Collaborative Research: Impacts of atmospheric nitrogen deposition on the biogeochemistry of oligotrophic coastal waters

大气氮的沉积提供了影响氮有限地区初级生产的活性氮物质。 虽然人们普遍认为，降水中的这些物种在很大程度上有助于在许多沿海海洋系统的人为氮负荷，其生物影响仍然知之甚少。 来自宾夕法尼亚州立大学、威廉玛丽学院和老自治领大学的科学家将进行一项面向过程的实地和建模工作，以检验湿大气氮沉积物（即，降水）刺激夏季风暴后沿海沃茨中藻类生物量的初级生产力和积累，这种影响超过了美国东部贫营养沿海沃茨中由表面清新引起的风引起的混合和分层增加的相关生物地球化学反应。 为了实现他们的目标，研究人员将在夏季的几个月里在位于特拉华州湾和沿海大西洋之间的沿海沃茨进行拉格朗日实地实验，以确定表层地球化学和生物对降水事件的反应，这些事件将使用雷达和卫星数据进行识别和拦截。 关于模拟工作，将通过同化使用伴随方法获得的部分研究现场数据来校准1-D上层海洋混合模式和1-D上层海洋地球化学模式。 将使用灵敏度研究，结合原位数据和孵育实验结果，对假设进行检验。 最后，为了给实地测量和相关的一维建模提供区域和历史背景，将进行区域大气-海洋生物地球化学建模。 研究结果将纳入海洋政策和海洋地球化学研究生课程的课堂讲座。 作为该项目的一部分，将支助和培训宾夕法尼亚州立大学的一名研究生、威廉和玛丽学院的一名研究生以及旧自治领大学的一名研究生和一名本科生。

Deposition of atmospheric nitrogen provides reactive nitrogen species that influence primary production in nitrogen-limited regions. Although it is generally assumed that these species in precipitation contributes substantially to anthropogenic nitrogen loadings in many coastal marine systems, its biological impact remains poorly understood. Scientists from Pennsylvania State University, William & Mary College, and Old Dominion University will carry out a process-oriented field and modeling effort to test the hypothesis that deposits of wet atmospheric nitrogen (i.e., precipitation) stimulate primary productivity and accumulation of algal biomass in coastal waters following summer storms and this effect exceeds the associated biogeochemical responses to wind-induced mixing and increased stratification caused by surface freshening in oligotrophic coastal waters of the eastern United States. To attain their goal, the researchers would perform a Lagrangian field experiment during the summer months in coastal waters located between Delaware Bay and the coastal Carolinas to determine the response of surface-layer biogeochemistry and biology to precipitation events, which will be identified and intercepted using radar and satellite data. As regards the modeling effort, a 1-D upper ocean mixing model and a 1-D biogeochemical upper-ocean will be calibrated by assimilating the field data obtained a part of the study using the adjoint method. The hypothesis will be tested using sensitivity studies with the calibrated model combined with in-situ data and results from the incubation experiments. Lastly, to provide regional and historical context for the field measurements and the associated 1-D modeling, linked regional atmospheric-oceanic biogeochemical modeling will be conducted.Broader Impacts. Results from the study would be incorporated into class lectures for graduate courses on marine policy and marine biogeochemistry. One graduate student from Pennsylvania State University, one graduate student from the College of William and Mary, and one graduate and one undergraduate student from Old Dominion University would be supported and trained as part of this project.