|
Governing equations
|
|
Variations of this multiplicative function were used to determine metabolic relationships of the
physicochemical state variables used in this model:
|
|
F = Vmax * f(O2) * f(H2S) * f(PAR) * f(NIR)*f(H)
|
|
where F is the microbial reaction rate, Vmax is the maximum reaction rate , and
f(x) = one of three types of functional relationship (see below)
|
|
|
Ks = the ½ saturation constant; Ki = inhibition constant; Kmax= the
lowest inhibitory value of x; K1/2 = the value at which y=0.5.
|
|
Growth of each bacterial guild occurs as a function of initial biomass multiplied
by the metabolism and a yield factor (see table below).
DIC, sulfide, and O2 move between mat layers (and from the mat surface to
the diffusive boundary layer) based on a diffusion gradient.
PAR was primarily attenuated by the mat, whereas NIR was primarily attenuated
by the water overlying the mat
A three day MBGC simulation using field-measured temperature and light data
from June 4-5, 2001 and October 10-11, 2001 generated DIC,
sulfide,
and O2 results that were compared to June 4-7, 2001,
and October 10-11,2001 field-collected mat data.
|
| |
| Organism |
Metabolism |
Mode1 |
O2 |
H2S |
[H] |
PAR(%) |
NIR(%) |
PAR µmol
quanta |
NIR µmol
quanta |
Yield factors |
Vmax |
| Cyanobacterium (CYA) |
Oxygenic photosynthesis |
Cn |
I |
I |
- |
O |
- |
S |
- |
+8.55g per mol
O2 consumed |
0.0323 h-1 |
| |
Aerobic respiration |
Cn |
S |
- |
- |
- |
- |
- |
- |
-8.55g per mol
O2 produced |
-0.0017 h-1 |
| |
Anoxygenic photosynthesis |
Ind |
- |
O |
- |
O |
- |
S |
- |
+8.55g per mol
H2S consumed |
0.0043 h-1 |
Purple Sulfur
Bacterium (PSB) |
Anoxygenic photosynthesis |
Ind |
- |
O |
- |
- |
O |
- |
S |
+17.1g per mol
H2S consumed |
0.072 h-1 |
| |
Aerobic chemosynthesis |
Cn |
S |
O |
- |
- |
- |
- |
- |
+5.28g per mol
H2S consumed |
0.067 h-1 |
|
|
|
|
|
|
|
|
|
|
+3.94g per mol
O2 consumed |
|
Colorless Sulfur
Bacterium (CSB) |
Aerobic chemosynthesis |
Cn |
S |
S |
- |
- |
- |
- |
- |
+3.0g per mol
H2S consumed |
0.54 h-1 |
|
|
|
|
|
|
|
|
|
|
+1.67g per mol
O2 consumed |
|
Sulfate Reducing
Bacteria (SRB) |
Aerobic(?) chemosynthesis |
Cn |
- |
- |
S |
- |
- |
- |
- |
+1.8g per mol
[H] consumed |
0.004 h-1 |
|
|
1 The metabolism can be constitutive (Cn = always present) or Inductive (Ind = induced by
mechanisms built into the model).
|
|
Table 1. Types of metabolism by the different microbes in the model. The effect
of each physicochemical state variable upon metabolism is modeled using either an inhibition (I),
saturation (S), or optimum curve (O). CYA, PSB, and CSB is from de Wit et
al.1995; SRB values are from Widdle 1988; and from a combination
of published values (Invorsen & Jørgensen 1984; Widdel et al. 1983) and sensitivity testing.
|
