On the 16 O/ 18 O isotope effect associated with photosynthetic O 2 production

Abstract

While photosynthetically evolved O2 has been repeatedly shown to have nearly the same oxygen isotope composition as source water so that there is no corresponding 16O/18O isotope effect, some recent 18O-enrichment studies suggest that a large isotope effect may occur, thus feeding a debate in the literature. Here, the classical theory of isotope effects was applied to show that a very small isotope effect is indeed expected during O2 production. Explanations of the conflicting results are briefly discussed.