Skip to main content
. 2006 Sep 21;103(40):14684–14689. doi: 10.1073/pnas.0606535103

Fig. 3.

Fig. 3.

Carbon-isotopic compositions of methane (δ1, red symbols), ethane (δ2, blue), and propane (δ3, green) at ODP Sites 1226 (open circles), 1228 (open squares), 1229 (diamonds), 1230 (triangles), and 1231 (filled circles) [δn ≡ (13Rn/13Rvpdb) − 1, where 13R ≡ 13C/12C and vpdb designates the Vienna PeeDee Belemnite isotopic standard. Reported values of δ are customarily multiplied by 1,000 and expressed in permil units (‰).] Note that δ1 reflects the isotopic compositions of mixtures of sorbed and dissolved methane with variable relative proportions (e.g., Site 1226, CH4,aq. < CH4,sol.; Site 1228: CH4,aq. < CH4,sol.; Site 1229: CH4,aq. ≈ CH4,sol.; Site 1230: CH4,aq. > CH4,sol.; Site 1231: CH4,aq. ≪ CH4,sol.), whereas δ2 and δ3 largely pertain to the sorbed fraction of the respective gases.