The Gompertz Function Can Coherently Describe Microbial Mineralization of Growth-Sustaining Pesticides

Anders R. Johnsen, Philip John Binning, Jens Aamand, Nora Badawi, Annette E. Rosenbom

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Mineralization of 14C-labeled tracers is a common way of studying the environmental fate of xenobiotics, but it can be difficult to extract relevant kinetic parameters from such experiments since complex kinetic functions or several kinetic functions may be needed to adequately describe large data sets. In this study, we suggest using a two-parameter, sigmoid Gompertz function for parametrizing mineralization curves. The function was applied to a data set of 252 normalized mineralization curves that represented the potential for degradation of the herbicide MCPA in three horizons of an agricultural soil. The Gompertz function fitted most of the normalized curves, and trends in the data set could be visualized by a scatter plot of the two Gompertz parameters (rate constant and time delay). For agricultural topsoil, we also tested the effect of the MCPA concentration on the mineralization kinetics. Reduced initial concentrations lead to shortened lag-phases, probably due to reduced need for bacterial growth. The effect of substrate concentration could be predicted by simply changing the time delay of the Gompertz curves. This delay could to some extent also simulate concentration effects for 2,4-D mineralization in agricultural soil and aquifer sediment and 2,6-dichlorobenzamide mineralization in single-species, mineral medium.
Original languageEnglish
JournalEnvironmental Science & Technology (Washington)
Volume47
Issue number15
Pages (from-to)8508-8514
ISSN0013-936X
DOIs
Publication statusPublished - 2013

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