Collaborative Research: Novel interdisciplinary flume experiments to investigate the role of the hyporheic zone in greenhouse gas generation

合作研究：新颖的跨学科水槽实验研究潜流带在温室气体产生中的作用

• 批准号: 1141690
• 负责人: Daniele Tonina
• 金额: $ 24.76万
• 依托单位: Regents of the University of Idaho
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-06-01 至 2016-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1141690&HistoricalAwards=false
• 关键词: Collaborative; Research; Novel; interdisciplinary; flume

Collaborative Research: Novel interdisciplinary flume experiments to investigate the role of the hyporheic zone in greenhouse gas generationDaniele Tonina, University of Idaho Kevin Feris and Shawn Benner, Boise State UniversityThe hyporheic zone is the band of saturated sediment surrounding the stream, where stream waters mix with pore-water. This zone plays an important role in the nitrogen cycle, which has been radically altered by anthropogenic food and energy production. Furthermore, this zone may be a significant source of the potent greenhouse gas nitrous oxide (N2O), potentially emitting for up to 0.7 Tg y-1, equivalent to 10% of global anthropogenic N2O emissions. While the degree of hyporheic exchange is strongly influenced by stream flow and streambed topography, the relationship between those physical processes and the resulting microbially-mediated geochemical reactions leading to N2O generation and release remains poorly understood. The goal of this interdisciplinary research is to understand, quantify, and parameterize the influence of streambed hydraulics and morphology on the emission of N2O from the hyporheic zone. The generation of N2O via denitrification primarily occurs within the streambed sediments where the catalyzing microbial community is present. Therefore, the mass transport of oxygen, nitrates, ammonium and N2O by hyporheic flow strongly influences reaction rates, residence times, and subsequent N2O production. By extension, stream flow and channel morphology presumably control, and may be effective predictors of, N2O generation rates. However, a number of important in-situ processes remain poorly understood. For example, the amount of reactive nitrogen converted to N2O versus N2 is quite small (0-6%) but highly uncertain, due in part to an incomplete understanding of the genetic composition of the dominant microbial community and the hydrologic factors affecting their distribution and activity. Additionally, controls on the contribution of in-situ reactive nitrogen generation vs. that delivered by the stream are not easily determined in natural systems. Indeed, the inherent spatiotemporal complexity of natural systems limits the strength of traditional observational approaches and precludes explicit expression of these interactions in predictive mathematical models. To overcome limitations of traditional observational field approaches, this research will use a series of manipulative large-scale flume experiments. Large-scale flume experiments will provide unprecedented control while maintaining intrinsically important variables such as a realistic microbial community, water composition, stream flow, and channel structure. This research will develop new understanding of the fundamental interaction among surface-subsurface water exchange, nitrogen transformation and N2O emissions from the hyporheic zone and ultimately from streams. It will explain the role of the hyporheic zone as a biochemical transformation zone by coupling hyporheic hydraulics to biochemical reactions, through numerical-analytical models and flume experiments. Results from this work will act as building blocks for modeling N2O emissions from streams at the watershed scale. Thus, this first stage of controlled manipulative experimentation is essential in advancing our knowledge of water resources at the large scale.

合作研究：新的跨学科水槽实验，以调查在温室气体生成中的作用的潜流区Daniele Tonina，爱达荷州大学Kevin Feris和Shawn Benner，博伊西州立大学潜流区是饱和的沉积物带周围的流，流沃茨与孔隙水混合。这一地带在氮循环中起着重要作用，而人类的食物和能源生产已经从根本上改变了氮循环。此外，这一区域可能是一个重要的潜在温室气体一氧化二氮（N2 O）的来源，排放量高达0.7 Tg y-1，相当于全球人为N2 O排放量的10%。虽然潜流交换的程度受到水流和河床地形的强烈影响，但这些物理过程与导致N2 O生成和释放的微生物介导的地球化学反应之间的关系仍然知之甚少。这项跨学科研究的目标是了解，量化和参数化的河床水力学和形态的影响，从潜流区的N2 O排放。通过反硝化作用产生的N2 O主要发生在河床沉积物中，其中存在催化微生物群落。 因此，氧，硝酸盐，铵和N2 O的传质由hyporheic流强烈影响反应速率，停留时间，和随后的N2 O生产。推而广之，水流和通道形态大概控制，并可能是有效的预测，N2 O的生成率。然而，对一些重要的原地过程仍然知之甚少。例如，相对于N2，转化为N2 O的活性氮的量相当小（0-6%），但高度不确定，部分原因是对占优势的微生物群落的遗传组成和影响其分布和活性的水文因素的不完全理解。此外，在自然系统中不易确定对原位活性氮生成与由水流输送的贡献的控制。事实上，自然系统固有的时空复杂性限制了传统观测方法的优势，并排除了在预测数学模型中明确表达这些相互作用。为了克服传统观测方法的局限性，本研究将采用一系列可操作的大型水槽实验。大规模水槽实验将提供前所未有的控制，同时保持固有的重要变量，如现实的微生物群落，水的成分，水流和通道结构。这项研究将开发新的理解之间的基本相互作用的地表-地下水交换，氮转化和一氧化二氮的排放从潜流区，并最终从流。它将通过数值分析模型和水槽实验，将潜流水力学与生物化学反应相结合，解释潜流区作为生物化学转化区的作用。从这项工作的结果将作为积木模拟N2 O排放流在流域尺度。因此，这第一阶段的控制操作实验是必不可少的，在推进我们的水资源知识在大规模。