TABLE 2.

First-order rate coefficients k, stoichiometric ratios for SO₄²⁻ reduction concomitant with the degradation of carbon sources, and isotope enrichment factors during microbial SO₄²⁻ reduction in four PPTs

Test	First-order rate coefficient k ± SD (day−1)		Stoichiometric ratiosa			Isotope enrichment factor ɛ ± SD (‰)
	SO42−	Carbon source	Actual ± SD	Theoretical
				Completeb	Incompletec
PPTpr	0.29 ± 0.02	0.19 ± 0.02	1.51 ± 0.25	0.57	1.33	20.2 ± 1.2
PPTbu	0.19 ± 0.01	0.14 ± 0.01	1.63 ± 0.25	0.40	0.66	25.7 ± 1.8
PPTla	0.32 ± 0.03	0.13 ± 0.01	0.97 ± 0.15	0.66	2.00	16.1 ± 0.8
PPTac	0.24 ± 0.01	0.60 ± 0.06	3.49 ± 0.51	1.00	—	20.8 ± 1.2

^aExpressed as moles of carbon source utilized per mole of SO₄²⁻.

^bComplete, complete oxidation to CO₂.

^cIncomplete, incomplete oxidation to acetate.