08-09-29 Change of microbial based denitrification model
The previous microbial based model generated instabilities for certain combination of parameter values and time steps. To make the model more robust a new formulation have been made to the internal fluxes of microbial growth and respirations. The model has also been changed to represent a proper definition of the efficiency parameters regulating the partitioning between growh and growth respiration of microbes.
The respiration loss in one pool will form
an input to the next nitrogen pool in the denitrification chain, i.e. the
production of N2, N2O, NO or NO2 (see
Figure 5.0.3). These fluxes (eq. 6.45) were calculated
as:
Are now
replaced by a new equation:
To make sure that the fluxes will not exceed the available amount of the source gas given in the above equations as AnNO3.
The growth respiration for N2O, NO, NO2 and NO3 was before calculated as:
And is now estimated as:
(6.47)
where deffNO3 is an efficiency parameter. Note that the value of the efficiency is now strictly between 0 and 1, a value of .5 implies that half the rate is going to growth and half to respiration. The same value of 0.5 using the previous equation indicated that the respiration loss was twice as big as the growth rate.