Collaborative Research: Deciphering drivers and variability in salt marsh lateral carbon export

合作研究：破译盐沼横向碳输出的驱动因素和变异性

• 批准号: 2242114
• 负责人: Joseph Tamborski
• 金额: $ 49.92万
• 依托单位: Old Dominion University Research Foundation
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-08-01 至 2026-07-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2242114&HistoricalAwards=false
• 关键词: Collaborative; Research; Deciphering; drivers; variability

Tidal wetlands remove large amounts of carbon dioxide from the atmosphere. Some portion of this carbon is buried as soil, often referred to as “blue carbon.” However, another portion of this carbon is exported to the coastal ocean through tidal flushing of wetland sediments. The amount of carbon exported from tidal marshes is not well known. This project investigates the processes that control carbon exports from salt marshes using state-of-the-art methods. The overarching goal of this study is to develop the first predictive model of carbon exports. This model will provide a tool for predicting future changes in coastal carbon budgets with continued sea level rise. Inclusion of lateral carbon exports as a “blue carbon” sink would greatly increase the inventory of tidal wetland carbon sinks and add to the suite of ecosystem services that are preserved through conservation and restoration of wetlands. This project will train two PhD students and provide research opportunities for multiple undergraduate students. The researchers will participate in local outreach activities to increase awareness of the science related to this project.Lateral carbon (C) exports are thought to greatly exceed C burial globally, and by as much as a factor of five along the eastern coast of North America. However, these estimates are based on limited data. At present the mechanistic drivers and environmental variables that control lateral C and total alkalinity (TA) fluxes across sites are a knowledge gap that limits scaling or modeling efforts beyond averaging a limited number of field observations. The objective of this project is to investigate the role of marsh platform inundation frequency and flooding duration, as determined by elevation within the tidal frame, as a driver and predictor of lateral C and TA exports. This project will test the hypothesis that DOC, DIC and TA export increases with decreasing marsh platform elevation within the tidal frame due to: 1) increased porewater drainage and 2) a greater proportion of dissolved C flux versus CO2 evasion. A total of six New England marsh sites at unique elevations within the tidal frame will be evaluated during a one-month summer period, capturing peak C and TA exports modulated by spring-neap tidal variation and episodic events. Variability across each site will be constrained from local measurements of respiration rates and net ecosystem exchange, soil C content and accumulation rates, and local environmental conditions. This study will quantify lateral C and TA flux through tidal creeks from high-resolution, time-series surface water measurements using an in-situ dissolved inorganic carbon (DIC) sensor, biogeochemical and physical sensors. The depths of marsh drainage and DOC/DIC/TA export will be determined from sediment 224Ra:228Th disequilibria and will be compared with fluxes determined using the surface water approach. Overall, this project will provide a comprehensive framework for the evaluation of lateral DOC/DIC/TA exports from tidal wetlands and serve as a basis for the prediction of flux magnitude and variability into a future, warmer climate.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

潮汐湿地从大气中去除大量二氧化碳，其中一部分碳被埋藏在土壤中，通常被称为“蓝碳”，然而，另一部分碳则通过湿地沉积物的潮汐冲刷而被输送到沿海海洋。潮汐沼泽的碳排放量尚不清楚，该项目利用最先进的方法研究控制盐沼碳排放的过程。该模型将为预测随着海平面持续上升而发生的沿海碳预算变化提供一个工具，将横向碳出口纳入“蓝碳”汇将大大增加潮汐湿地碳汇的库存并增加该系列。该项目将培训两名博士生，并为多名本科生提供研究机会，以提高人们对与该项目相关的科学的认识。 （三）出口据认为，全球碳埋藏量大大超过了碳埋藏量，北美东海岸的碳埋藏量高出五倍之多。然而，这些估计基于目前控制横向碳埋藏量和总碳埋藏量的机械驱动因素和环境变量。跨站点的碱度 (TA) 通量是一个知识差距，它限制了缩放或建模工作，超出了对有限数量的现场观测进行平均的范围。该项目的目标是调查沼泽平台淹没频率和洪水持续时间的作用，这取决于内部海拔。潮汐框架，作为驱动程序该项目将检验这样的假设：DOC、DIC 和 TA 输出随着潮汐框架内沼泽平台海拔的降低而增加，原因是：1）孔隙水排水增加，2）溶解的 C 通量比例更大。在为期一个月的夏季期间，将评估潮汐框架内总共六个位于独特海拔的新英格兰沼泽地，捕获受春季小潮潮汐变化和调节的峰值 C 和 TA 输出。每个地点的变异性将受到当地呼吸速率和净生态系统交换、土壤碳含量和积累速率以及当地环境条件的测量结果的限制。使用原位溶解无机碳 (DIC) 传感器、生物地球化学和物理传感器进行时间序列地表水测量 沼泽排水深度和 DOC/DIC/TA 输出将根据沉积物确定。 224Ra:228Th 不平衡，并将与使用地表水方法确定的通量进行比较总体而言，该项目将为评估潮汐湿地的横向 DOC/DIC/TA 输出提供一个全面的框架，并作为通量预测的基础。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。