Multiple-oxygen isotope constraints on aerobic respiration and gross primary productivity.

Variations in respiratory oxygen isotope fractionation can cause up to 120% error in gross productivity estimates from triple-oxygen-isotope analysis.

• Why it matters: Accurate quantification of Earth's carbon and oxygen fluxes is essential for understanding climate regulation, but current methods like triple-oxygen-isotope analysis rely on assumptions that may not hold true, risking significant inaccuracies.
• What they did: Experiments on Escherichia coli examined how respiratory fractionation varies with cell-specific O2 consumption, dissolved O2, and terminal oxidase type, revealing strong and weak correlations.
• The result: Modeling indicates these factors could lead to substantial errors in marine gross productivity estimates, which might be mitigated by analyzing "clumped" isotopologue abundances in O2.