title: In Situ Detection of Subsurface Biofilm Using Low-Field NMR: A Field Study.
abstract: Subsurface biofilms are central to bioremediation of chemical contaminants in soil and groundwater whereby micro-organisms degrade or sequester environmental pollutants like nitrate, hydrocarbons, chlorinated solvents and heavy metals. Current methods to monitor subsurface biofilm growth in situ are indirect. Previous laboratory research conducted at MSU has indicated that low-field nuclear magnetic resonance (NMR) is sensitive to biofilm growth in porous media, where biofilm contributes a polymer gel-like phase and enhances T2 relaxation. Here we show that a small diameter NMR well logging tool can detect biofilm accumulation in the subsurface using the change in T2 relaxation behavior over time. T2 relaxation distributions were measured over an 18 day experimental period by two NMR probes, operating at approximately 275 kHz and 400 kHz, installed in 10.2 cm wells in an engineered field testing site. The mean log T2 relaxation times were reduced by 62% and 43%, respectively, while biofilm was cultivated in the soil surrounding each well. Biofilm growth was confirmed by bleaching and flushing the wells and observing the NMR signal's return to baseline. This result provides a direct and noninvasive method to spatiotemporally monitor biofilm accumulation in the subsurface.
authors: Center for Biofilm Engineering, Montana State University , Bozeman, Montana 59717, United States.|Department of Chemical and Biological Engineering, Montana State University , Bozeman, Montana 59717, United States.
authors: Catherine M
authors: CM
authors: Kirkland
authors: Chair of Water Chemistry and Water Technology, Karlsruhe Institute of Technology , Karlsruhe 76131, Germany.
authors: Maria P
authors: MP
authors: Herrling
authors: Center for Biofilm Engineering, Montana State University , Bozeman, Montana 59717, United States.
authors: Randy
authors: R
authors: Hiebert
authors: Center for Biofilm Engineering, Montana State University , Bozeman, Montana 59717, United States.|Department of Mechanical and Industrial Engineering, Montana State University , Bozeman, Montana 59717, United States.
authors: Andrew T
authors: AT
authors: Bender
authors: Vista Clara Inc. , 12201 Cyrus Way Ste. 104, Mukilteo, Washington 98275, United States.
authors: Elliot
authors: E
authors: Grunewald
authors: Vista Clara Inc. , 12201 Cyrus Way Ste. 104, Mukilteo, Washington 98275, United States.
authors: David O
authors: DO
authors: Walsh
authors: Center for Biofilm Engineering, Montana State University , Bozeman, Montana 59717, United States.|Department of Mechanical and Industrial Engineering, Montana State University , Bozeman, Montana 59717, United States.
authors: Sarah L
authors: SL
authors: Codd
mesh_terms: D001673:Biodegradation, Environmental; D018441:Biofilms / Q000254:growth & development; D004784:Environmental Monitoring / Q000379:methods*; D060587:Groundwater / Q000382:microbiology*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D016062:Porosity