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

有害藻华(HABS)是微藻或浮游植物达到极高浓度所引起的世界性现象。自然产生的毒素通常在这些水华期间分泌，产生各种环境、经济和人类健康影响，强调这些是全球关注的事件。在这个项目中，北卡罗来纳大学威尔明顿分校的一个研究小组将探索短杆菌毒素(PBTX-2，PBTX-3)和微囊藻毒素-LR(MLR)在阳光充足的表层水域中对再悬浮的海岸沉积物的光化学行为。之所以选择这些藻毒素，是因为它们分布广泛，在溶解相中光化学不稳定，而且沿海水域产生的很大一部分物质有效地被清除到沉积物中。该团队假设，光化学过程将极大地改变这些沉淀物结合的毒素的寿命，这些毒素产生的光产物的毒性和命运未知。他们的初步证据显示，当含有毒素的富含有机物质的沉积物重新悬浮在沿海海水中并暴露在阳光下时，溶解的PBTX-2浓度增加了40%。因此，他们现在想要回答以下具体问题：(1)光化学过程在多大程度上改变了暴露在阳光下的再悬浮沉积物上的PBTX-2、PBTX-3和MLR，以及主要的光产物是什么？(2)这些被吸附的毒素的光反应性如何受再悬浮物质的无机和有机成分、辐射波长和悬浮沉积物浓度的影响？(3)再悬浮沉积物的生物地球化学环境和盐度制度如何影响被吸附的藻毒素的光反应性？更广泛的影响：这些问题涉及与沿海环境中藻类毒素的寿命和命运有关的新的、根本上重要的、具有全球意义的问题。有人提出，全球变化，包括富营养化、海水表面温度的增加，以及变化的土地利用和人口增长带来的径流，加剧了全球范围内的赤潮。该项目每年将资助一名博士后研究员、两名硕士研究生、三名本科生和一名高中生。部分资金还将用于在暑期招聘当地高中科学教师。以前的高中老师都把在实验室获得的经验带回课堂，极大地增强了他们传达科学发现的兴奋的能力。这个项目的参与者是一名本科生机构的助理教授，他将在夏天带着本科生来联合国开发银行从事这个项目，并将合作收集样本。

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.