Evidence for natural molecular hydrogen seepage associated with Carolina bays (surficial, ovoid depressions on the Atlantic Coastal Plain, Province of the USA)

Progress in Earth and Planetary Science

Table 1 Gas chromatography (GC) measurements of soil gas samples

Work site	Sample index number	°dec N	°dec W	H₂ measured in the field (ppm)	GC measurements
Work site	Sample index number	°dec N	°dec W	H₂ measured in the field (ppm)	H₂ (ppm)	O₂ + Ar (%)	N₂ (%)	CH₄ (ppm)	CO₂ (%)	C₂H₆ (ppm)	C₃H₈ (ppm)
Arthur Road Bay		34.7939167	−79.2296667	586	275	20.05	79.30	11	0.62	1	2
Arthur Road Sandpit		34.7869444	−79.2266667	SAT	605	19.37	79.28	735	1.21	1	1
Arthur Road Sandpit, bubbles		34.7870556	−79.2269167	–	0	2.84	35.04	53.57 %	8.56	0	0
Smith Bay	1	34.6824722	−78.5870694	659	179	20.23	79.26	15	0.50	2	2
	2			715	146	20.32	79.15	11	0.51	0	0
	3			574	296	20.38	79.40	17	0.20	2	2
Small new structure inside Jones Lake Bay	1	34.6930278	−78.6004722	210	107	20.12	79.61	194	0.23	0	0
	2	34.6930556	−78.6008056	391	167	16.51	79.35	27468	1.38	0	0
	3	34.6928131	−78.6003308	477	202	20.00	78.11	5875	1.28	0	0
	4	34.6928232	−78.6003460	815	463	18.67	78.66	13783	1.24	0	0
Jones Lake Sandpit	1	34.7001111	−78.5867222	3700^*	698	14.54	84.02	244	1.34	0	0
	2	34.7001111	−78.5872500	719	245	20.34	79.30	15	0.33	0	0
	3	34.7001111	−78.5867222	SAT	1043	14.78	82.12	392	2.96	0	0

Data for all field H₂ measurements were obtained with a GA2000 Plus detector, except in fields marked with *, which were measured with the MDS detector. Total gas measured for each sample is equal to 100 %. Discrepancies between field measurements and laboratory measurements are attributable to the sampling method (see explanation in “Field methods” subsection). Field measurements were usually about twice the laboratory measurements, except where sampling failed. For all field measurements, see Additional file 1: Table SI-1
SAT saturation (overload) of the detector, °dec coordinates in decimal degrees