Samples for sulfide
analysis were diluted in a solution containing 1 mM NaOH and 0.1 mM
zinc acetate for sulfide fixation. Dissolved sulfide was analyzed
using a Hach Lange kit LCK-653 (Hach, Germany) which is based on the
reaction of sulfide with dimethyl-p-phenylenediamine
and ferric chloride. The absorption was measured in a spectrophotometer
DR3900 (Hach, Germany). Sulfate was measured by ion chromatography
on a Dionex ICS 2100 equipped with an IonPac AS19 column (4 ×
2550 mm) (Dionex, USA) eluted at 30 °C with potassium hydroxide
(5 mM, 1 mL·min–1).
The headspace composition
of the batch bottles was analyzed with gas chromatography (Shimadzu
GC-2010 series) equipped with two columns in parallel, a Porabond
Q (50 m × 0.53 mm) and Molsieve 5A (25 m × 0.53 mm) for
nitrogen, oxygen, and methane. Hydrogen analysis was carried out with
a Hewlett Packard GC-5890 series equipped with a CP-Molsieve 5A column
(30 m × 0.53 mm). Acetate, propionate, butyrate, methanol, and
ethanol were measured with a GC system Agilent 7890B equipped with
an HP-FFAP column (25 m × 0.32 mm). Formate was analyzed with
an HPLC system Ultimate 3000 (Thermo Fisher, USA) equipped with an
Alltech OA-1000 column (300 mm × 6.5 mm) (Hichrom, UK) eluted
at 60 °C with sulfuric acid (1.25 mM, 0.6 mL·min–1).
analysis were diluted in a solution containing 1 mM NaOH and 0.1 mM
zinc acetate for sulfide fixation. Dissolved sulfide was analyzed
using a Hach Lange kit LCK-653 (Hach, Germany) which is based on the
reaction of sulfide with dimethyl-p-phenylenediamine
and ferric chloride. The absorption was measured in a spectrophotometer
DR3900 (Hach, Germany). Sulfate was measured by ion chromatography
on a Dionex ICS 2100 equipped with an IonPac AS19 column (4 ×
2550 mm) (Dionex, USA) eluted at 30 °C with potassium hydroxide
(5 mM, 1 mL·min–1).
The headspace composition
of the batch bottles was analyzed with gas chromatography (Shimadzu
GC-2010 series) equipped with two columns in parallel, a Porabond
Q (50 m × 0.53 mm) and Molsieve 5A (25 m × 0.53 mm) for
nitrogen, oxygen, and methane. Hydrogen analysis was carried out with
a Hewlett Packard GC-5890 series equipped with a CP-Molsieve 5A column
(30 m × 0.53 mm). Acetate, propionate, butyrate, methanol, and
ethanol were measured with a GC system Agilent 7890B equipped with
an HP-FFAP column (25 m × 0.32 mm). Formate was analyzed with
an HPLC system Ultimate 3000 (Thermo Fisher, USA) equipped with an
Alltech OA-1000 column (300 mm × 6.5 mm) (Hichrom, UK) eluted
at 60 °C with sulfuric acid (1.25 mM, 0.6 mL·min–1).