2-Ethyl-3-methylmaleimide in Tokyo Bay sediments providing the first evidence for its formation from chlorophylls in the present photic and oxygenic zone

Tokyo Bay bottom sediments were analyzed for 2-ethyl-3-methylmaleimide, a degradation product of chlorophylls, which has been detected in ancient sediments. It was found in all sediments examined in concentrations of about 1 to 15 nmol/g- of dried sediment, and it was shown to be preserved for 100 years in the sediments. Its depth distribution agreed with that of the reported total organic carbon content of the sediments, reflecting a change in primary productivity. We concluded that this maleimide was produced under photic and oxygenic conditions in nature before the incorporation of photosynthesizing organisms into sediments.

Phenols in hydrothermal petroleums and sediment bitumen from Guaymas Basin, Gulf of California

The aliphatic, aromatic and polar (NSO) fractions of seabed petroleums and sediment bitumen extracts from the Guaymas Basin hydrothermal system have been analyzed by gas chromatography and gas chromatography-mass spectrometry (free and silylated). The oils were collected from the interiors and exteriors of high temperature hydrothermal vents and represent hydrothermal pyrolyzates that have migrated to the seafloor by hydrothermal fluid circulation. The downcore sediments are representative of both thermally unaltered and thermally altered sediments. The survey has revealed the presence of oxygenated compounds in samples with a high degree of thermal maturity. Phenols are one class of oxygenated compounds found in these samples. A group of methyl-, dimethyl- and trimethyl-isoprenoidyl phenols (C27-C29) is present in all of the seabed NSO fractions, with the methyl- and dimethyl-isoprenoidyl phenols occurring as major components, and a trimethyl-isoprenoidyl phenol as a minor component. A homologous series of n-alkylphenols (C13-C33) has also been found in the seabed petroleums. These phenols are most likely derived from the hydrothermal alteration of sedimentary organic matter. The n-alkylphenols are probably synthesized under hydrothermal conditions, but the isoprenoidyl phenols are probably hydrothermal alteration products of natural product precursors. The suites of phenols do not appear to be useful tracers of high temperature hydrothermal processes.