Answers are grounded in this paper and cite their sources.
Fundamental data shows oxygen isotope exchange rates and fractionation in sulfate-water systems, implying long equilibration times.
Fundamental data on oxygen isotope behavior in the sulfate-water system are given. Oxygen exchange rates between sulfate ions and water are very slow and show a marked pH dependence. Of the order of 10/sup +3/ to 10/sup +5/ years are required to closely approach isotopic equilibrium at earth surface conditions. Oxygen isotope fractionation experiments yielded the following relationships: Ln alpha = 3878/(t+2) -0.0034 anhydrite water (and) Ln alpha = 3251/(t+2) -0.0056 dissolved sulfate water. During progressive evaporation of saturated CaSO/sub 4/ solution the gypsum formed tends to concentrate oxygen-18 relative to dissolved sulfate by 2%. Sulfate reducing bacteria preferentially metabolize oxygen-16 by about 4.6% in both pure and natural cultures. Oxidation of sulfide to sulfate in natural environments is a complex process making use of both water oxygen and molecular oxygen.
No takes yet. Share an insight, caveat, or question.
R. Michael Lloyd (1968) studied this question.
Synapse has enriched 10 related papers. Consider them for comparative context: