Collaborative Research: Planktonic Sources of Chromophoric Dissolved Organic Matter in Seawater

合作研究：海水中发色溶解有机物的浮游来源

• 批准号: 1547976
• 负责人: Kai Ziervogel
• 金额: $ 10万
• 依托单位: University of New Hampshire
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-07-01 至 2018-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1547976&HistoricalAwards=false
• 关键词: Collaborative; Research; Planktonic; Sources; Chromophoric

Chromophoric dissolved organic matter (CDOM) is a small but important fraction of the marine carbon pool that interacts with solar radiation and thus affects many photochemical and biological processes in the ocean. Despite its importance, the chemical basis for the formation of oceanic CDOM remains unclear. CDOM may be formed from two possible sources: 1) heterotrophic bacterial transformations of primary productivity (plankton-derived), or 2) terrestrially-derived. This project will examine the role of phytoplankton as a source of CDOM in the ocean by utilizing a powerful, new technique to measure particulate organic matter absorbance and fluorescence, discrete chemical measurements of probable precursors to planktonic CDOM, and enzymatic assays. Results of this research will provide new insights into the origin and production of planktonic CDOM and its transformation by heterotrophic bacteria. This research on CDOM will be shared broadly through a module at a North Carolina Aquarium, and streaming live feeds of shipboard activities to elementary school classrooms.Terrestrial and oceanic dissolved organic matter (DOM) differ in their chemical composition. Laboratory and open-ocean observations suggest that bacterial transformation of phytoplankton DOM produces humic-like CDOM signals that are visually similar to those in terrestrial CDOM. However, prior studies of oceanic CDOM using absorbance and fluorescence fit an electronic interaction (EI) model of intramolecular charge transfer (CT) reactions between donor and acceptor molecules common to partially-oxidized terrestrial molecules found in humic substances. This project will test the hypothesis that phytoplankton and bacteria provide a source of donors and acceptors that are microbially-transformed and linked, enabling CT contacts between them and creating oceanic CDOM. To address this, researchers will systematically study phytoplankton growth, including marine snow formation. A new technique for measuring base-extracted POM (BEPOM) absorbance and fluorescence will be used to incorporate planktonic CDOM results into the EI model, and supplemented with measurements of its probable chemical precursors. These experiments will improve understanding of how the production of CDOM in the ocean is linked to the optics and chemistry of planktonic CDOM formation. Determining the time course and extent of phytoplankton POM and DOM transformation by heterotrophic bacteria during the same phytoplankton growth experiments will provide an in-depth understanding as to how bacterial transformation of marine snow-associated planktonic organic matter drives CDOM production throughout the ocean.

散发性溶解有机物（CDOM）是海洋碳池的一小部分，与太阳辐射相互作用，从而影响海洋中的许多光化学和生物学过程。尽管它很重要，但形成海洋c的化学基础尚不清楚。 CDOM可以由两个可能的来源形成：1）原发性生产力（浮游生物衍生）或2）地面衍生的异养细菌转化。该项目将通过利用一种强大的新技术来测量颗粒物有机物吸光度和荧光，离散的化学测量，对浮游生物CDON的可能性前体进行离散化学测量和酶试验，将研究浮游植物作为海洋中CDON的作用。这项研究的结果将提供有关浮游cDom的起源和生产及其通过异养细菌转化的新见解。这项关于CDOM的研究将通过北卡罗来纳州水族馆的模块广泛共享，并将船上活动的现场饲料流向小学教室。事物和海洋溶解有机物（DOM）的化学成分不同。实验室和开放海洋的观察表明，浮游植物DOM的细菌转化产生了类似腐殖质的CDOM信号，在视觉上与陆地CDOM相似。但是，使用吸光度和荧光对海洋CDOR进行的先前研究符合供体和受体分子之间分子内电荷转移（CT）反应的电子相互作用（EI）模型。该项目将检验以下假设：浮游植物和细菌提供了微生物转换和链接的捐助者和受体的来源，从而使它们之间的CT接触并创建海洋cd。为了解决这个问题，研究人员将系统地研究浮游植物的生长，包括海洋雪的形成。一种用于测量基本提取的POM（BEPOM）吸光度和荧光的新技术，将用于将浮游生物的CDOM结果掺入EI模型中，并补充其可能的化学前体的测量。这些实验将提高人们对海洋中CDOR的产生的理解，如何与浮游生物CDOR形成的光学和化学有关。在同一浮游植物生长实验期间，确定浮游植物POM的时间过程和范围以及异养细菌的DOM转化将提供深入的理解，即对海洋雪相关的浮游生物的细菌转化如何驱动整个海洋中的CDOR生产。