Description:
<jats:title>Abstract</jats:title><jats:p>This research addresses the challenges of the lack of non‐invasive methods and poor spatiotemporal resolution associated with monitoring biogeochemical activity central to bioremediation of subsurface contaminants. Remediation efforts often include growth of biofilm to contain or degrade chemical contaminants, such as nitrates, hydrocarbons, heavy metals, and some chlorinated solvents. Previous research indicates that nuclear magnetic resonance (<jats:styled-content style="fixed-case">NMR</jats:styled-content>) is sensitive to the biogeochemical processes of biofilm accumulation. The current research focuses on developing methods to use low‐cost <jats:styled-content style="fixed-case">NMR</jats:styled-content> technology to support in situ monitoring of biofilm growth and geochemical remediation processes in the subsurface. Biofilm was grown in a lab‐scale radial flow bioreactor designed to model the near wellbore subsurface environment. The Vista Clara Javelin <jats:styled-content style="fixed-case">NMR</jats:styled-content> logging device, a slim down‐the‐borehole probe, collected <jats:styled-content style="fixed-case">NMR</jats:styled-content> measurements over the course of eight days while biofilm was cultivated in the sand‐packed reactor. Measured <jats:styled-content style="fixed-case">NMR</jats:styled-content> mean log <jats:styled-content style="fixed-case">T<jats:sub>2</jats:sub></jats:styled-content> relaxation times decreased from approximately 710 to 389 ms, indicating that the pore environment and bulk fluid properties were changing due to biofilm growth. Destructive sampling employing drop plate microbial population analysis and scanning electron and stereoscopic microscopy confirmed biofilm formation. Our findings demonstrate that the <jats:styled-content style="fixed-case">NMR</jats:styled-content> logging tool can detect small to moderate changes in <jats:styled-content style="fixed-case">T<jats:sub>2</jats:sub></jats:styled-content> distribution associated with environmentally relevant quantities of biofilm in quartz sand.</jats:p>