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

路易斯安那州沿海地区目前正经历着比世界上大多数海岸线更高的海平面净上升速度，并且在未来65 - 85年预计发生的全球范围内，这使得路易斯安那州成为研究海平面上升对沿海系统潜在影响的理想地点。本项目将采用实地收集和控制水槽实验的方法，研究沼泽土壤侵蚀导致的有机碳循环变化及其对相关生物地球化学过程的影响。本研究检验的假设是，大部分被侵蚀的土壤有机碳转化为二氧化碳（CO2）并释放到大气中，这代表了人为输入的二氧化碳的增加。这一过程尚未被量化，可能是大气二氧化碳变化预测模型中缺失的一个重要组成部分。虽然与其他二氧化碳来源相比，这一过程在今天可能只具有区域重要性，但对路易斯安那州海岸的研究将极大地增强我们对全球碳循环的潜在影响的全面了解，随着全球海平面继续上升，海岸侵蚀可能导致全球碳循环。该项目将培养研究生和本科生进行跨学科研究，涉及海洋和湿地生物地球化学、微生物学和生态建模。它还将资助开发一个互动式的教育展示，展示沿海湿地的丧失，以供路易斯安那州海洋赠款每年举办的海洋骚动教育活动使用，该活动由该地区的中学生、教师和家长参加。这项研究的结果也可以为区域和全世界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造成的路易斯安那州海岸线的损失比世界上大多数沿海地区的损失要大得多，预计在65 - 85年内全球范围内都会发生。这为从路易斯安那州不断变化的沿海碳循环中推断出海平面上升和海岸侵蚀未来影响的区域和全球模型提供了独特的潜力。通过对海岸线侵蚀导致的矿化土壤有机质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pi计划通过实地采样、实验室分析、中观操纵和为所研究的盆地创建耦合的物理-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。除了量化增加的二氧化碳排放外，pi还将解决由于侵蚀土壤的养分输入而增加的富营养化的可能性，以及由于密西西比河流域过量的养分输入而导致的墨西哥湾北部现有缺氧区未来的潜在贡献。

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.