Biogeochemical hot moments upon flow resumption and coupled sediment transport: A comprehensive approach for temporary and perennial stream ecosystems (FlowReSeT)

流量恢复和耦合沉积物运输时的生物地球化学热点：临时和常年河流生态系统的综合方法（FlowReSeT）

• 批准号: 437010585
• 负责人: Dr. Clara Mendoza-Lera
• 金额: --
• 依托单位: Department Fließgewässerökologie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2019
• 资助国家: 德国
• 起止时间: 2018-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/437010585?language=en
• 关键词: Biogeochemical; hot; moments; upon; flow

The project shall clarify the mechanisms that modulate streambed biogeochemistry (metabolism and nitrogen uptake of the microbial community) at various chronologies of flow resumption with and without sediment transport. The resumption of flow after drying is considered as a biogeochemical hot moment, with high rates of metabolism and nitrogen uptake influenced by the frequency of previous drying. The mechanisms modulating this hot moment are little known. Research so far were mostly single factor studies in temporary stream and river ecosystems. However intermittency and resumption of flow occurs increasingly also in perennial stream ecosystems and surface flow often implies sediment transport (e.g. migrating ripples, upper stage plane bed) especially in sandy streams. In addition, flow resumption can follow different chronologies such as instant by rain or slow by rising groundwater, and the concentrations of nutrient and carbon leached upon flow resumption can also influence the biogeochemical response. I suggest a new general concept of “intermittent stream habitats” for all areas of a streambed that dry (i.e. lack of surface water) at some point in time despite variable interactions of factors. The here proposed investigation of the mechanisms at various flow resumption chronologies, coupled sediment transport, and in temporary and perennial habitats will show if such general and integrative view can be applied. The interactions of flow resumption, sediment transport, nutrient and carbon concentrations and drying frequency will be studied in microcosm experiments with sediment communities of intermittent habitats from perennial and temporary streams. The response variables under attention are: Carbon metabolism, measured by means of changes in oxygen concentration in darkness and in light, net Nitrogen uptake by means of the addition of the stable isotope 15N (15NH4Cl) and the structure and architecture (i.e. biofilm) of the microbial community (just for coupled sediment transport). The results will contribute to a complete mechanistic picture of the Carbon and Nitrogen dynamics of lotic ecosystems prone to severe flow oscillations and drying. The findings will enable to incorporate flow resumption in the current concepts of stream biogeochemistry. Such conceptual framework is key for management of Mediterranean and more and more temperate stream ecosystems that experience drying due to increased water abstraction and climate change.

该项目应澄清在有和没有泥沙输运的情况下，在水流恢复的不同时间轴上调节河床生物地球化学（微生物群落的代谢和氮吸收）的机制。干燥后的恢复流动被认为是一个生物地球化学热时刻，高速率的代谢和氮吸收的影响，以前的干燥频率。调节这种热时刻的机制鲜为人知。迄今为止的研究大多是临时溪流和河流生态系统的单因素研究。然而，在常年河流生态系统中，水流的不稳定性和恢复也越来越多地发生，表面流往往意味着沉积物的搬运（例如迁移的波纹，上层平面床），特别是在桑迪河流中。此外，流量恢复可以遵循不同的时序，如降雨瞬间或地下水上升缓慢，以及流量恢复后沥滤的营养物质和碳的浓度也会影响生态地球化学响应。我建议一个新的一般概念的“间歇性流栖息地”的所有地区的河床干燥（即缺乏地表水）在某个时间点，尽管变量的相互作用的因素。这里提出的调查机制在不同的流量恢复年表，耦合泥沙输运，并在临时和常年栖息地将显示，如果这种一般和综合的观点可以应用。 将在对常年和临时溪流间歇性栖息地的沉积物群落进行的微观实验中研究流量恢复、沉积物输运、营养物和碳浓度以及干燥频率的相互作用。关注的响应变量是：碳代谢，通过在黑暗和光照下氧浓度的变化来测量，通过添加稳定同位素15N（15NH4Cl）和微生物群落的结构和架构（即生物膜）（仅用于耦合沉积物运输）来测量氮的净吸收。结果将有助于一个完整的机械图片的碳和氮动态的lotic生态系统容易严重的流量振荡和干燥。研究结果将使流恢复在当前的概念流地球化学。这种概念框架是管理地中海和越来越多的温带河流生态系统的关键，这些生态系统由于取水量增加和气候变化而经历干旱。