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

该项目将研究沼泽为主的河口因飓风和热带风暴的到来而发生的溶解有机物(DOM)组成和微生物衰退过程的变化。调查人员将把重点放在佐治亚州萨佩洛岛周围的河口，那里是佐治亚州海岸生态系统长期生态研究(GCE-LTER)计划的所在地。在躲避大风暴数十年后，2016年10月马修飓风和2017年9月伊尔玛飓风袭击了河口，2018年10月11日至12日左右，飓风迈克尔过境带来的强降雨很可能会影响河口。尽管河流排放中的脉冲可以将新鲜的、容易消耗的有机物输送到河口，但飓风期间DOM输送对微生物过程的影响并没有受到很好的限制。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大气-海洋通量和其他生物地球化学过程。这个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美国国家科学基金会资助的佐治亚州海岸生态系统LTER组织的校园计划中传播。该计划让来自佐治亚州各地的科学和数学K-12教师沉浸在实践研究活动和关于沿海过程的讨论中。作为该项目的一部分产生的所有数据都将公开提供。基于2015-2016年的光学测量和傅里叶变换离子回旋共振质谱仪(FT-ICR MS)数据，对DOM组成进行了长达一年的详细调查，捕捉到了飓风Matthew的影响，这导致了河口溶解有机碳(DOC)的显著输入和DOM组成的变化。2017年的采样在飓风伊尔玛过后不久就捕捉到了类似的影响。微生物对DOC的消耗被发现与DOM的组成密切相关。调查人员提议在2018年10月中旬在河口采集更多样本，届时由于内陆强降雨，飓风迈克尔预计将影响该地区。他们还将通过微生物暗培养对生物不稳定的DOM进行量化。他们将比较不受飓风影响的背景样本和联合研究将捕获的3个飓风样本之间的DOM组成和稳定性。虽然早些时候的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强降雨，但风暴潮规模较小。连续三年发生三次主要飓风对于这个河口来说是非常不寻常的，再加上两个调查DOM动态的详细计划已经到位，这为量化飓风对沼泽为主的河口有机碳输送和处理的影响提供了一个极好的机会。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。

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.