ATMOSPHERIC TRANSPORT OF BOMB-PRODUCED CL-36

Cl-36 measurements have been made in an arctic ice core drilled near the Dye-3 site (65-degrees 11'N, 43-degrees 50'W). The samples analyzed cover the period between 1945 and 1985 with annual resolution. Due to the release of Cl-36 to the atmosphere from nuclear bomb tests, the data shown a peak in the late fifties with Cl-36 fallout rates about three orders of magnitude higher than expected from cosmic ray production. The time resolution is now precise enough to resolve the structure of the descending part of the fallout pattern. From the fallout rates obtained, a stratospheric residence time for bomb-produced Cl-36 could be derived. A detailed interpretation of the data is done with a four-box atmospheric transport model. The large and well-defined Cl-36 bomb pulse provides an excellent tracer for ground water studies.