Table 1 Calculated fractions of ancient and modern C–sourced CH4 in each sample.
StationWater depth
(m)
Distance
offshore (km)
Sample typeAncient C–sourced
CH4 fraction, fs
Atmospheric-sourced
CH4 fraction, fa
In situ produced
CH4 fraction, fi
123Lagoon0.18 ± 0.060.47 ± 0.180.35 ± 0.25
232Lagoon0.50 ± 0.040.23 ± 0.120.27 ± 0.17
31412Surface0.26 ± 0.060.37 ± 0.180.37 ± 0.24
Near-seafloor0.60 ± 0.040.18 ± 0.100.22 ± 0.13
41510Surface0.39 ± 0.050.29 ± 0.150.33 ± 0.20
Near-seafloor0.45 ± 0.050.25 ± 0.140.30 ± 0.18
51318Surface0.42 ± 0.050.27 ± 0.140.31 ± 0.19
Near-seafloor0.58 ± 0.040.19 ± 0.100.23 ± 0.14
61927Surface0.53 ± 0.040.21 ± 0.120.26 ± 0.16
Near-seafloor0.83 ± 0.020.07 ± 0.040.10 ± 0.06
72848Surface0.10 ± 0.030.72 ± 0.100.18 ± 0.13
Near-seafloor0.86 ± 0.020.06 ± 0.040.08 ± 0.05
83869Surface0.07 ± 0.030.79 ± 0.070.14 ± 0.10
Near-seafloor0.61 ± 0.030.17 ± 0.100.22 ± 0.13