Abstract:

Dust storms have serious impacts on the atmosphere and human health. It is， therefore， of great significance to identify the sources of sand and dust for preventing and controlling such storms. In this study， sand-dust samples were collected from seven points in northern China during the dust storm event on March 15， 2021， and their particle size composition and some radionuclide （²³⁵U， ²³²Th， ²²⁶Ra and ¹³⁷Cs） concentrations were measured. Results show that the sand-dust samples of Xining， Lanzhou， Xi'an， Beijing， Ji'nan and Linyi were dominated by silt particles. Radionuclide content characteristics indicate that these dust were long-distance transported Aeolian dust or blown loess nearby. Except for Zhongwei and Xi'an， ¹³⁷Cs activities of the sand-dust in the other five locations were much higher than that of cultivated land and lower than that of grassland with high vegetation coverage， indicating that they were mainly originated from eroded grasslands with low coverage rather than cultivated lands. The ¹³⁷Cs activity of the sand-dust of Xi'an was similar to that of the cultivated lands， means that these lands may be the dominate source of the sand and dust. The Zhongwei sample was coarse in grain size and extremely low in ¹³⁷Cs activity， because it was originated from the adjacent Tengger Desert.

Key words: sand and dust storm, source, radionuclides, tracing, ¹³⁷Cs