Spatial transport characteristics of dust indicated by end-members of grain size of loess in Miaodao Islands

The grain size characteristics of loess dust contain information on the transporting force of sand-storm activity and the sedimentary environment. Therefore, studying the grain size of loess can help deeply understanding the transportation and accumulation process of regional dust. This study aimed to investigate the grain size characteristics of multiple loess profiles in the Miaodao Islands, extract the transport mechanism of Miaodao loess dust through grain size end-member model analysis, and further discuss the spatial characteristics of dust transport. The findings showed that the grain size composition of the Miaodao loess was dominated by silt, followed by sand, and the clay component was the least. Sediments were poorly sorted, and the frequency curve showed a bimodal distribution. The analysis results of the grain size end-member components showed that the sand components of Miaodao loess mainly consisted of loose sediments exposed on the continental shelf through short-range jumps during the occurrence of extremely strong winter monsoon or severe storm events. Coarse silt components were transported in short-term suspension during dust events or by surface winds. The fine silt components existed in the form of floating dust after the occurrence of dust storms, and settle when the wind intensity weakens or stops, and the prevailing wind system in this area is the main driving factor for the diffusion and transportation of floating dust components. In general, Miaodao loess is mainly composed of near-source dust, and the difference in dust handling power between different islands in Miaodao Islands is not obvious, at the same time, the regional topography may also affect the dust accumulation of Miaodao loess.