FIG. 6.
Free energy dependence on the substrate and product availability of microbial reactions calculated for typical measured in situ conditions (salinity of 3.11 g/liter, temperature of 17°C, pressure of 10.5 atm, H+ of 10−8 M, H2,aq of 3.8·10−8 M, CH3COO− of 4.3·10−6 M, CH4,aq of 1.5·10−2 M, and HCO3− of 1.7·10−2 M). The data points represent in situ conditions in three, coal gas-producing wells within 5 km of each other. The arrows indicate conditions under which the given reaction is more exergonic than the required minimum (15 or 0 kJ), based on the reactions shown in Table 1.