Atmospheric Process of Microcystins in Airborne Cyanobacterial Aerosol

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Suspensions of very small particles are called ‘aerosols’. Aerosols are commonly produced above bodies of water by breaking waves and burst bubbles at the water surface. Such aerosols can travel great distances from the point of origin. Cyanobacteria are a type of photosynthetic algae that grow in surface waters that can produce compounds known as ‘cyanotoxins.’ Many cyanotoxins are toxic to humans, and are of great concern to those people living, working, or recreating near water bodies during cyanobacterial blooms. Such events are called harmful algal blooms (HABs). While the public health threats of HABs are well recognized, there are numerous gaps in our knowledge about how cyanotoxins move in the environment, particularly through aerosolization. The goal of this research is to address this gap through the development of a model for predicting the aerosol transport of cyanotoxin produced during HABs. This goal will be achieved through three specific research objectives to: i) characterize the properties of cyanobacterial aerosols using a novel photochemical reactor to simulate atmospheric aging, ii) develop a computational model to predict the atmospheric transport of aerosolized cyanotoxins using data from laboratory study, and iii) assess the model using measurements of cyanotoxins in field samples collected during HAB events in Florida. Successful development of the model will allow accurate projections of public health risk due to HAB events. Such information would facilitate the use of proactive measures to lessen risk by public health professionals. Additional benefits to society result from increasing the Nation’s STEM workforce through the training of undergraduate and graduate student researchers.The potential for exposure to aerosolized cyanotoxins during HABs is not well studied. The goal of this multi-phase research project is to advance knowledge through the development of a mechanistic model for predicting atmospheric fate and transport of the key cyanotoxin microcystin. The project will have three specific objectives. In Objective 1, the chemical and hygroscopic properties of atmospherically aged cyanobacterial aerosols in a novel outdoor photochemical chamber will be characterized by using state-of-the-science analytical methods. In Objective 2, the Harmful Algae Atmospheric Reaction (HAAR) model will be developed to predict the atmospheric oxidation of aerosolized microcystin using chemical reaction kinetic rate constants and aerosol characteristics obtained from chamber data. In Objective 3, field data will be collected from lakes and estuaries during HAB events in Florida to evaluate atmospheric aging of aerosolized cyanotoxins. The experiments will employ the UF‐APHOR dual chambers, which allow for the quantification of atmospheric aging of complex cyanobacterial toxins and reactive chemical species under natural sunlight. The proposed HAAR model will vastly improve our ability to predict the influence of environmental factors on the fate and transport of aerosolized microcystins. Successful completion of this research will answer fundamental questions concerning the longevity of aerosolized cyanotoxins in ambient air, key information to advance the science of aerosol transport. Society will benefit from this through improved ability to predict the risk of harmful cyanobacterial aerosols in coastal and lakeside communities.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.