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

RUI：沿海生态系统中再悬浮沉积物中藻类毒素（PbTx-2、PbTx-3 和微囊藻毒素-LR）的光化学转化

• 批准号: 1154850
• 负责人: Ralph Mead
• 金额: $ 67.85万
• 依托单位: University of North Carolina at Wilmington
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-05-01 至 2016-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1154850&HistoricalAwards=false
• 关键词: RUI; Photochemical; Transformations; Algal; Toxins

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.

有害藻华（HABs）是由微藻或浮游植物达到极高浓度引起的世界性现象。在这些水华期间，往往会分泌出自然产生的毒素，对环境、经济和人类健康造成各种影响，这些影响已成为全球关注的事件。在这个项目中，威尔明顿的北卡罗来纳州大学的一个研究小组将探索短毒素（PbTx-2，PbTx-3）和微囊藻毒素-LR（MLR）在阳光照射的表面沃茨重新悬浮的沿海沉积物上的光化学行为。 之所以选择这些藻毒素，是因为它们分布广泛，在溶解相中具有光化学不稳定性，而且沿海沃茨产生的藻毒素有很大一部分被有效地清除到沉积物上。研究小组假设，光化学过程将大大改变这些沉积物结合毒素的寿命，产生具有未知毒性和命运的光产物。 他们的初步证据显示，当含有该毒素的富含有机物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，他们现在想回答以下具体问题：（1）光化学过程在多大程度上改变PbTx-2，PbTx-3和MLR的再悬浮沉积物暴露于阳光下，什么是主要的光产物？(2)这些吸附毒素的光反应性如何受再悬浮物质的无机和有机组成、照射波长和悬浮泥沙浓度的影响？(3)吸附的藻毒素的光反应性如何受到重悬浮沉积物来源的地球化学环境和盐度制度的影响？ 更广泛的影响：这些问题解决了关于沿海环境中藻毒素的寿命和命运的新的、根本上重要的、具有全球意义的问题。有人认为，全球变化，包括富营养化、海水表面温度的上升以及土地使用变化和人口增长造成的径流，加剧了全世界的有害藻华。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夏季招聘当地高中科学教师。以前的高中老师把在实验室获得的经验带回课堂，大大增强了他们传达科学发现兴奋的能力。这个项目的参与者是一个本科院校的助理教授，他将在夏天把本科生带到UNCW进行这个项目的工作，并将合作收集样本。