In situ measurements of chemical distributions in a deep-sea hydrothermal vent field.

Large changes in the concentration of sulfide around a hydrothermal vent in the Galápagos Rift provide direct evidence for the consumption of sulfide by the organisms of the vent community. These changes were detected with a new chemical analyzer capable of measuring silicate, sulfide, oxygen, and temperature on the sea floor at depths of 2500 meters. More than 10,000 measurements showed systematic variations in the sulfide and oxygen concentrations due to biogenic oxidation of sulfide in the hydrothermal solutions. Silicate concentration was highly correlated with temperature, but different trends were observed at different locations.