2018 Hurricane Season: Influence on organic carbon input and biodegradation in marsh-dominated estuaries

该项目将研究溶解有机物（DOM）的组成和微生物的腐烂过程中发生的沼泽为主的河口，在飓风和热带风暴的通道的变化。调查人员将重点关注格鲁吉亚附近的萨佩洛岛周围的河口，这是格鲁吉亚沿海生态系统长期生态研究（GCE-LTER）计划的所在地。经过几十年的大风暴，河口在2016年10月受到飓风马修的袭击，2017年9月受到飓风艾玛的袭击，并且可能会受到飓风迈克尔在2018年10月11日至12日期间通过的强降雨的影响。虽然河流排放的脉冲可以提供新鲜的，容易消耗的有机物的河口，DOM交付在飓风期间对微生物过程的影响没有得到很好的约束。这一点很重要，因为微生物对DOM的处理可以影响二氧化碳的海气通量和其他生物地球化学过程。该项目将通过资助一名研究生来促进教育。这项研究的结果将在每年夏天由NSF资助的格鲁吉亚沿海生态系统LTER组织的校园计划中传播。该计划沉浸在科学和数学K-12教师从全国各地的格鲁吉亚在动手研究活动和沿海过程的讨论状态。作为该项目一部分产生的所有数据将公开提供。2015-2016年基于光学测量和傅里叶变换离子回旋共振质谱（FT-ICR MS）数据对DOM组成进行了为期一年的详细调查，捕获了飓风马修的影响，这导致了河口溶解有机碳（DOC）的显着输入和DOM组成的变化。2017年的采样在飓风厄玛通过后不久就捕捉到了类似的效果。微生物的DOC消耗被认为是密切相关的DOM组成。调查人员建议在2018年10月中旬在河口收集更多样本，当时飓风迈克尔预计将因内陆强降雨而影响该地区。他们还将通过微生物暗培养来量化生物不稳定的DOM。他们将比较不受飓风影响的背景样本和合并研究捕获的3个飓风样本之间的DOM组成和不稳定性。虽然前两次飓风在河口造成了大规模的风暴潮，但飓风迈克尔预计将造成暴雨，但风暴潮较小。连续三年发生三次大飓风对这个河口来说是极不寻常的，再加上两个调查DOM动力学的详细计划，提供了一个很好的机会来量化飓风对沼泽中有机碳输送和处理的影响-该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This project will examine changes in dissolved organic matter (DOM) composition and microbial decay processes in a marsh-dominated estuary that occur in response to the passage of hurricanes and tropical storms. The investigators will focus on the estuary around Sapelo Island off Georgia, which is the site of the Georgia Coastal Ecosystem Long Term Ecological Research (GCE-LTER) program. After decades escaping major storms, the estuary was hit by Hurricane Matthew in October 2016 and by Hurricane Irma in September 2017, and it is likely to be influenced by heavy rainfall from the passage of Hurricane Michael around October 11-12th, 2018. Although pulses in river discharge can deliver fresh, easily consumed organic matter to the estuary, the effects of DOM delivery during hurricanes on microbial processes are not well constrained. This is important because microbial processing of DOM can influence air-sea fluxes of carbon dioxide and other biogeochemical processes. This project will promote education by supporting a graduate student. Findings from this research will be disseminated in the Schoolyard Program that is organized every summer by the NSF-funded Georgia Coastal Ecosystem LTER. The program immerses science and math K-12 teachers from across the State of Georgia in hands-on research activities and discussions on coastal processes. All data generated as part of this project will be made publicly available. A detailed year-long investigation of DOM composition based on optical measurements and Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS) data in 2015-2016 captured the effects of Hurricane Matthew, which resulted in a significant input of dissolved organic carbon (DOC) and change in DOM composition in the estuary. Sampling in 2017 captured a similar effect shortly after the passage of Hurricane Irma. DOC consumption by microbes was found to be strongly tied to DOM composition. The investigators propose to collect additional samples in the estuary in mid-October 2018, when Hurricane Michael is expected to impact the region because of heavy rainfall inland. They will also quantify biologically labile DOM via microbial dark incubations. They will compare DOM composition and lability between background samples not influenced by hurricanes and samples from the 3 hurricanes that will have been captured by the combined studies. While the two earlier hurricanes caused large storm surges in the estuary, Hurricane Michael is expected to cause heavy rainfall but smaller storm surge. The occurrence of three major hurricanes in three consecutive years is highly unusual for this estuary, and together with the fortuitous fact that two detailed programs to investigate DOM dynamics were in place, provides an excellent opportunity to quantify the impact of hurricanes on organic carbon delivery and processing in a marsh-dominated estuary.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.