Aerobic Acetate Degradation near the Capillary Fringe of Roadside Soil: Field Simulations from Soil Microcosms
1995
Ostendorf, D. W. | DeGroot, D. J. | Pollock, S. J. | Gagnon, P. J.
We studied the aerobic degradation of acetate in a roadside soil to assess the reduction of O₂ demand imposed by an alternative highway deicing agent on groundwater. Aseptic uniform sand samples adjacent to the capillary fringe of a state highway shoulder in southeastern Massachusetts were placed in sterile serum bottles at 5°C, forming a series of aerobic soil microcosms. The samples were dosed with a reagent-grade glacial acetic acid solution, then sampled at various time intervals and analyzed by ion chromatography in a laboratory determination of the microbial degradation kinetics. The aerobic reaction rates were slower than those observed in loamy sand near the ground surface in an earlier study. A steady state transport model for the alternative highway deicing agent calcium magnesium acetate [CMA; Ca₀.₃ Mg₀.₇(C₂H₃O₂)₂] was derived, including infiltration and degradation. Simulations were run using the observed microcosm kinetics for a range of assumed snowmelt rates. The resulting profiles suggest that microbial activity within the uniform sand near the capillary fringe has the potential to reduce O₂ demand by CMA on groundwater for slow (<5×10⁻⁷ m/s) snowmelt rates at 5°C under aerobic conditions. More rapid infiltration passes more CMA to the underlying aquifer.
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