Research Starter Grant: Consequences of saltwater intrusion on water quality in coastal plain wetlands

人类加速的气候变化将通过水文变化和海平面上升改变沿海平原湿地的功能。降雨量的减少和海平面的上升将增加咸水入侵以前淡水湿地的可能性。虽然咸水入侵对湿地植被的影响已经做了大量的工作，但对碳(C)、氮(N)和磷(P)的生物地球化学循环的影响却知之甚少。咸水入侵可通过微生物代谢和物理化学途径改变C、N和P的生物地球化学循环。微生物的代谢途径是由于电子供体和电子受体的可获得性的变化。物理化学途径是由于与沉积物的化学平衡、絮凝和阳离子交换的变化。主要目的是研究咸水入侵对滨海平原湿地C、N、P循环的影响。最重要的假设是，咸水入侵将主要通过物理化学途径增加N和P的有效性，同时减少C的有效性。这项工作将在汀布莱克湿地恢复观测站(塔)进行，这是北卡罗来纳州沿海平原的一个大型(440公顷)广泛使用仪器的湿地恢复项目。咸水入侵遗址的时空动态为检验咸水对生物地球化学循环的影响提供了独特的机会。沿海平原湿地的功能将因水文变化和海平面上升而改变。降雨量的减少和海平面的上升将增加咸水入侵以前淡水湿地的可能性。虽然咸水入侵对湿地植被的影响已经进行了大量的工作，但对其对生物地球化学循环的影响却知之甚少。咸水入侵会改变湿地中碳(C)、氮(N)和磷(P)的循环。这项研究将阐明滨海平原湿地在咸水入侵下碳、氮、磷循环耦合的重要方面。预测这些生态系统如何应对降水制度变化和海平面上升的能力，将取决于对微生物代谢以及咸水对生态系统功能的物理化学影响的了解。这项工作为基础生态系统生态学研究提供了一个独特的机会，直接影响湿地恢复的法规和实践。

Human accelerated climate change will alter the functioning of coastal plain wetlands through changes in hydrology and sea level rise. Decreased precipitation and sea level rise will increase the probability of saltwater intrusion into formerly freshwater wetlands. While much work has been conducted on the effects of saltwater intrusion on wetland vegetation, much less is known about the effects on biogeochemical cycling of carbon (C), nitrogen (N), and phosphorus (P). Saltwater intrusion can alter biogeochemical cycling of C, N, and P through both microbial metabolic and physicochemical pathways. Microbial metabolic pathways are due to changes in the availability of electron donors and acceptors. Physicochemical pathways are due to changes in chemical equilibrium, flocculation, and cation exchange with sediments. The main objective is to examine the effects of saltwater intrusion on C, N, and P cycling in coastal plain wetlands. The overarching hypothesis is that saltwater intrusion will increase N and P availability, while decreasing C availability, primarily through physicochemical pathways. The work will be conducted in the Timberlake Observatory for Wetland Restoration (TOWeR) site, a large (440 ha) extensively instrumented wetland restoration project in the coastal plain of North Carolina. The temporal and spatial dynamics of saltwater intrusion into the site provide unique opportunities to test the consequences of saltwater on biogeochemical cycling.The functioning of coastal plain wetlands will change due to alterations in hydrology and sea level rise. Decreased rainfall and sea level rise will increase the probability of saltwater intrusion into formerly freshwater wetlands. While much work has been conducted on the effects of saltwater intrusion on wetland vegetation, much less is known about the effects on biogeochemical cycling of. Saltwater intrusion can alter the cycling of carbon (C), nitrogen (N), and phosphorus (P) in the wetlands. The research proposed will illuminate vital aspects of the coupling of C, N, and P cycles in coastal plain wetlands under saltwater intrusion. The ability to predict how these ecosystems respond to altered precipitation regimes and sea level rise will depend on understanding both the microbial metabolic as well as the physicochemical effects of saltwater on ecosystem function. This work provides a unique opportunity for basic ecosystem ecology research to have a direct impact on the regulations and practice of wetland restoration.