In this project the research team will gather new laboratory and field observations of sulfur-containing compounds and bioaerosols that are expected to be emitted from an exceptionally large Sargassum brown algae bloom that is anticipated to reach Florida coastlines in June or July of 2023. It is expected that this year’s plume will be larger than in previous years and the accumulation of Sargassum on coastlines, called strandings, has the potential to negatively impact southern U.S. states’ coastal ecosystems and communities. While Sargassum blooms have occurred previously, the exceptionally large size of the expected 2023 plume represents a unique opportunity to take samples and measure the likely atmospheric, environmental, and ecological impacts from the accumulation of Sargassum on coastlines and their subsequent decomposition.<br/><br/>In order to assess the impact of the Sargassum bloom, this project team will: (1) quantify hydrogen sulfide, dimethyl sulfide, and dimethyl disulfide emitted during Sargassum decomposition from samples collected in the field and observed within a laboratory chamber; (2) quantify air pollutants and bioaerosols at the site of the stranding; and (3) assess the concentrations and diversity of bacteria within air, water, sand, and Sargassum biomass samples via rRNA sequencing. The overall objective is to quantify both the short-term and the long-term impacts of Sargassum strandings on air quality and to provide new insights for researchers and policymakers. The knowledge gained during this project will increase our understanding of potential risks associated with Sargassum strandings and enable coastal communities to better prepare for and prevent adverse environmental and health impacts. Two graduate students will be supported over the course of the project and outreach to local affected communities via collaboration with the local Frost Museum of Science will be conducted.<br/><br/>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.