Sea-Air\nTransfer of Ostreopsis Phycotoxins\nIs Driven by the Chemical Diversity of the Particulate\nFraction in the Surface Microlayer

Blooms\nof Ostreopsis cf. <i>ovata</i> pose an emerging health threat, causing respiratory\ndisorders in various coastal regions. This dinoflagellate produce\npotent phycotoxins named ovatoxins that can be transferred from the\nseawater to the atmosphere. However, the biotic and abiotic conditions\naffecting their transfer are still unknown. In this study, we investigate\nthe sea-to-air transfer of <i>O.</i> cf <i>ovata</i> phycotoxins using a process study in an aerosol reference tank (MART)\nand field observations. The process study exhibited a positive correlation\nbetween the phycotoxin content in sea spray aerosol (up to 832.59\nng m<sup>–3</sup>) and the particulate phycotoxin fraction\nin the water column and surface microlayer. In contrast, in the natural\nsystem, aerosolized phycotoxins were only observed in one out of six\nair collection (total toxins 0.59 ng m<sup>–3</sup>) despite\noptimal wind conditions. In both the process study and the natural\nsystem, ovatoxins represented only a minor fraction of the total toxin\ncontent, which was comprised of up to 90% liguriatoxins. In seawater,\nwhile no solubilized ovatoxins were detected, the concentration in\ndissolved liguriatoxin-a reached up to 19.07 μg L<sup>–1</sup>. These results underscore the need for future research on the liguriatoxins,\nand on their toxicity to establish safe exposure thresholds for beachgoers.