(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的土地利用变化，城市发展和气候变化正在改变有机物和无机养分的河流输入的幅度和性质到世界各地的沿海地区和海洋。 这种长期且可能是不可逆转的，河流投入的变化可以触发全球和沿海碳预算以及沿海食品网，富营养化以及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大改善我们在河流运输过程中定量处理有机物转化的能力。在我们先前的单独研究中，我们发现南河中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表明的。 我们进一步发现了一个生物能模型，将许多简单的有机基质被氧化并纳入微生物生物量的速率和效率与这些底物的降低程度密切相关，这是根据其元素组成推论的。 初步联合研究表明，DOM的生物利用度的这两个预测指标密切相关（从理论上预期），并且同样成功。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不同？2。我们可以通过简单的散装组成措施来预测DOM的生物利用度？3。可以通过简单地测量化学氧的需求来预测DOM的生物利用度？通过使用我们的微生物生长和技术的生物能模型来描述不稳定和散装DOM池的底物降低程度，我们将研究散装和不稳定池的组成与利用率之间的关系。 我们的目标是测试为已知不稳定DOM池开发的模式，以预测大量有机物利用率和微生物生长的速率，从简单测量散装DOM池组成的简单测量。 这是一个成功的有机物利用模型，它根据简单的化学组成测量方法提供了理解微生物的因果机械过程。迄今为止，我们的工作是初步的，因为仅从几个站点收集了DOM样品，因此未使用一种系统的研究方法来研究DOM源的范围，并且当时正在开发有关生物利用性的实验的技术以及有关生物利用度的理论。 现在，我们可以严格测试我们的模型，并建议通过在具有极大对比的特征的流和河流中进行实验来做到这一点。 我们将测量有机物组成（脂肪族，芳香和过量碳以及底物还原的程度）和生物利用度（微生物生长，生长效率和有机物氧化）。基于我们的模型，应在DOM生物利用度和脂肪族C含量和DOM的底物降低程度之间观察到很强的相关性。该提案已提交给EGB计划，并由以下方式共同资助：1。 OCE的划分 - （稻）2。 Deb - （Firth）