Collaborative Research: Coupled Geochemical and Geobiological Characterization of Dissolved Organic Matter Oxidation to Carbon Dioxide

合作研究：溶解有机物氧化成二氧化碳的地球化学和地球生物学耦合表征

• 批准号: 1452039
• 负责人: David Arscott
• 金额: $ 15万
• 依托单位: Stroud Water Research Center
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-04-01 至 2018-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1452039&HistoricalAwards=false
• 关键词: Collaborative; Research; Coupled; Geochemical; Geobiological

Organic molecules dissolved in aquatic ecosystems represent the largest pool of organic matter transported through river networks and one of the most complex mixtures on Earth. The processing of these organic molecules by microorganisms resulting in their conversion to CO2 contributes to the large exchange of CO2 between the aquatic environment and the atmosphere with implications for global climate change. Despite the importance of this phenomenon, as much as 80% of the organic carbon susceptible to microbial metabolism remains unidentified. The goals of this study are to use recent advances in low through-put, ultra-high resolution analytical organic chemistry to identify and characterize the pool of biologically reactive molecules and to extend the ability of commonly used high through-put, low-resolution optical techniques to provide information about the temporal dynamics of these molecules in river networks. The outcomes of this research could advance the understanding of the link between the composition of organic molecules in a river network and the evasion of CO2 to the atmosphere, answering the question of what makes an organic molecule biodegradable. The researchers will work with educators who teach K-12 students in making processes that are invisible to the naked eye accessible and compelling as the educators develop curricula that depict the influence of molecular geochemistry and microbial geobiology to life on Earth.The researchers hypothesize that: (1) biologically reactive but molecularly uncharacterized humic molecules account for the majority of dissolved organic matter that bacteria respire to CO2; (2) the constituents of colored or fluorescent dissolved organic matter can be associated with groups of individual molecular formulas through the use of advanced statistical analyses, including Spearman Rank and 2-D correlation analyses; and (3) dissolved organic matter molecules that are ubiquitous across distant watersheds span the biological reactivity spectrum, while molecules unique to a watershed are predominantly reactive and readily converted to CO2. The research will be performed in streams within 2 well characterized river basins, one in the temperate forests of Pennsylvania and one in the tropical evergreen forests of Costa Rica. Water samples will be collected under baseflow and storm flow conditions, across stream orders and seasons, and separated into biological reactivity classes using stream water-fed plug flow bioreactors. The samples will be molecularly characterized using Fourier Transform Ion Cyclotron Resonance Mass Spectrometry as well as UV-visible absorbance and fluorescence spectra with excitation emission matrices. The successful completion of the research should advance the ability to use optical sensors to understand carbon flow through river networks and advance the understanding of the molecular nature of the dissolved organic matter that fuels the evasion of CO2 from streams and rivers to the atmosphere.

溶解在水生生态系统中的有机分子是通过河网络运输的最大有机物池，是地球上最复杂的混合物之一。微生物通过微生物对这些有机分子的加工，导致其转化为二氧化碳，从而有助于水生环境和大气之间的大量二氧化碳交换，对全球气候变化产生了影响。尽管这种现象很重要，但容易受到微生物代谢的有机碳中的80％仍然不明。 这项研究的目标是利用低渗透，超高分辨率分析有机化学的最新进展来识别和表征生物反应性分子的池，并扩展使用常用的高分辨率，低分辨率的低分辨率光学技术的能力，以提供有关这些分子在河流网络中这些时间动力学的信息。这项研究的结果可以提高人们对河网络中有机分子组成与二氧化碳逃避到大气之间的联系，从而回答了有机分子可生物降解的问题。 研究人员将与教育工作者合作，这些教育工作者在教育工作者开发课程时，可以使肉眼看不见和引人入胜的过程，这些课程描述了分子地球化学和微生物地球学对地球生命的影响。到二氧化碳； （2）通过使用先进的统计分析，包括Spearman等级和2-D相关分析，有色或荧光溶解有机物的成分可以与单个分子公式的组相关联； （3）在遥远的流域中无处不在的溶解有机物分子跨越了生物反应性谱，而流域所特有的分子主要是反应性的，并且很容易转化为CO2。这项研究将在2个特征性的河流盆地的溪流中进行，在宾夕法尼亚州的温带森林中，一间在哥斯达黎加的热带常绿森林中进行。 水样将在基流和风暴流条件下，跨流订单和季节收集，并使用溪流水的塞流生物反应器分为生物反应性类别。样品将使用傅立叶转化离子回旋共振质谱法以及具有激发发射矩阵的紫外可见吸光度和荧光光谱来分子表征。该研究的成功完成应提高使用光传感器来理解通过河网络的碳流量的能力，并提高人们对溶解有机物的分子性质的理解，从而使氧化二氧化碳从溪流和河流逃避到大气中。