Remediation is expensive. What if you could “see” the microbial colonies degrading contaminants at your site? You don’t have to rely solely on soil and groundwater sampling to understand the subsurface microbiome. Aestus showcased how the microbiome at contaminated sites can be imaged electrically at the 2025 Battelle Bioremediation Conference, poster featured below.
If National Geographic Imaged Subsurface Biomes
Identifying zones of biodegradation is crucial to site understanding when optimizing a remediation strategy. Because of the variability in microbial growth, however, utilizing monitoring well data alone to identify microbial activity typically results in an incomplete evaluation. Geophysical tools are one of the best ways to evaluate microbial presence between the wells. Aestus’ CTO, Dr. Todd Halihan, presented sites where biogeophysical investigations supported monitored natural attenuation (MNA). The poster session demonstrated how electrical resistivity data can define microbially active zones, rather than relying solely on low density monitoring well data.
During microbial metabolic processes, microbial communities exhibit electroactivity. In turn, the microbes show themselves as electrically conductive areas with complex structures. The presentation showcased real-world electrical images of microbial colonies, such as “root” and “chimney” structures. The electrical resistivity signals also highlighted how the presence or absence of microbially active zones depends strongly on the distribution of contamination, electron acceptors, and available nutrients.
By integrating the images with monitoring well samples to quantify the redox state and presence of electron acceptors, better Conceptual Site Models (CSMs) were developed. In the case studies shown, the updated CSMs led to reduced uncertainty and more defensible performance evaluations.
Learning Lab: Applied Electrical Hydrogeology:
Attendees engaged in a technical discussion in a Learning Lab session; how can environmental professionals leverage electrical imaging to characterize bioactivity at their sites? The session walked through practice datasets illustrating electrical resistivity responses to the water table, bioactivity, NAPL presence, and grain size.
Together, the poster and Learning Lab showed how the subsurface microbiome can be “seen” with electrical resistivity imaging.
