Investigation of Multiple Cyanotoxins in Toxic Lake Aerosols

Aerosols from freshwater lakes with toxigenic cyanobacteria pose a potentially serious threat to humans and wildlife. The most studied route of exposure to cyanotoxins is direct consumption (i.e., drinking contaminated water or eating contaminated food). However, a less studied but a potentially important route of exposure is inhalation of aerosolized cyanotoxins. Three toxins, produced by cyanobacteria, examined in this study were hepatoxicmicrocystins (MC),and the neurotoxins?-Methylamino-?-alanine (BMAA), and anatoxin-a (ATX). Using a compact lake aerosol monitor(CLAM), this study measured levels of aerosolized cyanotoxins(MC, BMAA, and ATX) at two shallow and inter-connected lakes, Walkers Pond and Lower Mill Pond (Brewster, MA, USA),biweekly throughout a sampling season (June 1-August 31). Simultaneously, toxin concentrations in lake water fractions as well as climatic parameters (temperature differential, light intensity, evaporation rate, wind velocity, and humidity)were recorded during each sample collection. The objectives of this study were to 1) determine the presence of multiple cyanotoxins in lake-generated aerosols, and 2) gain a better understanding of lake aerosols and the mechanisms behind aerosolization. xMicrocystins, BMAA, and anatoxin-a were detected in lake aerosols of Walkers Pond and Lower Mill Pond on all eight sampling dates from June 1 to August 31, 2021.Mean concentrations of aerosolized cyanotoxins (ng m-3) were generally higher at Walkers Pond for all three toxins: MC0.50 ± 0.06vs. 0.36± 0.02, BMAA 45.1 ± 8.9 vs 24.7 ± 4.3, and ATX 6.2 ± 0.8 vs. 3.9 ± 0.6, for Walkers Pond and Lower Mill Pond respectively. A consistent characteristic of the aerosolized toxins in both lakes was the dominance of the operationally defined “dissolved toxin” form