(EGB) Predictions of Bioavailability of Riverine Dissolved Organic Matter from Bulk Measures of Geochemical Composition Across Landscape and Continental Gradients

(EGB) 通过景观和大陆梯度地球化学成分的整体测量来预测河流溶解有机物的生物有效性

• 批准号: 9807632
• 负责人: Charles Hopkinson
• 金额: $ 25.95万
• 依托单位: Marine Biological Laboratory
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-10-01 至 2001-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9807632&HistoricalAwards=false
• 关键词: EGB; Predictions; Bioavailability; Riverine; Dissolved

9807632Hopkinson Land-use change, urban development, and climate change are altering the magnitude and nature of riverine inputs of organic matter and inorganic nutrients to the coastal zone and oceans throughout the world. Such long-term, and probably irreversible, changes in riverine inputs can be expected to trigger corresponding changes in both global and coastal carbon budgets and in coastal food webs, eutrophication, and anoxia and species diversity. A mechanistic understanding of these changes requires a substantial improvement in our ability to treat quantitatively the transformation of organic matter during riverine transport. In our prior separate research, we found that the bioavailability of DOM in a southern river is related to the aliphatic carbon content of the DOM, as indicated by its average elemental composition. We further found with a bioenergetic model that the rate and efficiency at which many simple organic substrates are oxidized and incorporated into microbial biomass are closely related to the degree of reduction of those substrates, as deduced from their elemental composition. Preliminary joint research showed that these two predictors of bioavailability of DOM are strongly correlated (as expected from theory) and about equally successful.We plan to address 3 research questions:1. How does the bioavailability of riverine DOM vary in stream and rivers?2. Can we predict the bioavailability of DOM from simple measures of bulk composition?3. Can bioavailability of DOM be predicted from a simple measurement of chemical oxygen demand?With the use of our bioenergetic model of microbial growth and techniques to describe the degree of substrate reduction of labile and bulk DOM pools, we will examine relationships between the composition and utilization of bulk and labile pools. Our goal is to test our mode that was developed for known labile DOM pools to predict the rates of bulk organic matter utilization and microbial growth from simple measurements of the composition of the bulk DOM pool. This is a successful model of organic matter utilization that provides a causal, mechanistic processes understanding microbial on the basis of simple measures of chemical composition. Our work to date is preliminary since DOM samples were collected from only a few sites, a systematic approach to investigate a spectrum of DOM sources was not employed, and the techniques to perform the experiments as well as the theories regarding bioavailability were under development at the time. We are now in a position to rigorously test our models and propose to do so by conducting experiments in streams and rivers of greatly contrasting characteristics. We will measure organic matter composition (aliphatic, aromatic and excess carbon and degree of substrate reduction) and bioavailability (microbial growth, growth efficiency and organic matter oxidation). Based on our models, a strong correlation should be observed between DOM bioavailability and aliphatic C content and degree of substrate reduction of the DOM. This proposal was submitted to the EGB Program and is being jointly funded by:1. Division of OCE - (RIce)2. Division of DEB - (Firth)

9807632Hopkinson 土地利用变化、城市发展和气候变化正在改变河流向全世界沿海地区和海洋输入有机物质和无机养分的程度和性质。 河流投入的这种长期且可能不可逆转的变化预计将引发全球和沿海碳预算、沿海食物网、富营养化、缺氧和物种多样性的相应变化。 对这些变化的机械理解需要大幅提高我们定量处理河流运输过程中有机物转化的能力。在我们之前的单独研究中，我们发现南部河流中 DOM 的生物利用度与 DOM 的脂肪族碳含量有关，如其平均元素组成所示。 我们进一步通过生物能模型发现，许多简单有机底物被氧化并融入微生物生物质的速率和效率与这些底物的还原程度密切相关，正如从它们的元素组成推断的那样。 初步联合研究表明，DOM 生物利用度的这两个预测因子密切相关（正如理论所预期的那样）并且几乎同样成功。我们计划解决 3 个研究问题： 1．河流 DOM 的生物利用度在溪流和河流中有何变化？2．我们可以通过简单测量整体成分来预测 DOM 的生物利用度吗？3。可以通过简单测量化学需氧量来预测 DOM 的生物利用度吗？通过使用我们的微生物生长生物能模型和技术来描述不稳定和散装 DOM 池的底物还原程度，我们将检查散装和不稳定池的组成和利用之间的关系。 我们的目标是测试我们为已知不稳定 DOM 池开发的模式，通过简单测量大块 DOM 池的组成来预测大块有机物利用率和微生物生长率。 这是一个成功的有机物利用模型，它提供了基于化学成分的简单测量来理解微生物的因果、机械过程。迄今为止，我们的工作还处于初步阶段，因为 DOM 样品仅从几个地点收集，没有采用系统方法来研究一系列 DOM 来源，并且当时正在开发进行实验的技术以及有关生物利用度的理论。 我们现在能够严格测试我们的模型，并建议通过在特征截然不同的溪流和河流中进行实验来实现这一目标。 我们将测量有机物成分（脂肪族、芳香族和过量碳以及底物还原程度）和生物利用度（微生物生长、生长效率和有机物氧化）。根据我们的模型，应该观察到 DOM 生物利用度与脂肪族 C 含量以及 DOM 底物还原程度之间存在很强的相关性。该提案已提交给 EGB 计划，并由以下机构共同资助：1。 OCE 部门 - (RIce)2。 DEB 部门 - (Firth)