oxygen-18

Kamen used the isotope oxygen-18 to trace the chemical's role in the process, confirming that that the oxygen created during photosynthesis comes only from the water molecules.

Kamen, Martin David 2009

Naturally occurring oxygen-18 (18O) is stable and available commercially, as is water (H2O with 15% 18O).

Oxygen 2007

DMS____________Dimethyl Sulfide, a precursor of various atmospheric sulfur compounds dO18, 'ˆ‚O18_____Change in oxygen-18 isotope level

NOAA Gridded Data « Climate Audit 2007

Other studies used the ratio of oxygen-18 to oxygen-16 δ 18O in the shells, so Mg/Ca provides a parallel measure.

Ars Technica Kyle Niemeyer 2011

In this case, they found a slight excess in the abundance of oxygen-17 and oxygen-18 compared with rocks from Earth, just as we would expect from a Martian rock.

Telegraph.co.uk - Telegraph online, Daily Telegraph and Sunday Telegraph 2011

Using an instrument called a mass spectrometer think of it as an atomic weighing machine, they studied the relative abundance in the meteorite's silicate minerals of three isotopes of oxygen - oxygen-16, oxygen-17 and oxygen-18.

Telegraph.co.uk - Telegraph online, Daily Telegraph and Sunday Telegraph 2011

As a result, as clouds rise they become depleted in oxygen-18.

Scientific American 2010

Because water containing oxygen-18 is heavier than that containing the more common isotope oxygen-16, it falls - and condenses - more easily from clouds.

Scientific American 2010

At issue is the ratio of two stable oxygen isotopes - oxygen-16 and oxygen-18 - in lumps of carbonate mineral found in sediments from dried-out mountain lakes.

Scientific American 2010

As a result, as clouds rise they become depleted in oxygen-18.

Scientific American 2010