Table 1.
Analyses of gas trapped by biofilm (Bubbles 1 and 2, see Fig. 1A and B): gas trapped by biofilm on Mn deposit (Bubble 3, see Fig. 1C), immature biofilm bubble, and (Bubble 4, see Fig. 1C) mature biofilm bubble. (N2O, Ethane, Ethene, Ethyne, Propane, Propene, Propyne were also measured but only present in traces).
| Gas (ppm) | Tunnel air | Bubble 1 | Bubble 2 | Bubble 3 | Bubble 4 |
|---|---|---|---|---|---|
| H2 | <3.00 | <3.00 | <3.00 | <3.00 | <3.00 |
| O2 | 173000 | 168000 | 176000 | 175000 | 174000 |
| O2 + Ara | 183000 | 177000 | 183000 | 189000 | 185000 |
| N2 | 783000 | 788000 | 791000 | 781000 | 792000 |
| CO | <20.00 | <20.00 | <20.00 | <20.00 | <20.00 |
| CO2 | 398 | 563 | 435 | 574 | 496 |
| CH4 | 13.6 | 10.8 | 12.0 | 13.0 | 19.9 |
a
High oxygen levels make it difficult to separate oxygen from argon. Therefore oxygen is also reported as argon + oxygen as a combined peak. The remaining gas, to receive 100% analysed gas, could be helium that was not analysed.