title: NMR measurement of hydrodynamic dispersion in porous media subject to biofilm mediated precipitation reactions.
abstract: Noninvasive measurements of hydrodynamic dispersion by nuclear magnetic resonance (NMR) are made in a model porous system before and after a biologically mediated precipitation reaction. Traditional magnetic resonance imaging (MRI) was unable to detect the small scale changes in pore structure visualized during light microscopy analysis after destructive sampling of the porous medium. However, pulse gradient spin echo nuclear magnetic resonance (PGSE NMR) measurements clearly indicated a change in hydrodynamics including increased pore scale mixing. These changes were detected through time-dependent measurement of the propagator by PGSE NMR. The dynamics indicate an increased pore scale mixing which alters the preasymptotic approach to asymptotic Gaussian dynamics governed by the advection diffusion equation. The methods described here can be used in the future to directly measure the transport of solutes in biomineral-affected porous media and contribute towards reactive transport models, which take into account the influence of pore scale changes in hydrodynamics.
authors.affiliation: Department of Chemical and Biological Engineering, Montana State University, Bozeman MT 59717-3920, USA.
authors.forename: Einar O
authors.initials: EO
authors.lastname: Fridjonsson
authors.forename: Joseph D
authors.initials: JD
authors.lastname: Seymour
authors.forename: Logan N
authors.initials: LN
authors.lastname: Schultz
authors.forename: Robin
authors.initials: R
authors.lastname: Gerlach
authors.forename: Alfred B
authors.initials: AB
authors.lastname: Cunningham
authors.forename: Sarah L
authors.initials: SL
authors.lastname: Codd
mesh_terms: D018407:Bacterial Physiological Phenomena; D018441:Biofilms; D011232:Chemical Precipitation; D004058:Diffusion; D057446:Hydrodynamics; D008279:Magnetic Resonance Imaging; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D016011:Normal Distribution; D016062:Porosity; D012989:Soil Pollutants / Q000032:analysis*; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D012989:Soil Pollutants; D014874:Water Pollutants, Chemical