New Approach for Capturing and Characterizing Large Aerosolized Particles in Agricultural Settings

Atmospheric boundary-layer science is saturated with an abundance of research pertaining to aerosolized particles existing in the sub-100-micron regime. Respiratory ailments caused by aerosolized particles, such as PM 1, 2.5 and 10, have driven the vast majority of research in this specific size range. As a result, mechanical-based technology to harvest and study particles in the sub-100-micron range such as cyclone separators and cascade impactors have been greatly refined and optimized. These devices rely on Stokes settling dynamics and other aerodynamic relationships to deduce a theoretical terminal settling velocity. However, particles with characteristic lengths scales greater than 100 micron deviate from commonly applied analytical equations used for determining terminal settling velocities. The functional relationship used to describe the terminal velocity of larger particles become nonlinear functions of density, diameter, and aerodynamic resistance. Consequently, devices designed for characterizing particles in the ballistic settling regime are based on expensive methodology in many applications. We describe a low-cost high-frequency vibrating device to characterize aerosolized particles with characteristic length scales greater than 100 micron. A vertically mounted sieve shaker, called the cascade settling trap (CST), composed of anti-static and static dissipative materials was created for use in agricultural research. The CST aims to characterize large particles ejected from a standard agricultural combine used for threshing and seed collection. Initial results of size, mass, and bacterial concentration are presented from a carrot crop.