Isotopic enrichment of heavy ozone in the stratosphere

A mass-independent, 3% enrichment of heavy ozone isotopes in the stratosphere can be assigned to a mechanism in which (1) short-wavelength photodissociation of ozone produces O-2(v greater than or equal to 26) + O, (2) the O-2)(v greater than or equal to 26) reacts with ground state O-2 to produce O-3 + O, and (3) each O atom recombines with O-2 to form O-3. The overall reaction scheme, O-3 + hv + 3O(2) --> 3O(3), produces more ozone than it consumes. The dissociation channel which begins this scheme is more probable for heavy ozone than for O-48(3), and one of the oxygen atoms in the original O-3 is incorporated into a new O-3. Thus this new ozone source tends to ''distill'' heavy oxygen atoms into the O-3 pool while depleting them from the O-2 pool. The amount of enrichment produced by this mechanism, while significant, is still too small to account for the large observed stratospheric enrichment of heavy ozone.