Bonn 2000 – scientific programme

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MS: Massenspektrometrie

MS 3: Beschleunigermassenspektrometrie

MS 3.6: Talk

Tuesday, April 4, 2000, 15:15–15:30, HS VII

Recirculation of bomb ³⁶Cl — •V. Lazarev¹, A. Blinov², H. Sachsenhauser¹, and E. Nolte¹ — ¹Fakultät für Physik, E15, TU München — ²St.Petersburg State Technical University, Russia

AMS measurements of ³⁶Cl in globally distributed annual precipitation samples have given strong evidence that the experimentally determined deposition fluxes are in average by a factor of about three larger than fluxes calculated from cosmic ray induced atmospheric production. The deviations are most pronounced in tropical regions. These deviations can be explained by storage of part of bomb ³⁶Cl in the biosphere, reentering the troposphere as CH₃Cl, destruction by OH reactions and tropospheric fall-out.

Experiments to collect CH₃Cl from the air and to measure ³⁶Cl/Cl ratios in order to check the hypothesis are presented. Other experiments are performed to measure ³⁶Cl concentrations in lakes with residence times of the lake water between years and thousand years to derive the part of ³⁶Cl deposition fluxes due to recirculation.