Host: Abstracts of Annual Meeting of the Geochemical Society of Japan
We analyzed Rb-Sr-Nd isotope ratios of mineral dust in total aerosol load collected with rainwater continuously since 1998 at the summit of Mt. Sefuri, northern Kyushu, southwestern Japan. 87Sr/86Sr in atmospheric mineral dust varied from 0.7096 to 0.7180, and epsilon-Nd(0)CHUR from -19.9 to -3.5. During heavy deposition periods, the dust had high 87Sr/86Sr isotope ratios and low to middle epsilon-Nd(0)CHUR values, respectively. These compositions are comparable to those of sand and loess in arid areas of Northeast China, Takla Makan and Western Beijing. In summer and autumn, the isotopic compositions of the dust varied greatly; however, during light deposition periods, the Sr isotope composition was low. In these seasons, the contributions to the dust from Japanese soils and volcanic ash, transported by southern winds, were relatively larger than in winter and spring because of decreased mineral dust particle transport from the continent. Nevertheless, fine sandy desert particles and loess in general accounted for most mineral dust deposition in northern Kyushu year-round, even in summer.
