Estimating the Asian radon flux density and its latitudinal gradient in winter using ground-based radon observations at Sado Island     

By ALASTAIR G. WILLIAMS  SCOTT CHAMBERS  WLODEK ZAHOROWSKI  JAGODA CRAWFORD  KIYOSHI MATSUMOTO  MITSUO UEMATSU 《Tellus. Series B, Chemical and physical meteorology》2009,61(5):732-746

Terrestrial radon-222 flux density for the Asian continent, integrated over distances of 4500 km, is estimated in two 20° latitudinal bands centred on 48.8°N and 63.2°N. The evaluation is based on three years of wintertime radon measurements at Sado Island, Japan, together with meteorological and trajectory information. A selection of 18% of observations are suitable for evaluation of an analytical expression for the continental surface flux. Various meteorological assumptions are discussed; it is found that there is a substantial effect of increased complexity of the formulation on the flux estimates obtained. The distribution of spatially integrated radon flux over the Asian landmass is reported for the first time. Expressed as geometric means and 1σ-ranges, estimated fluxes are 14.1 mBq m⁻² s⁻¹ (1σ-range: 18 mBq m⁻² s⁻¹) and 8.4 mBq m⁻² s⁻¹ (1σ-range: 10 mBq m⁻² s⁻¹) for the lower and higher latitude bands. These results constitute an annual minimum in flux densities for these regions, and are higher than previously reported. The existence of a latitudinal gradient in the continental radon source function is confirmed; the present estimate for Asia (−0.39 mBq m⁻² s⁻¹ per degree of latitude) is in agreement with the northern hemisphere terrestrial radon flux gradient proposed previously.  相似文献   

Boron isotope variations in the atmosphere   总被引：2，自引：0，他引：2  

YOSHIKI MIYATA  TAKAYUKI TOKIEDA  HIROSHI AMAKAWA  MITSUO UEMATSU  YOSHIYUKI NOZAKI 《Tellus. Series B, Chemical and physical meteorology》2000,52(4):1057-1065

We report here the first measurements of boron isotope ratios in the maritime atmosphere together with those of precipitation. The δ¹¹B values of atmospheric condensates in the western North Pacific and Japanese coast and snow in Tokyo range from −12.8 to +5.1‰ and from −0.4 to +0.4‰, respectively, which are significantly lower than those of rainwater (+18.9 to +34.7‰) collected mostly over the North Pacific. Since the ¹¹B/¹⁰B ratios of the atmosphere are lower than those of volcanic emissions (δ¹¹B=+2.3 to +21.4‰), we must seek sources for atmospheric boron other than volcanism. We postulate that the sea may be an important supplier for atmospheric boron under some dynamic conditions and that boron isotope fractionation during evaporation from seawater and removal from the atmosphere may account for the large variations of ¹¹B/¹⁰B ratios observed in the atmosphere and precipitation.  相似文献