Artificial river water preparation
Artificial river water was synthesized based on annual average water chemistry of Pump House stream water. Water was dissolved in Milli-Q water and sparged gently with air for 3 days to ensure equilibrium with atmospheric CO2 and O2. pH was adjusted with small amount of HCl/NaOH to achieve final pH of 8.2. After equilibrium, water was filtered through 0.2 μm Corning filter system to remove microbes.
Quantities: 135 mL artificial river water per bottle, pH 8.2, 0.2 μm filtration, major ions: Na+ 72.0 μM, K+ 15.0 μM, Mg2+ 270.0 μM, Ca2+ 1141.0 μM, Cl- 25.0 μM, NO3- 40.0 μM, SO42- 500.0 μM, HCO3- 2100.7 μMDuration: 3 days sparging with airConditions: Atmospheric equilibration, final pH 8.2, sterile conditions after filtration
Equipment: Milli-Q water system, air sparging system, HCl/NaOH, 0.2 μm Corning filter system, polystyrene sterile filter
Batch incubation setup
Batch incubation experiments conducted in duplicate in anaerobic glovebox (~2% H2 and ~98% N2) under ambient temperature (22.5°C). Field-moist sediment samples (15.0 g dry weight equivalent) and artificial river water (135 mL) were mixed in 160-mL serum bottles. Bottles sealed with blue rubber stoppers and aluminum crimp caps, headspace immediately purged with N2 to remove atmospheric O2 and CO2.
Quantities: 15.0 g dry weight equivalent sediment, 135 mL artificial river water, 160-mL serum bottles, duplicate experimentsDuration: 57 days incubation periodConditions: Anaerobic glovebox (~2% H2, ~98% N2), ambient temperature 22.5°C, N2-purged headspace
anaerobic glovebox, 160-mL serum bottles, blue rubber stoppers, aluminum crimp caps, N2 gas