(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)

9807632土地利用变化、城市发展和气候变化正在改变世界各地沿海地区和海洋的有机物和无机营养物的河流输入量和性质。 河流输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收支以及沿海食物网、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我们在定量处理河流运输过程中有机物转化的能力上有实质性的提高。在我们之前的单独研究中，我们发现，在南方河流DOM的生物有效性与DOM的脂肪族碳含量，其平均元素组成表明。 我们进一步发现，与生物能模型，许多简单的有机底物被氧化，并纳入微生物生物量的速率和效率密切相关的程度，这些底物的还原，从它们的元素组成推断。 初步的联合研究表明，这两个预测DOM的生物利用度是密切相关的（从理论上预期），大约同样成功。河流DOM的生物有效性在溪流和河流中如何变化？2.我们能否通过简单的物质组成测量来预测DOM的生物利用度？3. DOM的生物有效性可以通过简单的化学需氧量测量来预测吗？使用我们的生物能量模型的微生物生长和技术来描述不稳定和散装DOM池的底物减少的程度，我们将研究散装和不稳定池的组成和利用率之间的关系。 我们的目标是测试我们的模式，开发已知的不稳定DOM池预测散装有机物的利用率和微生物的生长，从简单的测量散装DOM池的组成。 这是一个成功的有机物利用模型，提供了一个因果关系，机械过程理解微生物的基础上简单的措施的化学成分。迄今为止，我们的工作还处于初步阶段，因为DOM样本仅从少数地点收集，没有采用系统的方法来调查一系列DOM来源，并且执行实验的技术以及有关生物利用度的理论正在开发中。时间。 我们现在能够严格地测试我们的模型，并建议通过在特征截然不同的溪流和河流中进行实验来做到这一点。 我们将测量有机物组成（脂肪族，芳香族和过量碳和底物还原程度）和生物利用度（微生物生长，生长效率和有机物氧化）。基于我们的模型，一个很强的相关性，应观察DOM的生物利用度和脂肪族C含量和底物还原度的DOM之间。该提案已提交给EGB计划，并由以下机构共同资助：1. OCE（RICE）2。DEB -（Firth）