Methane Oxidation

Methane oxidation rate from a soil layer, , consists of two parts, C_CH4ox1 and C_CH4ox2.

                                                  (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, C_CH4 is the soil methane content, k_{o_rate} (CH4 AerobicOxRate)is the maximum reaction rate and K_{o_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 k_pox  (CH4 PlantOxidationRate) is a scaling parameter.

The response function is defined as:

                                            (6.83)

where C_rootresp is the total carbon emitted by roots, and p_oxshape 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.