Emissions of Harmful Algal Bloom Toxins in Freshwater Aerosol
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Harmful algal blooms (HABs) caused by cyanobacteria produce toxins (e.g., microcystin) that are harmful to human and animal health. HAB intensity and frequency are increasing across the Great Lakes and globally, raising many questions about routes of exposure to algal toxins and impacts on human health. Aerosolization of HAB toxins in marine environments by wave breaking and recreational activities has been recently studied as an inhalation route of exposure for humans but has not been thoroughly studied for freshwater environments. In these studies, lake spray aerosols (LSA) were generated in the laboratory to mimic the wave breaking induced bubble bursting that occurs in open freshwater. LSA was made from ambient freshwater samples collected at various times during a HAB and with varying levels of biological activity. Microcystin toxins were identified in freshwater and laboratory-generated aerosol particles at atmospheric concentrations up to 50 ± 20 ng/m3. Enrichment of hydrophobic microcystin congeners (e.g., microcystin-LR) was observed in aerosol particles relative to bulk freshwater and was consistent with octanol-water partitioning coefficients for these compounds. As HABs are expected to increase with a warming climate, understanding and quantifying the emissions of algal toxins into the atmosphere is crucial for evaluating the potential health consequences of HABs.