Wind tunnel experiments on dust emissions from different landform types

Abstract

The measurement and assessment of dust emissions from different landforms are important to understand the atmospheric loading of PM10 (particulate matter ≤10 µm aerodynamic diameter) and to assess natural sources of dust; however, the methodology and technique for determining the dust still present significant research challenges. In the past, specialized field observation and field wind tunnel studies have been used to understand the dust emission. A series of wind tunnel tests were carried out to identify natural sources of dust and measure the magnitudes of dust emissions from different landforms. The method used in this study allowed the measurement of the PM10 emission rate using a laboratory based environmental boundary layer wind tunnel. Results indicated that PM10 emissions demonstrated strong temporal variation and were primarily driven by aerodynamic entrainment. Sand dunes, playa, and alluvial fans had the largest dust emission rates (0.8-5.4 mg/(m 2 •s)) while sandy gravel, Gobi desert and abandoned lands had the lowest emission rates (0.003-0.126 mg/(m 2 •s)). Dust emissions were heavily dependent on the surface conditions, especially the availability of loose surface dust. High dust emissions were a result of the availability of dustparticle materials for entrainment while low dust emissions were a result of surface crusts and gravel cover. Soil surface property (surface crusts and gravel cover) plays an important role in controlling the availability of dust-sized particles for entrainment. The dust emission rate depended not only on the surface conditions but also on the friction velocity. The emission rate of PM10 varies as a power function of the friction velocity. Although dynamic abrasion processes have a strong influence on the amount of dust entrainment, aerodynamic entrainment may provide an important mechanism for dust emissions. Large volumes of dust entrained by aerodynamic entrainment cannot only occur at low shear velocity without saltation, but may dominate the entrainment process in many arid and semi-arid environments. So it may also be responsible for large magnitude dust storms. Playa and alluvial fan landforms, prior to developing a surface crust, may be the main sources of dust storms in Qinghai Province.

Emission of Fine Dust from Open Storage of Industrial Materials Exposed to Wind Erosion

“…, which is commonly used to describe the results of experimental tests performed on a variety of granular materials exposed to wind erosion [3,9,11,[41][42][43][44][45]. The correlation factor (R 2 ) was found between 0.98 and 0.99, which proves the power law function to be accurate in the description of the F D -u * relationship.…”

Investigation of the influence of mineral dust on airborne particulate matter during the COVID-19 epidemic in spring 2020 over China

“…Previous studies indicated that high clay content might prevent dust deflation ( Fecan et al, 1999 ; Wu et al, 2018 ). Fig.…”

Characteristics of Aeolian sediments transported above a gobi surface

“…Different land surface types (sand dunes, playas, alluvial fans, sandy gravel, gobi deserts, and abandoned land) have different dust emission (Wu et al, 2018). For gobis, the undisturbed land surface covered by gravel and surfaces with a biological or chemical crust have less available dust (Zhang et al, 2016), but when the gobi surface is disrupted by humans, cars, or animals, the underlying silt and clay are exposed to the wind, thereby increasing dust availability for transport (Fig.…”