필리핀해에 운반되는 황사의 기원지와 이동 경로 : 동위원소 및 점토광물 조성 연구

Abstract

Provenance and transport pathways of dust to the tropical-subtropical northwestern Pacific were investigated with clay mineral assemblage and radiogenic isotope (143Nd/144Nd and 87Sr/86Sr) compositions of eolian dust preserved in a deep-sea sediment core (12°30′N, 134°60′E) retrieved from the Palau-Kyushu Ridge in the Philippine Sea. The analytical results revealed the influence of two prevailing dust sources, namely, the Asian deserts and nearby volcanic arcs, with average contribution of ~70% and ~30%, respectively. The clay mineral composition of the core resembled dust from the central Asian deserts (CADs e.g., the Taklimakan Desert) as in the North Central Pacific, but referring to the previously published data, the aerosol collected near the study site during winter/spring has the mineralogical signature of dust originating from the East Asian deserts (EADs). These data indicate that the relative contribution of EAD dust increases with the northeasterly surface winds associated with the East Asian Winter Monsoon (EAWM) during winter/spring, but the Prevailing Westerlies and Trade Winds that carry dust from the CADs is the dominant transport agent in the overall dust budget of the study site. The results of this study contradict the prevailing view that direct dust transport by the EAWM winds in spring dominates the annual flux of eolian dust in the northwest Pacific. sediment core (12°30′N, 134°60′E) retrieved from the Palau-Kyushu Ridge in the Philippine Sea. The analytical results revealed the influence of two prevailing dust sources, namely, the Asian deserts and nearby volcanic arcs, with average contribution of ~70% and ~30%, respectively. The clay mineral composition of the core resembled dust from the central Asian deserts (CADs e.g., the Taklimakan Desert) as in the North Central Pacific, but referring to the previously published data, the aerosol collected near the study site during winter/spring has the mineralogical signature of dust originating from the East Asian deserts (EADs). These data indicate that the relative contribution of EAD dust increases with the northeasterly surface winds associated with the East Asian Winter Monsoon (EAWM) during winter/spring, but the Prevailing Westerlies and Trade Winds that carry dust from the CADs is the dominant transport agent in the overall dust budget of the study site. The results of this study contradict the prevailing view that direct dust transport by the EAWM winds in spring dominates the annual flux of eolian dust in the northwest Pacific.