Detection of airborne endotoxins and toxins from cyanobacterial harmful algal blooms and the effect of atmospheric oxidants on their longevity and potency

Algae and cyanobacteria naturally inhabit lakes and other aquatic environments. Some of these species can grow out of control forming dense cell concentrations or harmful algal blooms (HABs). HABs are caused by excess inputs of nutrients and warmer temperatures, and they are increasingly common in waterbodies throughout the U.S. and globally. Some cyanobacteria produce toxins (‘cyanotoxins’) that can harm people and animals, with associated economic costs due to impacts on drinking water supplies and recreational activities. Humans are exposed to these toxins through skin contact, drinking water, and eating contaminated shellfish. Less well understood is the potential inhalation of airborne cyanotoxins, which likely results from wind blowing over water surfaces that cause bubbles to burst and spread particles into the air. The goal of this research is to understand the link between cyanotoxin production during HABs to their presence and lifetime in the air. This goal will be achieved by monitoring cyanotoxins in small lakes in eastern Long Island, New York, which are known to have HABs during summer months. At the same time, air samples will be collected onto filters and examined for the presence of cyanotoxins. The research will compare these field results over multiple HAB events to assess relationships. Successful completion of this research will help close this important knowledge gap and help assess the potential impacts on human and ecosystem health. These results will be shared with local and state governmental agencies to provide information for citizens to stay healthy. Additional benefits to society result from dissemination of data that can be used to develop public policy for the management of water resources. The increase in frequency, severity, and geographical extent of HABs in aquatic ecosystems has resulted in an increased likelihood of cyanotoxin exposure in areas that experience recurrent blooms. HABs caused by Microcystis aeruginosa represent a clear example of the synergistic impact of eutrophication and warming. Excess nutrients promote increases in biomass and enhanced production of microcystins, a process that is enhanced at warmer temperatures. During a bloom, spray aerosol produced via wind blowing over the water and bubble bursting processes can incorporate intact cells, microcystins, and cell fragments that exist in respirable size fractions PM-10 and PM-2.5. This project is based on evidence that spray aerosol can promote acute respiratory distress great distances from source blooms. The overall goal of this project is to elucidate connections between cyanotoxin production in aquatic systems and airborne transport of cyanotoxins. This will be achieved through field collection of aerosolized particles using a high-volume air sampler/impaction system that allows real-time spatiotemporal collection of aerosol microcystins and endotoxins. The longevity and potency of airborne toxins will be examined considering changes in photochemical reactivity and meteorological conditions. Laboratory experiments that mimic atmospheric oxidation processes will assess the chemical stability of the airborne toxins relative to their residence time in the atmosphere. The interdisciplinary research team combines necessary expertise in HAB ecology, microbiology, environmental organic chemistry, environmental engineering, and atmospheric aerosol science to achieve the project objectives. Successful completion of this research will provide critical public health information for proactive responses to potential events at time scales relevant to the HAB management community and other relevant stakeholders. 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.