title: Kinetics of mineralization of organic compounds at low concentrations in soil.
abstract: The kinetics of mineralization of 14C-labeled phenol and aniline were measured at initial concentrations ranging from 0.32 to 5,000 ng and 0.30 ng to 500 micrograms/g of soil, respectively. Mineralization of phenol at concentrations less than or equal to 32 ng/g of soil and of aniline at all concentrations began immediately, and the curves for the evolution of labeled CO2 were biphasic. The patterns of mineralization of 4.0 ng of 2,4-dichlorophenol per g of soil and 20 ng of nitrilotriacetic acid per g of soil were similar to the patterns for phenol and aniline. The patterns of mineralization of 1.0 to 100 ng of p-nitrophenol and 6.0 ng of benzylamine per g of soil were also biphasic but after a short apparent lag period. The curves of CO2 evolution from higher concentrations of phenol and p-nitrophenol had increasing apparent lag phases and were S-shaped or linear. Cumulative plots of the percentage of substrate converted to CO2 were fit by nonlinear regression to first-order, integrated Monod, logistic, logarithmic, zero-order, three-half-order, and two-compartment models. None of the models of the Monod family provided the curve of best fit to any of the patterns of mineralization. The linear growth form of the three-half-order model provided the best fit for the mineralization of p-nitrophenol, with the exception of the lowest concentrations, and of benzylamine. The two-compartment model provided the best fit for the mineralization of concentrations of phenol below 100 ng/g, of several concentrations of aniline, and of nitrilotriacetic acid. It is concluded that models derived from the Monod equation, including the first-order model, do not adequately describe the kinetics of mineralization of low concentrations of chemicals added to soil.
mesh_terms: D000814:Aniline Compounds / Q000378:metabolism*; D001596:Benzylamines / Q000378:metabolism; D001673:Biodegradation, Environmental; D002733:Chlorophenols / Q000378:metabolism; D008954:Models, Biological; D009571:Nitrilotriacetic Acid / Q000378:metabolism; D009596:Nitrophenols / Q000378:metabolism*; D019800:Phenol; D010636:Phenols / Q000378:metabolism*; D012044:Regression Analysis; D012988:Soil Microbiology
chemical_list: D000814:Aniline Compounds; D001596:Benzylamines; D002733:Chlorophenols; D009596:Nitrophenols; D010636:Phenols; D019800:Phenol; C030796:benzylamine; D009571:Nitrilotriacetic Acid; C004762:2,4-dichlorophenol; C023650:aniline; C024836:4-nitrophenol