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Wei N.,University of Illinois at Urbana - Champaign | Wei N.,Institute of Genomic Biology | Finneran K.T.,Clemson University
Biodegradation | Year: 2013

Experiments with trichloroethylene-contaminated aquifer material demonstrated that TCE, cis-DCE, and VC were completely degraded with concurrent Fe(III) or Fe(III) and sulfate reduction when acetate was amended at stoichiometric concentration; competing TEAPs did not inhibit ethene production. Adding 10× more acetate did not increase the rate or extent of TCE reduction, but only increased methane production. Enrichment cultures demonstrated that ~90 μM TCE or ~22 μM VC was degraded primarily to ethene within 20 days with concurrent Fe(III) or Fe(III) + sulfate reduction. The dechlorination rates were comparable between the low and high acetate concentrations (0. 36 vs 0. 34 day-1, respectively), with a slightly slower rate in the 10× acetate amended incubations. Methane accumulated to 13. 5 (±0. 5) μmol/tube in the TCE-degrading incubations with 10× acetate, and only 1. 4 (±0. 1) μmol/tube with low acetate concentration. Methane accumulated to 16 (±1. 5) μmol/tube in VC-degrading enrichment with 10× acetate and 2 (±0. 1) μmol/tube with stoichiometric acetate. The estimated fraction of electrons distributed to methanogenesis increased substantially when excessive acetate was added. Quantitative PCR analysis indicated that 10× acetate did not enhance Dehalococcoides biomass but rather increased the methanogen abundance by nearly one order of magnitude compared to that with stoichiometric acetate. The data suggest that adding low levels of substrate may be equally if not more effective as high concentrations, without producing excessive methane. This has implications for field remediation efforts, in that adding excess electron donor may not benefit the reactions of interest, which in turn will increase treatment costs without direct benefit to the stakeholders. © 2012 Springer Science+Business Media Dordrecht. Source


Miresmailli S.,Energy Bioscience Institute | Miresmailli S.,Sumatics LLC | Nabity P.,Institute of Genomic Biology | Mitchell C.A.,Energy Bioscience Institute | And 9 more authors.
Insect Science | Year: 2013

The extensive land use conversion expected to occur to meet demands for bioenergy feedstock production will likely have widespread impacts on agroecosystem biodiversity and ecosystem services, including carbon sequestration. Although arthropod detritivores are known to contribute to litter decomposition and thus energy flow and nutrient cycling in many plant communities, their importance in bioenergy feedstock communities has not yet been assessed. We undertook an experimental study quantifying rates of litter mass loss and nutrient cycling in the presence and absence of these organisms in three bioenergy feedstock crops-miscanthus (Miscanthus x giganteus), switchgrass (Panicum virgatum), and a planted prairie community. Overall arthropod abundance and litter decomposition rates were similar in all three communities. Despite effective reduction of arthropods in experimental plots via insecticide application, litter decomposition rates, inorganic nitrogen leaching, and carbon-nitrogen ratios did not differ significantly between control (with arthropods) and treatment (without arthropods) plots in any of the three community types. Our findings suggest that changes in arthropod faunal composition associated with widespread adoption of bioenergy feedstock crops may not be associated with profoundly altered arthropod-mediated litter decomposition and nutrient release. © 2012 Institute of Zoology, Chinese Academy of Sciences. Source

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