Photosynthesis, the process by which plants utilize the sun's energy to create their own, leaves behind a unique calling card in the form of a chemical signature that is spelled out with stable oxygen isotopes.
Photosynthesis by microscopic plants forms the base of the oceanic food chain, but it is difficult to measure how productive these plants are in natural settings. This research will make it easier to do so.
Most oxygen atoms contain eight protons and eight neutrons and are represented by the symbol O-16. More than 99.9 percent of Earth's oxygen is O-16, but two heavier oxygen isotopes exist in trace amounts: O-17, with one extra neutron, and O-18, with two.