Table 1

Carbon isotopic compositions (versus PDB) and source assignments of selected extracted archaeal ether lipids and bacterial fatty acids (FAs). SRB, sulfate-reducing bacteria.

CompoundEel River Basin, 3 to 5 cmSanta Barbara hydrocarbon seep
δ13C (‰)Source assignmentδ13C (‰)Source assignment
Archaeol−104.1ANME-2Traces/not analyzedArchaea
sn-2-Hydroxyarchaeol−107.6ANME-2Traces/not analyzedArchaea
n-C14:0FA−69.1SRB−22.7Algae, bacteria
i-C15:0FA−51.3SRB, other bacteria−25.4Bacteria mainly
ai-C15:0FA−51.9SRB, other bacteria−19.0Bacteria mainly
n-C16:1(ω7)FA*−62.8SRB−26.0Algae, bacteria
n-C16:1(ω5)FA*−76.1SRB−21.2Algae, bacteria
n-C16:0FA−44.1SRB, other bacteria, algae−20.3Algae, bacteria
10-Me-C16:0FA−69.4SRBNot present
  • * Double-bond positions were determined from nearby samples with almost congruent fatty acid distributions (24) and refer only to the sample from the Eel River Basin.