The unknown role of karst aquatic systems for terrestrial–atmospheric carbon transfer (KarLoss)

喀斯特水生系统对陆地-大气碳转移的未知作用（KarLoss）

• 批准号: 506588673
• 负责人: Professor Johannes Barth, Ph.D.
• 金额: --
• 依托单位: Lehrstuhl für Angewandte Geologie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/506588673?language=en
• 关键词: unknown; role; karst; aquatic; systems

Inland aquatic systems transport terrestrial carbon to the oceans, but also emit CO2 to the atmosphere. Some studies argue that rivers from karst terrains might act as carbon sinks and others show that they are highly oversatured with respect to CO2. Due to the large inorganic carbon reservoir of carbonates, rivers and streams in karst terrains can potentially act as strong CO2 emitters to the atmosphere. However, the role of karst catchments and their respective springs and low-order streams in the global carbon cycle remains largely unknown. In addition, the role of diel changes in CO2 patterns are so far only poorly understood. Recent developments in portable laser-based analyzers allow to measure concentrations and stable istope ratios of evading CO2 directly in the field. This allows to unravel origins, pathways and transformation processes during carbon transfer from inland aquatic systems. The application of this technique will also help to overcome limitations of mathematical models for the assessment of CO2 evasion fluxes. This study aims to enhance our understanding of the role of temperate karst aquatic systems within the global carbon cycle with focus on CO2 evasion from low-order streams and their springs. We plan spatial and temporal quantifications by direct field measurements, to disentangle and understand physical and biogeochemical processes that drive CO2 gradients in karstic headwater catchments. This aim will be reached by detailed investigations of the Wiesent karst pilot catchment in Northern Bavaria, Germany and by comparisons to nearby headwaters of two granite- and sandstone-dominated catchments. We plan regular monthly field campaigns, diel and event-based samplings. Concentrations and stable isotopes of CO2 will be measured directly in the field. This will be complemented by laboratory analyses of all carbon phases (DIC, DOC and POC) for both, isotopes and concentrations. Such a multi-parameter approach opens new modelling perspectives of CO2 evasion via isotope ratio changes. These new approaches have the potential to better constrain current CO2 transfer rates from inland aquatic systems and could establish a basis for upscaling carbon fluxes to regional or global estimates.

内陆水生系统将陆地碳输送到海洋，但也向大气排放二氧化碳。一些研究认为，喀斯特地区的河流可能起到碳汇的作用，另一些研究表明，它们对CO2的饱和度很高。由于碳酸盐的大量无机碳库，岩溶地区的河流和溪流可能成为大气中的强二氧化碳排放源。然而，岩溶集水区及其各自的泉水和低阶溪流在全球碳循环中的作用在很大程度上仍然未知。此外，昼夜变化在CO2模式中的作用迄今为止知之甚少。便携式激光分析仪的最新发展允许直接在现场测量逃避CO2的浓度和稳定同位素比。这使得解开起源，路径和转化过程中的碳转移从内陆水生系统。这种技术的应用也将有助于克服数学模型的局限性，用于评估CO2逃逸通量。本研究旨在提高我们对全球碳循环中温带岩溶水系统的作用的理解，重点是从低阶溪流及其泉水中逃逸CO2。我们计划通过直接实地测量进行空间和时间量化，以解开和理解驱动岩溶源头集水区CO2梯度的物理和地球化学过程。通过对德国巴伐利亚州北方Wiesent岩溶试点流域进行详细调查，并与附近两个以花岗岩和砂岩为主的流域的源头进行比较，将实现这一目标。我们计划每月定期进行实地活动、每日和基于事件的采样。将在现场直接测量二氧化碳的浓度和稳定同位素。这将通过对所有碳相（DIC、DOC和POC）的同位素和浓度进行实验室分析来补充。这种多参数方法开辟了通过同位素比变化的CO2逃逸的新的建模前景。这些新方法有可能更好地限制目前内陆水生系统的CO2转移率，并为将碳通量扩大到区域或全球估计值奠定基础。