摘要
Deciphering the eolian sources is critical to understand the paleo-significance of the Quaternary eolian deposits(the Xiashu loess)in the lower reaches of the Yangtze River.Both a local source from the fluvial sediments of the Yangtze River and a distal source from the northern deserts similar to that of the loess on the Chinese Loess Plateau(CLP)have been proposed.Recent researches show great advantages of detrital zircon ages as a source tracer for Asian dust based on the laser ablation U-Pb isotopic dating technique.This work presents the U-Pb ages of zircon grains extracted from the Xiashu loess.The results indicate that the Xiashu loess has a very different age distribution of zircon grains from that of the loess on the CLP as well as the materials in the arid lands of the Asian Interior.Instead,the zircon ages of the Xiashu loess are indistinguishable from the fluvial sediments of the Yangtze River,indicating the dominance of proximal dust source.Proximal source of the Xiashu loess implies that extensive eolian processes might have existed in the currently wet South China,possibly in response to the full glacial conditions after the middle Pleistocene transition of global climate.
It is well known that the increases in atmospheric CO2 and CH4 （long-lived greenhouse gases; GHGs） owing to anthropogenic activity are the dominant processes driving global climate change. Space-based measurements of GHGs with high precision, resolution, and global coverage are urgently needed to characterize the geographic distri- bution of their sources and sinks, and to quantify their roles in the atmospheric CO2 budget. Over the past 10 years, the European Space Agency （ESA）, the National Aeronautics and Space Administration （NASA）, and the Japanese Aerospace Exploration Agency （JAXA） have initiated different satellite missions to achieve these goals,
