Investigations of chemical properties and transport mechanisms of continental aerosols are necessary for estimating their influences on global radiative budget and on the global material cycle. Intensive measurements of atmospheric aerosols and the associated species on Rishiri Island, near the northern tip of Japan, were conducted from March to May 2001, in order to understand the chemical properties, source regions, transport pathways, and transport patterns of anthropogenic and mineral aerosols over the east Asian Pacific Rim region during the spring. Mean concentrations of nss‐SO₄²⁻, NO₃⁻, NH₄⁺, nss‐Ca²⁺ in aerosols were 2.48, 0.64, 0.72, and 0.17 μg m⁻³, respectively. Elemental carbon and organic carbon in fine particles (d < 2.5 μm) yielded mean concentrations of 0.25 and 0.80 μg m⁻³, respectively. The concentrations of these species frequently increased to higher values because of outbreaks of continental polluted air masses, whereas under background conditions, they decreased to lower values similar to those observed over the remote ocean. Our results demonstrate that nss‐SO₄²⁻ and NH₄⁺ coexist in fine particles, that NO₃⁻ and nss‐Ca²⁺ coexist in coarse particles, and that each set is transported in an alternate manner. Continentally derived NO₃⁻ is transported as coarse particle to the east Asian Pacific Rim region. Anthropogenic pollutants and dust particles are not necessarily transported together. It was often found that anthropogenic fine particles containing abundant nss‐SO₄²⁻ appeared first and were then followed by large mineral particles that had absorbed NO₃⁻. Short‐term intrusion of the air masses containing abundant particulate carbonaceous compounds, probably due to the influence of biomass burning, also often occurred during the outflow events of continental air masses. Atmospheric behaviors of sulfate, nitrate, and carbonaceous species are different from one another, although they are all derived mainly from combustion processes.

The measurements of atmospheric aerosol and associated species have been carried out on the ground observation network over the western North Pacific as part of the Variability of Marine Aerosol Properties (VMAP) project. The network consists of four Japanese islands (Rishiri, Sado, Hachijo, and Chichi‐jima), ranging widely in latitudes from 25°N to 45°N along with the line of 140°E. In this paper, we report on simultaneous measurements of particulate elemental carbon (EC) on the four islands from March to May 2001, which cooperated with the Asia‐Pacific Regional Aerosol Characterization Experiment (ACE‐Asia) campaign, in order to characterize the outflow patterns of continental polluted air masses to the North Pacific. The mean concentrations of particulate EC in the four islands during this period ranged from 0.18 to 0.60 μg m⁻³. It is interesting to note that the temporal variations in the concentrations of particulate EC in Rishiri and Sado, which are located in the northern region of Japan (35°N–45°N), synchronized with each other. The EC concentrations in Hachijo and Chichi‐jima, located in the southern region of Japan (25°N–35°N), also showed similar temporal variations with each other but did not synchronize with those in Rishiri and Sado. These results demonstrate that the transport patterns of the polluted air masses from the east Asian continent to the northern regions of the northwestern Pacific are often different from those to the southern regions. It was also found that continental air masses are usually accompanied by pollutants over the southern regions but not over the northern regions of the northwestern Pacific.

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. DOI: 10.1111/j.1600-0889.2009.00438.x

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. DOI: 10.1111/j.1600-0889.2009.00438.x