干旱区生态环境知识资源中心

Asian dust and volcanogenic materials are two major components in the northwestern Pacific. Quantitatively distinguishing them and estimating their mass accumulation rates (MARs) are very important for understanding regional and global climate change. Here we present the grain-size composition of detrital sediments and the radiogenic strontium (Sr) and neodymium (Nd) isotopic compositions of different grain-size fractions of detrital sediments that were recovered from the western Philippine Sea. These new records show that the different grain-size distributions can be associated with 1) Asian dust from the western and central Chinese deserts and Chinese loess and 2) volcanogenic materials that were derived from the Luzon Islands. The MARs of this Asian dust and volcanic materials are obtained by using Weibull-function fitting. The MARs of Asian dust and volcanic materials are coupled with the glacial-interglacial cycle; these values are found to have been higher and more variable during the glacial period than during the interglacial period. We argue that the strengthening aridity of the Asian continent, which is connected to solar insolation and ice volume variations from orbital eccentricity, constitutes an important mechanism that drives the high MARs of glacial dust in the western Philippine Sea. The internal positive feedback of dust may be another important mechanism. The significant increase in volcanic material during the glacial period was caused by sea level changes, which were driven by the ice volume and solar insolation at high latitudes, and by strengthened precipitation from the El Nino/Southern Oscillation (ENSO), which is driven by orbital eccentricity and precession cycles on the Luzon Islands.