Collaborative Research: Fate of Coastal Wetland Carbon Under Increasing Sea Level Rise: Using the Subsiding Louisiana Coast as a Proxy for Future World-Wide Sea Level Projections

路易斯安那州沿海目前正经历着海平面净上升的速度，其速度高于世界上大多数海岸线，并且在全球范围内，预计未来65-85年将发生海平面上升，这使路易斯安那州成为研究海平面上升对沿海系统未来潜在影响的理想地点。该项目将利用野外采集和受控水槽实验来研究沼泽土壤侵蚀引起的有机碳循环的变化及其对相关生物地球化学过程的影响。这项研究检验的假设是，大多数被侵蚀的土壤有机碳被转化为二氧化碳(CO2)并释放到大气中，这意味着增加了二氧化碳的人为输入。这一过程尚未量化，可能是大气二氧化碳变化预测模型中缺失的重要组成部分。虽然与其他来源的二氧化碳相比，这一过程在今天可能只具有区域重要性，但这项对路易斯安那州海岸的研究将极大地增强我们对全球海平面持续上升时海岸侵蚀可能对全球碳循环产生的潜在影响的充分理解。该项目将培训研究生和本科生进行涉及海洋和湿地生物地球化学、微生物学和生态建模的跨学科研究。它还将资助路易斯安那州海洋赠款一年一度的海洋骚乱教育活动，开发一个关于沿海湿地丧失的互动教育展示，该地区的初中生、教师和家长都会参加。这项研究的结果也可能为地区和世界各地的社区规划者提供信息，因为他们正在为沿海社区的海平面上升做准备。海平面上升和区域下沉在路易斯安那州造成的海岸线损失率比世界上大多数沿海地区的海岸线损失率要大得多，达到了预计在65-85年全球发生的全球海岸线损失率。这提供了一个独特的潜力，可以将路易斯安那州不断变化的沿海碳循环数据外推到海平面上升和海岸侵蚀未来影响的区域和全球模型中。通过对海岸线侵蚀的土壤有机质矿化直接导致的二氧化碳排放的重要性进行量化和建模，可以在气候变化模型中添加一个缺失的元素。这里的PIS计划通过实地采样、实验室分析、中观操作以及为正在研究的盆地建立耦合的物理-生物地球化学模型来调查沿海湿地碳库在侵蚀过程中的命运。除量化增加的二氧化碳排放外，PIs还将探讨侵蚀土壤养分输入导致富营养化加剧的可能性，以及未来因密西西比河流域过量输入养分而对墨西哥湾北部现有缺氧区的潜在贡献。

Coastal Louisiana is currently experiencing net sea level rise at rates higher than most of the world's coastlines and within the global range predicted to occur in the next 65 - 85 years, making Louisiana an ideal site to study potential future impacts of rising sea level on coastal systems. This project will use field collection and controlled tank experiments to study the changing organic carbon cycle resulting from erosion of marsh soils along with its impact on associated biogeochemical processes. The hypothesis tested in this study is that the majority of eroded soil organic carbon is converted to carbon dioxide (CO2) and released to the atmosphere, representing an addition to the anthropogenic input of CO2. This process has not been quantified and could be an important missing component in predictive models of atmospheric CO2 changes. While this process may be of only regional importance today in comparison to other sources of CO2, this study of the Louisiana coast will greatly enhance our full understanding of the potential impacts on the global carbon cycle that may result from coastal erosion as global sea level continues to rise.The project will train graduate and undergraduate students in interdisciplinary research involving marine and wetland biogeochemistry, microbiology, and ecological modeling. It will also fund development of an interactive, educational display on the loss of coastal wetlands for the Louisiana Sea Grant's annual Ocean Commotion educational event attended by area middle and high school students, teachers, and parents. Results from this study may also inform community planners both regionally and worldwide as they prepare for sea level rise in coastal communities.Eustatic sea level rise and regional subsidence have created a much greater rate of coastline loss in Louisiana than is being experienced in most of the world's coastal regions, reaching global rates that are predicted to occur worldwide in 65 - 85 years. This provides a unique potential to extrapolate data from Louisiana's changing coastal carbon cycle to both regional and global models of the future impact of sea level rise and coastal erosion. By quantifying and modeling the importance of CO2 emissions resulting directly from mineralized soil organic matter from eroding coastlines, a missing element can be added to climate change models. The PIs here plan to investigate the fate of the coastal wetland carbon pool as it erodes using field sampling, laboratory analysis, mesocosm manipulations, and the creation of a coupled physical-biogeochemical model for the basin being studied. Beyond quantifying increased CO2 emission, the PIs will also address the potential for increased eutrophication due to input of nutrients from eroded soils, as well as the potential for future contribution to existing hypoxic zones in the northern Gulf of Mexico that result from excessive nutrient input from the Mississippi River watershed.