Fractionation of Stable Carbon Isotopes during Chemoautotrophic Growth of Sulfur-Oxidizing Bacteria.

Laboratory-grown strains of chemoautotrophic Thiomicrospira sp. strain L-12 and Thiobacillus neapolitanus produced cell carbon that was 24.6 to 25.1 ppt (24.6 to 25.1 mg/g) lower in C isotope abundance than the ambient source of carbon dioxide and bicarbonate. This degree of C isotope depletion was comparable to that found in organic material produced in deep-sea hydrothermal-vent communities.

Biological control of the removal of abiogenic particles from the surface ocean.

Concurrent measurements of particle concentrations in the near-surface water and of particle fluxes in the deep water of the Sargasso Sea show a close coupling between the two for biogenic components. The concentrations of suspended matter appear to follow an annual cycle similar to that of primary production and deepwater particle flux. Although the concentration of particulate aluminum in the surface water appears to vary randomly with respect to that cycle, the removal of aluminum to deep water is intimately linked to the rapid downward transport of organic matter.

Glacial and pluvial periods: their relationship revealed by pleistocene sediments of the red sea and gulf of aden.

Oxygen isotope analyses of planktonic foraminifera from the Red Sea and Gulf of Aden indicate that during periods of maximum continental and polar glaciation in the late Pleistocene, the Red Sea was subject to strong evaporation. Between glacial maximums the salinity of the Red Sea was equal to or below that of the open ocean. This suggests that high-latitude glacial periods corresponded in time to interpluvial stages in the present-day desert belt of northern Africa, whereas high-latitude interglacial periods coincided with pluvial stages.

Methane in lake kivu: new data bearing on its origin.

Lake Kivu, an African rift lake, contains about 50 cubic kilometers of methane (at standard temperature and pressure) in its deep water. Data resulting from two recent expeditions to the lake and a reevaluation of earlier data suggest that most of the methane was formed by bacteria from abiogenetic carbon dioxide and hydrogen, rather than being of volcanic origin or having formed from decomposing organic matter.

Carbon-13 in black sea waters and implications for the origin of hydrogen sulfide.

A combination of measurements of carbon-13 and the hydrogen sulfide content in Black Sea waters with available data on the total carbon dioxide in these waters indicates that the contribution of organic sulfur to the hydrogen sulfide lies between 3 and 5 percent and increases with depth. Likely causes for the increase are increasing productivity or upward movement of the anoxic zone during the facts last 2000 year.