Sterols are one of the most widely distributed group of organic compounds in the
environment, ranging in geological age from Recent to Cretaceous, and are commonly …

An increased ratio of 12C to 13C, an indicator of the principal carbon-fixing reaction of
photosynthesis, is found in sedimentary organic matter dating back to almost four thousand …

ORGANIC matter preserved in marine sediments provides a molecular record of marine
biological processes1, accounts for approximately 20% of all carbon burial2 and plays a key …

Deep drilling into the marine sea floor has uncovered a vast sedimentary ecosystem of
microbial cells,. Extrapolation of direct counts of stained microbial cells to the total volume of …

Our increasing knowledge of the geochemical processes of present-day sedimentation
conditions provides a basis for evaluating the role of oxic and anoxic sedimentary …

ALTHOUGH methane of bacterial origin is ubiquitous in marine and freshwater sediments,
economic accumulations of bacterial gases occur mainly at depths of several kilometres in …

Studies of a marine algal sapropel from Mangrove Lake, Bermuda, by 13C NMR and stable
carbon isotopic methods show that precursors of aquatic kerogen (insoluble …

Sulphur is a significant component of the organic matter in recent and ancient sediments
and in petroleums1, 2, yet the precise nature of its association and incorporation is poorly …

THE steroid carbon skeleton has been widely used as an indicator of biological origin of the
organic material in ancient sediments1–3 and petroleum4. Sterols, presumed precursors of …

COMPOUND-specific isotope analysis by gas chromatography combined with isotope-ratio
mass spectrometry (GC-IRMS) 1, 2 provides a new tool with which to study the carbon cycle …