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限制地区初级生产的活性氮物种。尽管人们普遍认为，降水中的这些物种对许多沿海海洋系统的人为氮负荷有很大贡献，但对其生物影响的了解仍然很少。来自宾夕法尼亚州立大学、威廉玛丽学院和老道明大学的科学家们将开展一个以过程为导向的领域和建模工作，以验证湿大气氮沉积(即，降水)刺激了夏季风暴后沿海水域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低营养沿海水域由风引起的混合和表面新鲜引起的分层增加的相关生物地球化学反应。为了实现他们的目标，研究人员将在夏季期间在特拉华湾和卡罗来纳海岸之间的沿海水域进行拉格朗日野外实验，以确定表层生物地球化学和生物学对降水事件的反应，这些降水事件将使用雷达和卫星数据进行识别和拦截。在建模工作方面，将通过吸收利用伴随方法获得的部分研究现场数据，对一维上层海洋混合模型和一维上层海洋生物地球化学模型进行校准。将使用校准模型结合现场数据和孵化实验结果的敏感性研究来检验该假设。最后，为了为野外测量和相关的1-D模拟提供区域和历史背景，将进行相关的区域大气-海洋生物地球化学模拟。更广泛的影响。这项研究的结果将纳入海洋政策和海洋生物地球化学研究生课程的课堂讲座。作为该项目的一部分，宾夕法尼亚州立大学的一名研究生、威廉与玛丽学院的一名研究生、老道明大学的一名研究生和一名本科生将得到支持和培训。

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.