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, H 2 , CH 4 , and CO 2 dissolved in distilled water in the temperature range from 5 to 35°C, and He and H 2 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, ∈ D , was determined to be (−0.87 ± 0.05)‰ for 13 CO 2 / 12 CO 2 and (15 ± 3)% for 3 He/ 4 He.