Dust emission resulted from soil erosion by wind with significant impacts of soil (nutrient) loss and air pollution of particulate matter (PM). The ejection of dust from soil aggregates due to saltation has been hypothesized to play a major role in dust emission. Yet empirical information on the role of different aggregate sizes in dust emission is still lacking. The main goal of this study was to explore the dust emission threshold in different aggregate sizes of a semiarid loess soil. To this end, we conducted targeted wind-tunnel experiment on dust emission. The results show that dust emission from aggregate at size of 63–250 µm, 250–500 µm, and 500–1000 µm is enabled only under the conditions of saltation. The dust-PM threshold at shear velocities of 0.24–0.52 m/s depends on the aggregates size. Aggregates at the size of saltators (125–500 µm) were the most productive in dust generation by the mechanism of aggregate disintegration. In our bulk sample, the aggregate group of 63–250 µm has the highest contribution to the total dust emission. The study aimed to advance our capability in soil resources management and for model parameterization in dust emission schemes.

中文翻译：

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黄土中粉尘排放对骨料粒径的依赖性

风蚀土壤产生的扬尘对土壤（养分）损失和空气颗粒物（PM）污染有显着影响。已经假设由于盐渍化而从土壤团聚体中喷出粉尘在粉尘排放中起主要作用。然而，仍然缺乏关于不同骨料尺寸在粉尘排放中的作用的经验信息。本研究的主要目的是探索半干旱黄土不同团聚体粒径的粉尘排放阈值。为此，我们进行了有针对性的扬尘风洞试验。结果表明，63-250 µm、250-500 µm和500-1000 µm尺寸的骨料只有在跃迁条件下才能实现扬尘。剪切速度为 0.24–0.52 m/s 时的粉尘 PM 阈值取决于聚集体的大小。由于集料分解的机制，跳跃器尺寸（125-500 µm）的集料在产生粉尘方面的效率最高。在我们的散装样本中，63-250 µm 的骨料组对总粉尘排放的贡献最大。该研究旨在提高我们在土壤资源管理和粉尘排放方案模型参数化方面的能力。