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Dust Generation From Aggregate Comminution During Transport in a Laboratory Wind Tunnel.
C McKenna Neuman1, G Saarenvirta1, P O'Brien1
1Trent Environmental Wind Tunnel Trent University Peterborough ON Canada.
Journal of Geophysical Research. Atmospheres : JGR
|November 25, 2024
Summary
Particle aggregates break down during transport across playas, generating dust. Wind tunnel experiments show aggregate size decreases with distance, with rougher surfaces increasing breakdown but not dust suspension.
Area of Science:
- Earth and Planetary Sciences
- Environmental Science
- Geomorphology
Background:
- Surface-blown particle aggregates on playas contribute to interparticle bond disruption, comminution, and dust generation.
- Understanding these processes is crucial for accurate dust emission modeling and environmental management.
Purpose of the Study:
- To investigate the rate of aggregate comminution during transport.
- To examine the influence of bed roughness, humidity, and system dynamics on comminution and dust production.
- To quantify the dust production potential of aggregate comminution compared to disaggregated material.
Main Methods:
- Wind tunnel experiments using playa sediment from Owens Lake, California.
- Isolation of particle aggregates (500-710 μm) and introduction into the wind tunnel.
- Measurement of aggregate diameter changes over transport distance and capture of suspended particles on sticky plates.
Main Results:
- Aggregate diameter decreased linearly (30-56 μm/m) with transport distance (r²=0.43).
- Increased bed roughness enhanced comminution rates but did not increase dust suspension.
- Comminution produced only 0.5%-4% of suspended PM10 compared to disaggregated material.
Conclusions:
- Aggregate comminution is a significant factor in playa dust dynamics, but its contribution to suspended PM10 is relatively low.
- Wind field structure, including flow instabilities, strongly influences dust transport.
- A multidimensional approach is needed for wind tunnel simulations of dust emission, considering factors beyond friction velocity.
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