Biological formation of ethane and propane in the deep marine subsurface.
Concentrations and isotopic compositions of ethane and propane in cold, deeply buried sediments from the southeastern Pacific are best explained by microbial production of these gases in situ. Reduction of acetate to ethane provides one feasible mechanism. Propane is enriched in (13)C relative to ethane. The amount is consistent with derivation of the third C from inorganic carbon dissolved in sedimentary pore waters. At typical sedimentary conditions, the reactions yield free energy sufficient for growth. Relationships with competing processes are governed mainly by the abundance of H(2). Production of C(2) and C(3) hydrocarbons in this way provides a sink for acetate and hydrogen but upsets the general belief that hydrocarbons larger than methane derive only from thermal degradation of fossil organic material.
Hinrichs
Kai-Uwe
KU
Deutsche Forschungsgemeinschaft-Research Center Ocean Margins, Department of Geosciences, University of Bremen, P.O. Box 330440, 28334 Bremen, Germany. khinrichs@uni-bremen.de
Hayes
John M
JM
Bach
Wolfgang
W
Spivack
Arthur J
AJ
Hmelo
Laura R
LR
Holm
Nils G
NG
Johnson
Carl G
CG
Sylva
Sean P
SP
D002247:Carbon Isotopes; D004980:Ethane / Q000032:analysis*; D019015:Geologic Sediments / Q000737:chemistry; D011407:Propane / Q000032:analysis*; D012623:Seawater / Q000737:chemistry*; D013816:Thermodynamics
D002247:Carbon Isotopes; D004980:Ethane; D011407:Propane