RUI: Photobiogeochemistry of resuspended sediments in coastal environments: Impacts on organic matter and trace metal cycling

河口和河流沉积物自然再悬浮和流动的风，波浪和水流。 在典型的浅水河口和沿海沃茨，沉积物-水的相互作用可以显著影响各种重要的地球化学过程，如微量金属的移动，营养和有机物质的循环，以及人为污染物的释放。 虽然早期的研究已经证明了重新悬浮的河口沉积物中暗释放的重要性，但他们没有解决光化学转化在这些沉积物中有机物质和金属的动员中可能发挥的更重要作用。来自北卡罗来纳州大学的科学家们，威尔明顿计划进行一系列的实地和实验室实验，以研究光转化的机制及其对环境的影响。动员的有机氮，有机碳，铜（Cu），铅（Pb）的再悬浮沉积物在两个有机丰富的沿海平原河口，其中之一是受人为活动的影响。 具体而言，本研究计划解决以下问题：（1）有多少溶解有机氮（DON），溶解有机碳（DOC），铜，和铅的光化学分解产生的再悬浮河口沉积物和光化学通量如何变化的季节和位置？(2)所产生的DON和DOC的生物利用度是多少？它如何随季节和地点而变化？(3)再悬浮沉积物的光反应性如何受源材料的无机和有机成分以及辐照波长的影响？以及（4）DON、DOC、Cu和Pb的通量如何随再悬浮物质中主要有机质矿化过程（硫酸盐还原与甲烷生成）的变化而变化？ 这项研究的结果解决了具有根本重要性和全球意义的问题，因为它考虑了有机物和金属通量在盐度变化期间的反应，例如海平面上升可能发生的变化。此外，这项工作还将提供有关光诱导反应对河口系统中有机氮、有机碳和微量金属的分布和形态的作用的信息。与该项目相关的教育影响包括对博士后以及研究生，本科生和高中生的支持和培训。 此外，预计一名高中教师将在夏季参加这项研究。

Estuarine and riverine sediments are naturally resuspended and mobilized by wind, waves, and water currents. In typically shallow estuaries and coastal waters, sediment-water interactions can significantly impact a variety of important biogeochemical processes such as trace metal mobilization, nutrient and organic matter cycling, and release of anthropogenic contaminants. While earlier studies have demonstrated the importance of dark release from resuspended estuarine sediments, they have not addressed the potentially more significant role that photochemical transformations play in the mobilization of organic matter and metals from these sediments.Scientists from the University of North Carolina, Wilmington plan to carry out a series of field and laboratory experiments to examine the mechanisms of phototransformations and the impacts they have on the mobilization of organic nitrogen, organic carbon, copper (Cu), and lead (Pb) from resuspended sediments in two organic-rich coastal plain estuaries, one of which is impacted by anthropogenic activities. Specifically, the study plans to address the following questions: (1) How much dissolved organic nitrogen (DON), dissolved organic carbon (DOC), Cu, and Pb are produced upon photolysis of resuspended estuarine sediments and how do the photochemical fluxes vary seasonally and by location?; (2) What is the bioavailability of the DON and DOC produced and how does that vary by season and location?; (3) How is the photoreactivity of resuspended sediments impacted by the inorganic and organic composition of the source material and irradiation wavelength?; and (4) How do fluxes of DON, DOC, Cu, and Pb change as the dominant organic matter remineralization processes (sulfate reduction vs. methanogenesis) in the resuspended material change?. Results from this research addresses fundamentally important and globally significant questions because it considers how fluxes of organics and metals respond during changes in salinity, such as those that could occur in rising sea levels. In addition, the work would provide information regarding the role of light-induced reactions on the distributions and speciation of organic nitrogen, organic carbon, and trace metals in estuarine systems. Educational impacts associated with this project include support and training for a postdoc, as well as graduate, undergraduate, and high school students. In addition, it is anticipated that a high school teacher would participate in the study during the summer months.