Quantitative detection of aerial suspension of particles with a full-frame visual camera for atmospheric wind tunnel studies

Abstract

Aerial suspension is an important process to link potential sources of particles to atmospheric transport. For contaminants like radioactive particles, pesticides or spores aerial suspension is especially relevant. We present a method that can visually quantify the suspension potential of particles in an idealized surface atmosphere system. The suspension potential of an airflow was assessed by quantifying fluorescent microplastic particles on a glass plate and exposing them to an incrementally increasing erosive wind force. In this first application of the method, we demonstrate its utility across a range of microplastic particles with regard to shape, size and polymer composition, and to detect two distinct regimes with different suspension rates. It can yield statistically robust estimates for the suspension potential of suspended fractions of up to 2500 particles at a mean areal number density of 2.6 particles per mm2. The mean wind speed at 2.7 cm height reached up to 5.2 ms−1 with a corresponding friction velocity of 0.51 ms−1. Copyright © 2021 American Association for Aerosol Research.