Measurement of the diffusion coefficients of sparingly soluble gases in water

The diffusion coefficients D of important gas tracers dissolved in water and seawater were measured with a modified Barrer method. The measurements include the gases He, Ne, Kr, Xe, H2, CH4, and CO2 dissolved in distilled water in the temperature range from 5 to 35°C, and He and H2 dissolved in seawater in the same temperature range. The maximum systematic error is estimated to be well below 5%. The isotopic fractionation in the diffusion coefficient was determined to be (0.87 ± 0.05) for 13CO2/12CO2 and (15 ± 3)% for 3He/4He.