Long-Term Fine-Grained Sediment Records in a Drainage System in Arid China: A New Perspective from Paleo-Climatological Records and Simulations

Atmospheric particulate matter (PM 2.5 and PM 10) can adversely affect human health and also has impacts on climate and precipitation. Much research has been done on the transport of human-made fine-grained matter in modern times. It is still unclear, though, what controls the transport process of fine-grained sediment from natural sources on the millennial scale. In this study, we present Holocene basin-wide fine-grained sediment records from the Shiyang River drainage basin system in arid China. Six Holocene sedimentary sequences were collected from various geomorphological units of the drainage system. A total of 1,043 sediment samples were obtained for analysis of fine-grained sediment; fifty-eight radiocarbon dates were acquired for establishing the geochronological frames. In addition, we synthesized the results from transient paleo-climate simulations to understand environmental backgrounds of the Holocene. Our records and simulations indicated that fine-grained sediment 2.5 μm content was relatively stable and less affected by monsoon intensities and circulations. Millennial-scale fine-grained sediment 10 μm content varied according to sedimentary facies, and it was negatively correlated with the winter monsoon intensity at eolian sediments. The fine-grained sediment 10 μm content increases dramatically at lacustrine layers in lake and alluvial sediments from the middle and lower drainage basin, showing its relationship with long-term moisture conditions that are closely related to monsoon precipitation based on climate simulations. This finding contributes to our understanding of the fine-grained matter trends against the backdrop of global warming.