Hardness was calculated as CaCO3 equivalent based on calcium and magnesium concentrations. Analysis of anions (NO3−, NO2−, SO42−, Cl−, HCO3−/CO32−) was performed on a Dionex

ICS-2000 Ion Chromatograph with IonPac AS-18 analytical column, 25 μL sample loop, and 21 mM KOH eluent. Due to the high pH of the mobile phase, carbonate species were analyzed as CO32−. AUY-922 solubility dmso Since the speciation cannot be resolved with this method, results are represented as ‘HCO3− + CO32−’. Bromide data were not available due to interference from the end of the carbonate peak, which occurred with this chromatographic method. This issue was unable to be resolved at the time of analysis. Carbonate data were considered usable based on consistently HCS assay good calibration curves (R2 > 0.98) using peak height rather than peak area to deal with the interference with the bromide peak. The unfiltered remainder from the amber collection bottle was analyzed within seven days for specific conductance and total suspended solids (TSS). Specific conductance was measured using a Fisher Scientific bench-top meter. TSS was determined by filtering 450 mL of sample through standard 934-AH glass fiber filters and determining the difference

of oven-dry mass before and after filtration. Water samples for dissolved gas extraction were stored at 4 °C until analysis, which occurred within two days of original sampling. The initial step was to remove a subsample of water to allow for sampling of headspace gas according to the phase equilibration technique (Davidson and Firestone,

1988 and Kampbell and Vandegrift, 1998). In order to be able to remove water from the full glass sampling bottle without contacting ambient air, a Tedlar bag filled with high purity helium was attached to tubing and a 21 gauge syringe needle, and the needle was inserted in the bottle stopper. A syringe was then Protein tyrosine phosphatase inserted in the stopper and 20 mL of water sample was removed. The 20 mL water sample was injected into a pre-evacuated 125 mL serum bottle capped with a rubber septum. The headspace in this bottle was filled with high purity helium to equalize the internal pressure. The bottles were kept at 4 °C for 24 h, at which point they were removed and shaken vigorously for ten seconds to ensure gas equilibration. A gas sample was then removed from the headspace via syringe and injected into a pre-evacuated 12 mL Labco Exetainer. Gas samples were then sent to the UC Davis Stable Isotope Laboratory for analysis of methane concentration and δ13C-CH4 using a Thermo Scientific GasBench-PreCon trace gas system interfaced to a Delta V Plus IRMS (Isotope Ratio Mass Spectrometer).