HR: 0800h
AN: H41C-0664    [Abstracts]
TI: Fate of Acrylamide in Soil and Groundwater Systems: Microbial Degradation
AU: * Labahn, S
EM: stephanie.labahn@dri.edu
AF: University of Nevada Las Vegas, 4505 Maryland pkwy., Las Vegas, NV 89154, United States
AU: * Labahn, S
EM: stephanie.labahn@dri.edu
AF: Desert Research Institute, 755 E. Flamingo Rd., Las Vegas, NV 89119, United States
AU: Moser, D
EM: duane.moser@dri.edu
AF: Desert Research Institute, 755 E. Flamingo Rd., Las Vegas, NV 89119, United States
AU: Arrowood, T
EM: arrowoodtodd@yahoo.com
AF: University of Nevada Las Vegas, 4505 Maryland pkwy., Las Vegas, NV 89154, United States
AU: Arrowood, T
EM: arrowoodtodd@yahoo.com
AF: Desert Research Institute, 755 E. Flamingo Rd., Las Vegas, NV 89119, United States
AU: Young, M
EM: michael.young@dri.edu
AF: Desert Research Institute, 755 E. Flamingo Rd., Las Vegas, NV 89119, United States
AU: Robleto, E
EM: eduardo.robleto@unlv.edu
AF: University of Nevada Las Vegas, 4505 Maryland pkwy., Las Vegas, NV 89154, United States
AB: Acrylamide monomer (AMD), a suspected human neurotoxin and carcinogen, is present as a contaminant (up to 0.05%) in commercial preparations of polyacrylamide (PAM). PAM is currently being evaluated for wide-spread use as a temporary water-delivery canal sealant across the western United States. To better constrain potential risks associated with PAM applications, we examined the capacity of natural canal microorganisms to degrade AMD in laboratory and field experiments. Dilution cultivation and enrichment approaches were employed to determine the abundance of culturable microorganisms in several canal habitats which can utilize AMD as a sole nitrogen source (typically 10⁴-10⁶/mL) and a collection of isolates was developed. AMD-degrading microorganisms in our collection fell within a limited diversity of genera including Arthrobacter, Xanthomonas, and Pseudomonas; with the latter demonstrating highest capacity for degrading AMD under laboratory conditions. One strain of Pseudomonas fluorescens, isolated from Klamath Irrigation District (Klamath Falls, OR) canal sediment, was chosen for further study in part because this species is well-studied and ubiquitous. The potential for microbial AMD degradation was tested under laboratory conditions using this strain in repacked short (15 cm) column tests with two relevant soil types (sand and loam). Subsequently, the capacity of mixed natural microbial populations to degrade AMD was examined using soil cores collected from the Highline Canal (Rocky Ford, CO), and canal water/sediment slurries with spiked (5 ppm AMD) in situ bottle tests. Degradation of the monomer in the repacked column experiments was evaluated using a step input of 5 ppm AMD and the canal columns were tested with a range of AMD concentrations (1-5 ppm) followed by quantification with an HPLC. The repacked soil columns inoculated with P. fluorescens demonstrated 80-100% AMD degradation within 12 hours. Natural microbial communities in fresh canal sediment columns produced varying levels of AMD degradation, ranging from 40-50% after 36 hours. The in situ bottle test resulted in 50% degradation after 72 hours. Experimental AMD degradation rates and transport parameters, such as sorption and retardation, were combined to model AMD transport in canal and ground water systems (Arrowood et al. 2007). Initial calculations demonstrate the importance of the microbial role in removal of the monomer and infer possible implications informing the development of safe and effective PAM application protocols.
DE: 0402 Agricultural systems
DE: 0418 Bioremediation
DE: 0448 Geomicrobiology
DE: 0496 Water quality
DE: 1842 Irrigation
SC: Hydrology [H]
MN: 2007 Fall Meeting