Estimation of hydrocarbon biodegradation rates in gasoline-contaminated sediment from measured respiration rates

摘要: An open microcosm method for quantifying microbial respiration and estimating biodegradation rates of hydrocarbons in gasoline-contaminated sediment samples has been developed validated. Stainless-steel bioreactors are filled with soil or samples, the vapor-phase composition (concentrations oxygen (O2), nitrogen (N2), carbon dioxide (CO2), selected hydrocarbons) is monitored over time. Replacement gas added as vapor sample taken, selection replacement facilitates real-time decision-making regarding environmental conditions within bioreactor. This capability allows maintenance field time, which not possible closed microcosms. Reaction CO2 O2 calculated from time series. Rates hydrocarbon either measured directly mass balance, estimated reaction assumed stoichiometries. Open experiments using sediments spiked toluene p-xylene were conducted to validate stoichiometric assumptions. Respiration consumption production provide estimates degradation about ±50% values when complete mineralization stoichiometry assumed. Measured ranged 851.1 965.1 g m−3 year−1 toluene, 407.2–942.3 p-xylene. Contaminated a gasoline-spill site used second set experiments. Here, estimate rates. Total 49.0 uncontaminated (background) 1040.4 highly contaminated sediment, based on data. These rate similar those obtained independently situ vertical gradient flux determinations at site. In these experiments, aerobic maintained microcosms by air gas, thus preserving ambient environment subsurface near capillary zone. would be