Aerosolization of Toxins from Harmful Algal Blooms in Freshwater and Saltwater

HOSEIN FOROUTAN, Charbel Harb, Landon Bilyeu, Regina Hanlon, Shane Ross, David Schmale, Virginia Tech

     Abstract Number: 79
     Working Group: Aerosol Sources and Constituents of Emerging Importance and Their Impacts across Spatial Scales

Abstract
Harmful algal blooms (HABs) have been observed across the globe in waterbodies ranging from large freshwater lakes, such as the Great Lakes, to smaller inland lakes and reservoirs, as well as marine coastal areas and estuaries. Spatiotemporal increases in the occurrence of HABs have been reported and associated with climate changes and nutrient over-enrichment. The main health concern around HABs is the production of cyanotoxins, which may be ingested or inhaled by human or animals. The latter exposure route, governed by the aerosolization of HABs from aquatic environments, is far less understood, and consequently a framework to forecast or quantify risks associated with airborne cyanotoxins is still lacking. Although the mechanism of aerosolization is similar to well-documented sea spray aerosols (SSAs), complexities arise from differences in physiochemical properties of freshwater and saltwater, as well as the heterogeneous presence of HABs in waterbodies. We studied the role of salinity, contrasting marine and freshwater environments, in modulating spray aerosols, and found preferential aerosolization of certain bacterial families as water salinity changes. Furthermore, through a series of laboratory experiments investigating the physics of aerosolization at the air-water interface, we highlighted mechanistic differences between spray aerosols from saltwater and freshwater. These experimental results informed a parameterization for emissions of spray aerosols generated from freshwater bodies; also know as lake spray aerosols (LSAs). Regional atmospheric simulations showed that LSA particles generated from the Great Lakes may be transported hundreds of kilometers inland. To address the heterogeneity issue, we developed a drone-based collection system to sample and characterize aerosols and cyanotoxins in water and air. The capability of the system was demonstrated in a number of field studies. Altogether, these efforts help better quantify, predict, and potentially mitigate risks associated with aerosolized HABs.