ISSN:
1365-2389
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Geosciences
,
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
Nitrous oxide contributes to the global greenhouse effect and affects the chemistry of O3 in the upper troposphere and lower stratosphere. To define a relevant model for microbial NO3– and N2O reductions in soil and estimate the parameters involved, we propose a method combining measurements of anaerobic soil slurry and simulations of NO3– and N2O reductions, including non-enzymatic competition between NO3– and N2O as electron acceptors and the microbial dynamics of two denitrifier groups that are either able or unable to reduce N2O. Three models varying in the description of soil capability to reduce N2O through denitrification were assessed. The procedure was applied on an arable soil known for its small N2O emissions in situ during wet events. Experiments consisted of N2O measurements in anoxic conditions (i) with C2H2, (ii) without C2H2 or (iii) without C2H2 and N2O addition, at various NO3– concentrations. The first model that accounts for microbial growth and considers a constant specific N2O reductase activity could not reproduce experimental data. It was necessary to consider that some denitrifiers initially unable to reduce N2O into N2 became able to undertake this process. We evaluated two models taking into account the induction of N2O reductase, either with the progressive synthesis of this reductase simultaneously for all N2O reducers or with the sudden synthesis of this reductase distributed over a range of times for N2O reducers. Both models could approximately describe experimental kinetics, although some biases remained. The biomass of denitrifiers estimated by fitting simulated to experimental data was consistent with the biomass measured using chloroform fumigation–extraction and microbial enumeration.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1365-2389.2004.00681.x
Permalink
