Methane Oxidation

Methane oxidation rate from a soil layer, , consists of two parts, CCH4ox1 and CCH4ox2.

                                                  (6.80)

The first term represents oxidation by methanotrophic bacteria at the aerobic interface between the water (or air) and the soil, and is defined as a first order function of the soil methane content and regulated by the Michaelis–Menten kinetics (Bender, 1992):

                                      (6.81)

where  is the methane concentration in soil water, CCH4 is the soil methane content, ko_rate (CH4 AerobicOxRate)is the maximum reaction rate and Ko_50  (CH4 HalfRateOxConstant) is the half rate Michaelis constant.

The second term, , describes the oxidation of methane by plant-transported oxygen which is calculated as a function of the plant root respiration:

                                              (6.82)

where kpox  (CH4 PlantOxidationRate) is a scaling parameter.

The response function is defined as:

                                            (6.83)

where Crootresp is the total carbon emitted by roots, and poxshape is a shape paramater.

In the WMEM model (wetland methane emission model) of Cao, Marshall and Gregson (1996) oxidation is calculated as a single term. An empirical equation is introduced and the oxidation rate is thought to depend just from the maximum gross primary production occurring any month.