OCE-PRF The impact of nitrogen loading and sea level rise on subsurface green house gas cycling and carbon sequestration in coastal salt marsh ecosystems

盐沼在气候反馈系统中发挥着重要作用。盐沼是有效的碳埋葬和排放温室气体。根据预测的气候变化，海平面上升将可能改变这些系统的碳埋藏能力。营养负荷是这些系统中的一个额外的外部压力源，可能会影响碳和温室气体循环。在这个项目中，研究员将研究海平面上升和氮富集对温室气体和碳在盐沼地下循环的影响。美国地质调查局的Kroeger博士。这位研究员计划在盐沼系统内安装一个观测威尔斯的网络，跨越氮富集和淹没水平，并在两年内每月收集溶解碳和氮的样本。此外，她将量化这些盐沼沉积物中温室气体的地下生产，在同一个月的采样过程中，将亲水性、透气性管道安装在气体分析仪上。将采取测量的间隙水通量的盐沼地下和沼泽，以确定这些成分的通量接收河口沃茨，并最终沿海海洋。该研究地点位于海平面上升的热点地区，因此是确定过去25年来海平面上升速率增加如何改变盐沼中碳埋藏的理想地点。将从经历一系列氮负荷和海水淹没水平的地点收集沉积物芯，以综合盐沼碳埋藏对这两种压力源（营养物富集和海平面上升）的反应。本研究的结果将进一步了解气候变化对盐沼生态系统服务功能的潜在影响。智力优势：地球面临着一个高二氧化碳的未来，潜在的气候影响通过全球沿海生态系统通过温度上升和海平面上升产生共鸣。沿海地区的人口增长通过营养物富集对生态系统造成了更大的压力。盐沼是高碳埋藏的区域，因此其碳储存潜力对科学界和利益相关者做出碳修复决策都很感兴趣。气候变化对盐沼生态系统的直接影响尚不清楚，但可能很大。除了储存碳的能力外，盐沼生态系统还产生和排放温室气体，如甲烷和一氧化二氮。该项目的研究结果将有助于确定盐沼中的碳埋藏在气候变化面前是否具有弹性，以及温室气体排放的净影响是否会减少或抵消盐沼作为碳汇的价值。更广泛的影响：该项目与一个较大的既定项目具有协同作用，该项目评估了氮负荷梯度上盐沼生态系统的地表温室气体逃逸和横向碳通量。该项目的一个关键组成部分是利用协作学习将科学成果转化为可用的产品，供决策者和其他对盐沼生态系统服务经济学感兴趣的人使用。有了这一框架，这项工作的结果将与有关盐沼的沿海政策决定直接挂钩。此外，扩大参与教育的机会是该项目的一个重要组成部分。第二个实地赛季将包括一名来自伍兹霍尔教育项目伙伴关系的本科生的参与。学生将在该项目的框架内进行原创性研究，并参加全国会议，介绍他们的研究成果。该研究员还将在整个项目中担任瓦奎特湾国家河口研究保护区妇女科学计划的讲师和导师。该计划允许7-9年级的年轻女性在保护区的河口研究背景下探索科学。

Overview: Salt marshes play a significant role in the climate feedback system. Salt marshes are efficient at carbon burial and emit greenhouse gases. Under predicted climate change, sea level rise will potentially alter the carbon burial capacity of these systems. Nutrient loading is an additional external stressor in these systems which may impact carbon and greenhouse gas cycling. In this project, the fellow will study the impact of sea level rise and nitrogen enrichment on subsurface cycling of greenhouse gases and carbon in salt marshes with Kevin D. Kroeger, PhD at the United States Geological Survey. The fellow plans to install a network of observing wells within a salt marsh system across nitrogen enrichment and inundation levels, and collect samples monthly for two years for dissolved carbon and nitrogen. In addition, she will quantify subsurface production of greenhouse gases in these salt marsh sediments with an installation of hydrophilic, gas permeable tubing attached to gas analyzers during the same monthly sampling. Measurements will be taken of porewater flux both within the salt marsh subsurface and out of the marsh to determine fluxes of these constituents to receiving estuarine waters and ultimately the coastal ocean. The study site exists in a sea level rise hot spot and, therefore, an ideal location to determine how enhanced rates of sea level rise over the past twenty-five years have changed carbon burial in salt marshes. Sediment cores will be collected from sites that undergo a range of nitrogen loadings and seawater inundation levels to synthesize the salt marsh carbon burial response through time to these two stressors (nutrient enrichment and sea level rise). Results from this study will further understanding of the potential climate impacts on the ecosystem services of salt marshes. Intellectual Merit: The earth is faced with a high CO2 future, with potential climate impacts resonating through global coastal ecosystems via increasing temperatures and rising sea level. Population growth in coastal regions places added stress on ecosystems via nutrient enrichment. Salt marshes are regions of high carbon burial, and as such their carbon storage potential is of interest to both the scientific community and to stakeholders making decisions about carbon remediation. The direct impact of climate change on salt marsh ecosystems is unknown, however, potentially significant. In addition to their ability to store carbon, salt marsh ecosystems also produce and emit greenhouse gases, such as methane and nitrous oxide. Research results from this project will help to determine if carbon burial in salt marshes will be resilient in the face of climate change and if the net impacts of greenhouse gas emissions will reduce or negate the value of salt marshes as a carbon sink. Broader Impacts: This project is synergistic with a larger established project evaluating surface greenhouse gas evasion and lateral carbon fluxes from salt marsh ecosystems across a gradient of nitrogen loading. A key component of this project is to use collaborative learning to transform the scientific results into useable products for policy makers and others interested in the economics of salt marsh ecosystem services. With this framework in place, the results of this work will be directly linked to coastal policy decisions regarding salt marshes. In addition, broadening participation educational opportunities are a significant component of this project. The second field season will include participation of an undergraduate student from the Woods Hole Partnership in Education Program. The student will conduct original research within the framework of this project and attend a national conference to present the findings of their research. The fellow will also serve as a lecturer and mentor in the Waquoit Bay National Estuarine Research Reserve Women in Science Program throughout the project. This program allows young women in grades 7-9 to explore science in the context of estuarine research at the Reserve.