Quantifying Sulfur and Bioaerosol Emissions from Sargassum Strandings in South Florida

SHAHAR TSAMERET, Nohhyeon Kwak, Brittany Mc Intyre, Rivka Reiner, Helena Solo-Gabriele, Jiayu Li, University of Miami

     Abstract Number: 502
     Working Group: Remote and Regional Atmospheric Aerosol

Abstract
The impacts of marine biota on atmospheric aerosols are key to understanding the climate and environmental impacts of aerosols. Recently, an addition to this field of study has been found in Sargassum, a genus of macroalgae that originates in the Atlantic and deposits onshore (stranding) in coastal areas. Sargassum provides habitat for bacteria, including those producing volatile sulfur compounds (VSCs), which are known to play a role in aerosol processes, and affect human health. While it is known that Sargassum emits VSCs, its emissions are not well quantified. We aim to provide measurements and emission factors of key VSCs from Sargassum, including hydrogen sulfide, sulfur dioxide, dimethyl sulfide, and dimethyl disulfide. Additionally, we aim to classify bioaerosols produced from Sargassum strandings. We conducted field measurements at a beach in South Florida for 2 summers (2023 and 2024), collecting bioaerosols with BioSamplers, aerosol size distribution with a GRIMM optical particle counter, and analyzing VSC concentrations with Teledyne sulfur analyzers. To supplement the field data, we recently initiated a chamber study quantifying VSC emissions from Sargassum over time, and continuously measuring bioaerosols from Sargassum microcosms with a BioSpot-VIVAS. During the first year of field sampling, no measurable Sargassum stranded at the study site. During the second year, strandings have been observed and are continuing to occur. Preliminary results from the second year show total sulfur (TS) concentrations averaging 32.1 ppbv when there is minimal stranding. The chamber study’s preliminary results indicate continued emissions at the ppb level over multiple months of decomposition. At the conclusion of this summer’s campaigns, we will present a study of Sargassum emissions and their relationships with environmental factors in the field. Our findings will be used to quantify the impacts of Sargassum strandings on coastal air quality.