Transient Microsite Models of Denitrification: I. Model Development

Abstract

Abstract Past models of denitrification are reviewed. None of these models include a description of anaerobic volume and transient solute diffusion to and away from zones of N reduction. In this paper, models describing denitrification in the anaerobic zone of a saturated homogeneous soil are presented. The models consider the reduction sequence: nitrate (NO − 3 ) → nitrite (NO − 2 ) → nitrous oxide (N 2 O) → dinitrogen (N 2 ). Anaerobic volume was described by an approximate solution to a moving boundary problem. Transient diffusion of NO − 3 , NO − 2 , N 2 O, and N 2 was allowed throughout the saturated soil, while reduction of the nitrogenous species occurred only in the anaerobic region. Four types of reaction terms were considered, resulting in a zero‐order model, a Michaelis‐Menten model with differential rates of reduction, a Michaelis‐Menten model with NO − 3 and NO − 2 inhibition of N 2 O reduction, and a competitive inhibition model. The use of an operational V max which reflects electron donor availability was proposed.