Dionex dx 600

In the laboratory, slurries from each site were prepared using previously established procedures (Duddleston et al., 2002 (link); Zhang et al., 2020 (link)) in a glove bag filled with 100% N₂ gas. Excess pore water was squeezed from the peat and woody plant roots and any remaining green vegetation were removed. About 100–300 g peat (wet weight) was homogenized with pore water in a blender at a ratio of ∼1:3 wet weight peat: total volume slurry. Slurries prepared in this manner contained 0.04–0.08 g dried peat per mL. In each of the 200 mL serum bottles, 50 mL of slurries were mixed with 100 mL MilliQ water and incubated for 50 days. On day 1, one set of serum bottle (n = 2) per treatment was amended with 1 mL of 500 mM BES to inhibit methanogenesis (Compeau and Bartha, 1985 (link)). Slurry samples (1.0 mL) for anion analysis were periodically collected from incubation bottles using a plastic 1.0 mL syringe. Samples were centrifuged (12,000 × g) for 5 min and the supernatant filtered through a 0.22 μm sterilized PES syringe filter (Celltreat). Anions (acetate, propionate, butyrate, SO₄^2–, and NO₃^–) were measured by injecting 25 μL of filtered supernatant into an automated Dionex DX600 ion chromatograph (Thermo Scientific) fitted with an AS11HC ion exchange column (4 mm) with suppression and with a potassium hydroxide gradient eluent generator and conductivity detector.