Collaborative Research: How are estuarine carbon and alkalinity dynamics influenced by macrobiota?

合作研究：河口碳和碱度动态如何受到宏观生物群的影响？

• 批准号: 2148951
• 负责人: Cassie Gurbisz
• 金额: $ 16.18万
• 依托单位: St Mary's College of Maryland
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-07-01 至 2025-06-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2148951&HistoricalAwards=false
• 关键词: Collaborative; Research; How; estuarine; carbon

The global carbon cycle consists of the processes that transform and transport carbon on Earth. Interest in the global carbon cycle stems from its intimate connection with ecological processes and its control on atmospheric carbon dioxide, an extremely important greenhouse gas. A key feature of the global carbon cycle is the transport of carbon from land to the open ocean. Before reaching the open ocean, the carbon carried by rivers must past through estuaries, where significant transformations take place, including the interconversion of organic forms (such as carbohydrates, proteins, and lipids) and inorganic forms (carbon dioxide, bicarbonate, and carbonate) through photosynthesis and respiration. In addition to carbon, alkalinity is another important chemical quantity that is relevant to climate and life on Earth. The alkalinity is the capacity of a water body to neutralize acid and determines the extent to which carbon dioxide reacts with water to create chemical species that do not interact directly with the atmosphere. While many transformations of carbon and alkalinity in the ocean are dominated by microscopic life, like phytoplankton and bacteria, these transformations are also influenced by macroscopic life (macrobiota), such as oysters, clams, salt marshes, mangroves, and seagrasses. However, macrobiota are generally ignored in conceptual and computational models of carbon transformations in estuaries. The overall objective of this project is to improve understanding of the role that macrobiota play in estuarine carbon and alkalinity dynamics. The research will also support numerous undergraduate students, two graduate students and three post-doctoral scholars.The proposed research will be carried out through a coordinated program of field measurements, laboratory experiments, historical data analysis, and numerical modeling. Two contrasting tidal tributaries of the Chesapeake Bay, the Potomac River Estuary and the York River Estuary, will be sampled because they span much of the range of carbon and alkalinity dynamics found in estuaries worldwide and hence will facilitate the generalization of the project findings. The interdisciplinary research team will evaluate four hypotheses: (1) Tidal wetlands, such as marshes and mangroves, are a source of alkalinity to estuaries and this source increases with salinity, tidal wetland productivity, and tidal range. (2) Alkalinity sinks in estuaries are favored when riverine alkalinity is high and when benthic fauna (e.g., clams and oysters) or submerged aquatic vegetation (e.g., seagrasses) are present in sufficient quantities. (3) Alkalinity sources and sinks in estuaries are highly seasonal, with summer fluxes dominated by net calcification (due to benthic fauna and submerged aquatic vegetation, an alkalinity sink) and sulfate reduction (due to tidal wetlands, an alkalinity source) and winter fluxes due to net CaCO3 dissolution (an alkalinity source). (4) Estuaries with high-alkalinity rivers and low tidal marsh areas are sinks of alkalinity and sources of atmospheric carbon dioxide while those with low-alkalinity rivers and high tidal marsh areas are sources of alkalinity and sinks of atmospheric carbon dioxide. The research plan includes seven main elements: (1) carbonate system measurements, (2) benthic fauna distribution measurements, (3) measurements of macrobiota carbon and alkalinity fluxes, (4) development of macrobiota carbon and alkalinity flux maps, (5) historical analysis of carbonate system measurements, (6) 3-D numerical modeling, and (7) a meta-analysis that extend findings to other systems. Mentoring and inclusion will occur through the development of a research affinity group of at least eight students that will connect existing regional undergraduate research programs. Students will present their research to managers and policy makers from the Chesapeake Bay Program during annual summits and we will engage estuarine managers through presentations on macrobiota influence on biogeochemistry. This research will advance the understanding of how macrobiota influence estuarine carbon and alkalinity dynamics and, ultimately, the large-scale marine cycles of carbon and alkalinity.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.

全球碳循环包括在地球上转化和运输碳的过程。对全球碳循环的兴趣源于它与生态过程的密切联系及其对大气二氧化碳的控制，二氧化碳是一种极其重要的温室气体。全球碳循环的一个关键特征是碳从陆地运往开阔的海洋。在到达公海之前，河流携带的碳必须通过河口，那里发生了重大的变化，包括有机形式(如碳水化合物、蛋白质和脂肪)和无机形式(二氧化碳、碳酸氢盐和碳酸盐)通过光合作用和呼吸作用的相互转化。除了碳之外，碱度也是与地球上的气候和生命有关的另一个重要的化学量。碱度是水体中和酸的能力，决定了二氧化碳与水反应产生不直接与大气相互作用的化学物质的程度。虽然海洋中碳和碱度的许多变化是由浮游植物和细菌等微观生物主导的，但这些变化也受到宏观生物(大型生物群)的影响，如牡蛎、文蛤、盐沼、红树林和海草。然而，在河口碳转化的概念和计算模型中，大型生物群通常被忽略。该项目的总体目标是增进对大型生物群在河口碳和碱度动态中所起作用的了解。这项研究还将支持众多本科生、两名研究生和三名博士后奖学金。拟议的研究将通过现场测量、实验室实验、历史数据分析和数值建模的协调计划进行。切萨皮克湾的两条截然不同的潮汐支流--波托马克河河口和约克河河口--将被抽样，因为它们跨越了世界各地河口发现的碳和碱度动态的很大范围，因此将有助于项目结果的推广。跨学科研究小组将评估四个假设：(1)潮汐湿地，如沼泽和红树林，是河口碱度的来源，这个来源随着盐度、潮汐湿地生产力和潮汐范围的增加而增加。(2)当河水碱度较高，且底栖动物(如文蛤和牡蛎)或沉水水生植物(如海草)数量充足时，河口的碱度汇是有利的。(3)河口碱度源汇具有很强的季节性，夏季通量以净钙化(底栖动物和沉水植被，碱度汇)和硫酸盐还原(由于潮汐湿地，碱度源)为主，冬季通量主要由净CaCO3溶解(碱度源)主导。(4)高碱度河口和低潮沼泽区是碱度汇和大气二氧化碳源，低碱度河口和高潮沼泽区是碱度源和大气二氧化碳汇。研究计划包括七个主要内容：(1)碳酸盐系统测量，(2)底栖动物分布测量，(3)大型生物群碳和碱度通量的测量，(4)大型生物群碳和碱度通量图的编制，(5)碳酸盐系统测量的历史分析，(6)三维数值模拟，以及(7)将研究结果推广到其他系统的荟萃分析。指导和纳入将通过发展一个至少由8名学生组成的研究亲和力小组来进行，该小组将连接现有的地区性本科生研究项目。学生将在年度峰会期间向切萨皮克湾项目的经理和政策制定者展示他们的研究成果，我们将通过介绍大型生物群对生物地球化学的影响来吸引河口经理的参与。这项研究将促进对大型生物群如何影响河口碳和碱度动态以及最终影响大规模海洋碳和碱度循环的理解。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。