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

该项目将研究在飓风和热带风暴通过后，沼泽主导的河口中溶解有机物（DOM）组成和微生物腐烂过程的变化。调查人员将把重点放在乔治亚州海岸生态系统长期生态研究（GCE-LTER）项目所在地萨皮罗岛附近的河口。经过几十年躲避大风暴的侵袭，河口在2016年10月和2017年9月分别遭受了飓风马修和飓风厄玛的袭击，2018年10月11日至12日左右可能会受到飓风迈克尔经过的强降雨的影响。虽然河流排放的脉冲可以将新鲜的、容易被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得到很好的限制。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海气通量和其他生物地球化学过程。这个项目将通过支持研究生来促进教育。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乔治亚海岸生态系统LTER组织的校园计划中传播。该计划让来自乔治亚州各地的K-12科学和数学教师沉浸在沿海过程的实践研究活动和讨论中。作为该项目的一部分产生的所有数据都将公开提供。2015-2016年，一项基于光学测量和傅里叶变换离子回旋共振质谱（FT-ICR MS）数据的长达一年的DOM组成详细调查捕捉到了飓风马修的影响，它导致河口溶解有机碳（DOC）的大量输入和DOM组成的变化。2017年的采样在飓风“厄玛”通过后不久也发现了类似的效果。微生物对DOC的消耗与DOM的组成密切相关。研究人员计划于2018年10月中旬在河口收集更多样本，届时由于内陆暴雨，预计飓风迈克尔将影响该地区。他们还将通过微生物暗孵育量化生物不稳定DOM。他们将比较未受飓风影响的背景样本和将由联合研究获得的3次飓风样本之间DOM的组成和稳定性。虽然前两次飓风在河口造成了巨大的风暴潮，但飓风迈克尔预计会带来强降雨，但风暴潮较小。连续三年发生三次主要飓风对这个河口来说是非常不寻常的，加上两个调查DOM动态的详细计划的偶然事实，为量化飓风对沼泽主导的河口有机碳输送和加工的影响提供了一个极好的机会。该奖项反映了美国国家科学基金会的法定使命，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.