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Characterizing the Atmospheric Processes of Brevetoxins in Sea Spray Aerosols Generated from Florida Red Tide
KAREN SEM, Myoseon Jang, Zechen Yu, Richard Pierce, Patricia Blum, University of Florida
Abstract Number: 204
Working Group: Remote and Regional Atmospheric Aerosol
Abstract
Florida red tide consists of high-biomass blooms of the dinoflagellate Karenia brevis, which emits polyether brevetoxins that cause neurotoxic shellfish poisoning. Sea spray aerosols (SSA) generated via wave motion during red tide events can be transferred by wind to coastal areas and can cause respiratory irritation in humans after short-term exposure. Atmospheric conditions can affect the longevity of brevetoxin contained in SSA and resulting adverse human health effects. This study characterizes the environmental conditions that lead to brevetoxin degradation in SSA during red tide events. Samples of seawater collected during a K. brevis bloom in Manasota Key, Florida are nebulized into a large outdoor photochemical chamber to mimic the atmospheric processes of aerosolized toxins. The aerosols are then atmospherically aged under various environmental conditions, including the presence or absence of sunlight, O3, OH radicals, and organic matter. Aerosols are collected during the aging process using a Particle-to-Liquid Sampler. The aerosols’ brevetoxin concentrations are measured using a conventional enzyme-linked immunoabsorbent assay (ELISA) to assess the rate and extent of their degradation. Brevetoxin decay is also confirmed by measuring concentrations with high-resolution liquid chromatography–mass spectrometry (LC–MS). Exploratory results indicate that brevetoxin concentrations in SSA decreased more rapidly in the presence of sunlight than in its absence, suggesting that reactions with OH radicals contribute largely to the algal toxin degradation. Additionally, nighttime chamber studies showed that brevetoxin decay also occurs in the presence of O3. Chamber data will be used to obtain kinetic constants for the reaction of brevetoxin with major atmospheric oxidants (O3 and OH radicals) and applied to the development of a model to predict atmospheric process of brevetoxin in SSA. This model can then assist in the development of a risk model to protect coastal communities from brevetoxin exposure during red tide events.