HR: 11:10h
AN: B32A-04 INVITED    [Abstracts]
TI: A preliminary study on the transport of biogenic nanoparticles in aquifer environments
AU: * Jin, Q
EM: qjin@uoregon.edu
AF: University of Oregon, 1272 University of Oregon, Eugene, OR 97403, United States
AB: Immobilizing metals and radionuclides as minerals via microbial reduction and precipitation has been proposed as a cost-effective strategy for remediating contaminated aquifers. Biogenic minerals often occur as aggregates of nanoparticles with sizes as small as several to hundreds of nanometers. Because of relatively large chemical reactivity of the nanoparticles, the mobility of biogenic nanoparticles and aggregates are important in evaluating the efficacy and long-term impact of in situ bioremediation. To investigate the mobility of biogenic nanoparticles in aquifer environments, we take iron sulfide produced by pure cultures of sulfate reducing bacteria as an example and characterized the nanoparticles using Fourier transform inferred spectroscopy (FTIR). The FTIR spectra showed that extracellular polymeric substances on the surfaces of the nanoparticles were dominantly proteins and fatty acids. To explore how the surface organic coatings affect the interactions among nanoparticles, we characterized the growth kinetics of biogenic iron sulfide aggregates under various ionic strengths and microbial activities using chemostat reactors and dynamic light scattering. Contrary to the predictions of classical colloid theories, sizes of biogenic aggregates were controlled dominantly by the rates of sulfide production, but not the surface potentials of the nanoparticles. We further quantified the impact of the surface organic coatings on the interactions between the nanoparticle aggregates and aquifer sediments using flow-through column experiments. The experiments under various ionic strengths and aggregate sizes demonstrated that the ionic strength was not significant in controlling the mobility of biogenic aggregates. These preliminary results demonstrated that, because of the organic surface coatings, the production and mobility of biogenic nanoparticle aggregates in aquifers differ significantly from the predictions based on synthesized nanoparticles and colloids. Future experiments are required to elucidate the impact of aquifer hydrogeochemistry on the nature of the surface organic coatings and the mobility of biogenic nanoparticles in aquifers.
DE: 0400 BIOGEOSCIENCES
DE: 0418 Bioremediation
DE: 0419 Biomineralization
DE: 0448 Geomicrobiology
SC: Biogeosciences [B]
MN: 2007 Fall Meeting