Speaker
Description
Microbial activity transforms subsurface environments into living porous media whose physical and chemical properties evolve dynamically in space and time. Through growth and biofilm formation, microbes clog pores, redistribute flow paths, and modify permeability, thereby reshaping fluid flow, solute transport, and redox conditions. Yet, these coupled processes remain highly uncertain, particularly with respect to biofilm hydraylic properties and their interaction with their surrounding physicochemical environment. Improving predictions of contaminant fate, nutrient cycling, and greenhouse gas emissions therefore requires a clearer understanding of microbially mediated transport processes at the pore scale.
Here, we examine how biofilm properties regulate flow distribution, solute transport, and oxygen dynamics in porous media from two complementary perspectives. First, we quantify the sensitivity of flow channelization and solute elution to effective biofilm permeability and porosity reduction. Second, we investigate how the balance between oxygen delivery and microbial consumption within biofilms gives rise to the formation of anoxic microzones implicated in greenhouse gas production in riverbed sediments.
We perform pore-scale direct numerical simulations of flow and transport based on high-resolution microscopy images of biofilm development in soil-on-a-chip microfluidic reactors. Conservative and reactive transport simulations are used to evaluate residence times and microbial reaction rates across systematically varied P´eclet, Damk¨ohler numbers, biofilm permeabilities, and biomass fractions. Results show that flow redistribution and late-time solute tailing are more sensitive to biofilm permeability than total biomass volume, that anoxic microzones emerge under transport-limited conditions, and that three characteristic oxygenation regimes arise along streamtubes.
By linking biofilm permeability to flow reorganization, transport limitation, and oxygen delivery, this work clarifies when and where bioclogging fundamentally alters solute retention and redox structure in porous media, with implications for contaminant persistence, nutrient cycling, and greenhouse gas production in the subsurface.
| Country | United States |
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