Quantifying dust emission potential of playa and desert surfaces in the Salton Sea Air Basin, California, United States

Abstract

Evaluating the ability of natural surfaces to generate wind driven dust emissions into the atmosphere is essential to the development and refinement of local to regional and global emissions models and the assessment of environmental hazards posed by windblown dust. Close to 3,900 individual PM₁₀ emission tests were conducted with the Portable-In Situ Wind ERosion Laboratory (PI-SWERL) between fall 2015 and spring 2021 on exposed Salton Sea playa and adjacent desert areas, California, United States. Each test location was also evaluated for surface characteristics and geomorphological unit. On playa surfaces, the crust type, presence of loose, erodible surface sand, soil moisture, and percent crust cover were found to have significant effects (P < 0.001) on PM₁₀ emission potentials. On desert surfaces, PM₁₀ emission potential varied significantly between geomorphic landforms (P < 0.001). In general, PM₁₀ emission potentials tended to be higher for desert landforms and less variable compared to playa surfaces. Highly emissive surfaces were generally dry and had sufficient loose surface sand to initiate and sustain saltation and the associated liberation of dust-sized particles. Surfaces characterized by low dust emissions exhibited moist conditions, stable crusts, or gravel lag deposits. The geometric mean potential emission rates ranged over two orders of magnitude, with a low and high of 4 and 398 μg m⁻² s⁻¹ (at an RPM of 3,000 or a u_* range of 0.56–0.73 m s⁻¹). Based on differences in surface area and emission potentials, the overall dust emissions in the study domain are dominated by emissions from desert sources.