Field sampling of loose erodible material: A new system to consider the full particle-size spectrum

A new system is presented to sample and enable the characterization of loose erodible material (LEM) present on a soil surface, which may be susceptible for entrainment by wind. The system uses a modified MWAC (Modified Wilson and Cooke) sediment sampler connected to a corded hand-held vacuum cleaner. Performance and accuracy of the system was tested in the laboratory using five reference soil samples with different textures. Sampling was most effective for sandy soils, while effectiveness decreases were found for soils with high silt and clay contents in dry dispersion. This effectiveness decrease can be attributed to loose silt and clay-sized particles and particle aggregates adhering to and clogging a filter attached to the MWAC outlet. Overall, the system was found to be effective in collecting sediment for most soil textures and theoretical interpretation of the measured flow speeds suggests that LEM can be sampled for a wide range of particle sizes, including dust particles. Particle-size analysis revealed that the new system is able to accurately capture the particle-size distribution (PSD) of a given sample. Only small discrepancies (maximum cumulative difference <10% at 63 μm) were found between the PSDs before and after vacuuming for all test soils. Despite limitations of the system, it is an advance toward sampling the full particle-size spectrum of loose sediment available for entrainment with the overall goal to better understand the mechanisms of dust emission and their variability.