Natural and anthropogenic sources of East Asian dust

Nd-Sr isotopic signatures of loess, modern dust, and their potential source materials are systematically investigated to discriminate the natural and anthropogenic sources of eastern Asian dust. Chinese loess is an eolian deposit that has accumulated over the past few million years, and is characterized by a negative Nd-Sr isotopic correlation that implies binary sources for the natural background of eastern Asian dust. Loess in northeastern China shows the highest ε(0) value, while loess in western China has the lowest ε(0). Considering the Nd-Sr isotopic signatures of the potential sources, we propose that the high ε(0) end member is derived from the arid lands around the northern boundary of China while the low ε(0) end member originates from the deserts on the northern margin of the Tibetan Plateau. Chinese Loess Plateau deposits are dominated by northern margin Tibetan Plateau dust, suggesting a strong link between the thick eolian deposit in this region and the evolution of the Tibetan Plateau. The long-range transported spring dust in both Nanjing (south China) and Japan has an Nd-Sr isotopic composition similar to that of loess. However, spring dust in Beijing (north China) has a much lower ε(0) value, indicating an additional anthropogenic contribution of low ε(0) material, possibly from the sandy lands in the adjacent north and west.