RUI: Photochemical Transformations of Algal Toxins (PbTx-2, PbTx-3 and microcystin-LR) on resuspended sediments in Coastal Ecosystems

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Harmful algal blooms (HABs) are worldwide phenomena caused by microalgae or phytoplankton reaching extremely high concentrations. Naturally occurring toxins are often secreted during these blooms, engendering a variety of environmental, economic and human health impacts that have emphasized these as events of global concern. In this project, a research team at the University of North Carolina at Wilmington will explore the photochemical behavior of brevetoxins (PbTx-2, PbTx-3) and microcystin-LR (MLR) on resuspended coastal sediments in sunlit surface waters. These algal toxins were chosen because of their widespread distribution, photochemically lability in the dissolved phase and because a significant fraction of what is produced in coastal waters is effectively scavenged onto sediments. The team hypothesizes that photochemical processes will dramatically alter the lifetime of these sediment-bound toxins producing photoproducts with unknown toxicities and fate. Their preliminary evidence revealed a 40% increase in dissolved PbTx-2 concentration when an organic-rich sediment containing the toxin was resuspended in coastal seawater and exposed to sunlight. Accordingly, they now want to answer the following specific questions: (1) To what extent do photochemical processes alter PbTx-2, PbTx-3 and MLR on resuspended sediments exposed to sunlight and what are the major photoproducts produced? (2) How are the photoreactivities of these sorbed toxins influenced by the inorganic and organic composition of the resuspended material, by irradiation wavelength, and by suspended sediment concentration? (3) How is the photoreactivity of the sorbed algal toxins affected by the biogeochemical setting and salinity regime where the resuspended sediments originate? Broader Impacts: These questions address novel, fundamentally important, globally significant questions regarding the lifetime and fate of algal toxins in coastal environments. It has been suggested that global change, including increases in eutrophication, sea surface water temperature, and runoff from changing land use and population growth, have exacerbated HABs worldwide. The project will support a post-doctoral researcher, two master's level graduate students, three undergraduates and one high school student per year. Part of the funding will also be used to recruit local high school science teachers during the summer. Previous high school teachers have taken the experience gained in the laboratory back to the classroom, greatly enhancing their ability to convey the excitement of scientific discovery. A participant on this project is an assistant professor at an undergraduate institution who will bring undergraduates to UNCW to work on the project in the summer and will collaborate in sample collection.