Estimation of the deposition rates of aerosol and sulfur compounds on forest and grassland with cosmic-ray produced radionuclides

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Cosmic-ray produced radionuclides, e.g. ^7Be(the half life:53.3d), ^<32>P(14.3d), ^<33>P(25.3d), and ^<35>S(87.5d), have been produced mainly in upper atmosphere, and immediately bound to aerosol and sulfur compounds in atmosphere. Since their production rates can be estimated based on the strength of cosmic rays, they can trace the behavior of aerosol and sulfur compounds and elucidate the origins, the behavior and the resident times of their compounds. The decay products, ^<210>Pb(22y) and ^<210>Po(138d), of gaseous radioactive radon, ^<220>Rn and ^<220>Rn, are also used for the tracers.Sulfur compounds and above radionuclides have been determined from the samples of aerosol, rainwater, dry deposition and sulfur dioxide collected during each 10 days for one year. They were analyzed by three boxes model (the upper and the lower atmosphere, and the earth surface), and were estimated the transfer rates of aerosol and sulfur compounds upper atmosphere above Fukuoka.The dry deposition rates of aerosol onto various natural and artificial surfaces were measured using by a short half-life radionuclide of ^<212>Pb(10hr). The dry deposition rates of aerosol depend on the roughness (the height of grass or the depth of forest) and the nature of the surface.In order to elucidate the behavior of aerosol in the forest ecology, ^7Be, ^<210>Pb and ^<210>Po have been determined in the samples of stem flow, through fall, and rain water. Furthermore they have analyzed in the fifty parts of one whole tree of Japanese cedar. Their results suggest the behavior of aerosol in the forest ecology.