The importance of denitrification as a source of atmospheric N2O, a greenhouse gas, and also an effective removal process of harmful NO3 in aquatic systems has stimulated many researchers into modeling denitrification rates and its products. Modeling denitrification is complicated, as two microbial processes with very contrasting requirements (nitrification and denitrification) have to be considered. The denitrifying population is always present and respiring, but will only denitrify under very specific conditions. Denitrification is therefore a very transient process both in space and time.
For terrestrial systems, simple models calculate denitrification from few essential parameters, for example, NO 3 and carbon content, soil texture, and drainage. More complex models describe the denitrification process in detail, for example, the DNDC model (denitrification decomposition model).
In aquatic systems, denitrification has been calculated from diffusion of substrates and products to and from the active sites for estuaries. For rivers, N removal was calculated from the physical properties of the stream, especially channel size. For marine sediments, a more complex model has been developed that couples the biogeochemical cycling of sedimentary carbon, nitrogen, and oxygen with that in the water column models.
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