Helium Isotope Effect in Solution in Water and Seawater

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Science  10 Apr 1970:
Vol. 168, Issue 3928, pp. 247-248
DOI: 10.1126/science.168.3928.247


The isotope effect in the solution of helium in water from 0° to 40°C has been determined by microgasometric measurements of the solubilities of pure helium-3 and helium4. At 0°C helium-3 is less soluble than helium-4 in both distilled water and sea-water by 1.2 percent. The observed fractionation factor is 0.988±0.002 at 0°C and appears to decrease with increasing temperature at the rate of 0.0001 per degree Centigrade, although the existence of this trend is of limited statistical certainty. The measured isotope effect is in agreement with the ratio of helium-3 to helium-4 in surface ocean water reported by Clarke, Beg, and Craig.

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