Diffusion of oxygen into still sea water

Bucket experiments were conducted to measure the rate of diffusion of oxygen into sea water, stripped of dissolved oxygen to about 1 mg/1, of "homogeneous" salinity of
26-30\permil
and with a "stable" temperature gradient. In five successive tests, the water required about 60 hours, under calm laboratory conditions, to exceed 7 mg/1 at all depths in the bucket. Results of these tests indicated input of oxygen to be much more rapid than expected from molecular diffusion of the Fickian type, giving a diffusion coefficient of
6 \times 10^{-3}
cm
²
sec
^-1
compared to
2 \times 10^{-5}
cm
²
sec
^-1
. It is suggested that evaporation in the thin water layer at the air/ water boundary increases the salinity sufficiently to initiate the transfer of oxygen from the atmosphere into sea water by convective movements, even in the presence of a stable temperature gradient and in the absence of turbulence.