Table 1.

Description of Experiment A, B, and C with duplicate bottles for each treatment.

Experiment A	Sediment core collected during August 12th 2013; The goal of the experiment was to determine the effect of different sulfate concentrations on methane production rates, with and without sulfate reduction inhibitor
Treatments	Sulfate concentration in slurry (mM)
	100 μl of 13CH4 (99.999%) was added to all slurries
No inhibitor	9 mM	2 mM	1 mM	Killed control + 9 mM
Sulfate reduction inhibitor	9 mM + Molybdate	2 mM + Molybdate	1 mM + Molybdate
Experiment B	Sediment core collected during October 1st 2013; The goal of the experiment was to determine the effect of inhibitors addition on methane production and effect of sulfate reduction rates and isotopic signature
	10 mM sulfate without substrate addition in all slurries Inhibition conditions
Treatments	No inhibitor addition-control	20 mM BES	10 mM Molybdate
Experiment C	Sediment core collected during October 1st 2013; The goal of the experiment was to determine the effect of substrate and the effect of inhibitors addition on methane production and sulfate reduction rates
Treatment Substrate conditions	10 mM sulfate in all slurries Inhibition conditions
40 mM acetate	No inhibitor	20 mM BES	Molybdate	Killed control with acetate addition
10 mM lactate	No inhibitor