The Natural Distribution of Tritium

The abundance of cosmic-ray-produced tritium has been measured in a variety of natural waters in the Mississippi Valley, the Chicago area, and in a few places elsewhere in the northern hemisphere. Contents ranging between 0.5 and 67 tritium atoms per ${10}^{18}$ hydrogen atoms have been found. These correspond to an average cosmic-ray production rate of about 0.12 tritium atoms per ${\mathrm{cm}}^2$ per second if the total rate of transfer of tritium into the oceans by oceanic rain and snow and by rivers carrying continental water is taken as being equal to the total production rate. This is equivalent to assuming short land storage time in terms of eighteen years—the tritium average life. This production rate corresponds to an inventory of about 1800 g, with only about one percent of this in the atmosphere.