Fig. 3
Experimental setup of the gas flushing experiments. Either air provided by an aquarium pump or O2, N2, CO2 from gas cylinders were pre-wetted by guiding them through a washing flask filled with water prior to flushing. The sediments were poured into Petri dishes and placed without lids in glass chambers with in- and outlet ports for the gases. The glass chambers were kept at 20°C for 3 h and either illuminated with white light of a photon-fluence rate of 200 µmol m−2 s−1 or kept in the dark (not shown in this figure)