Morphology and Mineral Composition of Dust Particles Generated by Sandblasting From the Tengger Desert and the Ulan Buh Desert

Abstract

The Tengger Desert (TGD) and the Ulan Buh Desert (UBD) are major sources of Asian dust. To support accurate investigations into environmental and climatic impacts of dust from these deserts, we analyzed over sixty thousand individual dust particles, generated by sandblasting from their primary surface types: Gobi soils and sand dunes. TGD particles were generally smaller, rounder, and smoother than UBD's. The Gobi soil and sand dune particles of the TGD exhibited the largest number fractions at 0.5 μm and 0.5–0.6 μm in size and those of the UBD at 0.7 and 0.6 μm, respectively. Aspect ratios were similar across particles, around 1.3 roundness varied, with TGD particles averaging 0.55 (Gobi soils) and 0.50 (sand dunes) compared to UBD particles at 0.40–0.45 (Gobi soils) and 0.45 (sand dunes). Mineral analysis revealed both deserts produced particles rich in clay minerals, quartz, and other silicate particles. TGD particles contained more kaolinite and quartz, whereas UBD particles had higher chlorite and other silicates. Gypsum and halite were identified in 3.13% and 3.63% of UBD Gobi particles, respectively, indicating salt abundance in some particles; but these two salts were rarely detected in TGD particles. Comparison with data from the Taklamakan Desert revealed distinctive differences in morphology, mineral composition, and salt content. These results provide detailed source-region profiles of Asian dust particles, allowing a better involvement of nascent dust particles in field studies and numerical simulations to study their variability and roles in atmospheric chemistry and radiation transfer.