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

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

Work site Sample index number °dec N °dec W H2 measured in the field (ppm) GC measurements
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
  1. 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
  2. SAT saturation (overload) of the detector, °dec coordinates in decimal degrees