有根本意义，这些过程调节营养循环、污染物迁移和水质，以及地下和地表水库之间的水交换。此外，利用生物地球物理材料性质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用途，从调查较大区域细菌-矿物相互作用的特征空间变异性，以及监测对持续的自然和人为环境变化的生物地球化学反应，到探索极端环境(例如，深层地下生物圈、其他行星)中的生命。

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).