NI: CONFLUENCE - Disentangling the role of rivers as greenhouse gas conduits

NI：汇流 - 阐明河流作为温室气体管道的作用

• 批准号: NE/V009001/1
• 负责人: Joshua Dean
• 金额: $ 10.58万
• 依托单位: University of Liverpool
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2020
• 资助国家: 英国
• 起止时间: 2020 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FV009001%2F1
• 关键词: NI; CONFLUENCE; Disentangling; role; rivers

Rivers emit ~2-3 Pg of carbon as the greenhouse gas carbon dioxide (CO2) to the atmosphere, each year. This is equivalent to 20% of annual anthropogenic CO2 emissions and an important component of the global carbon cycle. Methane (CH4) emissions from river networks are very poorly understood. CH4 is a potent greenhouse gas, 34 times stronger than CO2 over a 100-year timeframe. Rivers are estimated to emit ~27 Tg of CH4 each year, equivalent to 8% of anthropogenic CH4 emissions. However, these CH4 emissions vary greatly both spatially and over time. Rivers, acting as conduits for terrestrial greenhouse gases, can thus influence ongoing climate change. Landscape disturbance, either through human activity or climate change, can enhance river carbon emissions adding substantially to an already overloaded atmospheric carbon pool. This may represent a feedback to the global climate system as river carbon emissions can be enhanced by the impact of climate change on the terrestrial carbon cycle. Characterising the magnitude and source of river carbon emissions across globally representative ecosystems is therefore urgently needed for us to understand and predict current and future climate change.Carbon emissions from rivers are primarily derived from the landscapes they drain. But sources within these landscapes can vary depending on the ecosystem. Carbon sources can include recent atmospheric CO2 fixed into biomass via photosynthesis, carbon that has accumulated in organic soils over millennia such as in Arctic, temperate and tropical peatlands, and even ancient geological carbon derived from erosion and weathering. With such a diverse range of potential carbon sources across ecosystems, it is vital to establish a framework from which to determine whether the source of carbon observed in river networks matches what would be expected from normal landscape function, or if it represents signals of a disturbed carbon cycle. I.e. are older and slower carbon cycles becoming shorter and faster?Isotopes, especially radiocarbon (14C), are a powerful tool for identifying disturbed carbon cycles. Through a network of leading researchers, this project will bring together novel techniques and study sites to serve as a foundation for in-depth investigations into river carbon emissions around the globe. The project will utilise low-cost sensors for measuring the magnitude of river carbon emissions developed by the international Project Partners. These will be combined with in-depth isotopic investigations using novel techniques developed by the UK investigators. A network of existing study site and measurement infrastructure will be established covering a diverse range of ecosystems. The project will therefore provide a springboard from which to constrain the magnitude and source of river carbon emissions through direct observations at globally representative scales.Rivers can drain large landscape areas and as such their water chemistry represents an integrated signal of landscape carbon loss. This project will provide the techniques to tease apart these signals and determine if they represent natural or disturbed carbon cycling. The project will build a database of existing observations of these signals. In addition, we will use the interacting, complimentary techniques brought together in this project to carry out a scoping project to provide preliminary observations of the magnitude and source of carbon emissions from a subset of disturbed landscapes.CONFLUENCE will also include planning for an international meeting of researchers in relevant fields to grow the network of people, techniques and sites beyond the lifetime of this project. CONFLUENCE will be used as a launchpad for consortium funding to use this unprecedented infrastructure to make a step-change in observational capability of freshwater carbon emissions at spatial and temporal scales that individual research groups alone cannot achieve.

河流每年散发出约2-3 pg的碳作为温室二氧化碳（CO2）的碳。这相当于年度人为二氧化碳排放量的20％和全球碳循环的重要组成部分。河网络的甲烷（CH4）排放率很少。 CH4是一种有效的温室气体，在100年的时间内强34倍。据估计，河流每年发射约27 tg的CH4，相当于人为CH4排放量的8％。但是，这些CH4排放量在空间和随着时间的流逝均大大差异。河流充当陆地温室气体的导管，可能会影响持续的气候变化。通过人类活动或气候变化，景观干扰可以增强河流排放，从而大大增加已经超负荷的大气碳池。这可能代表对全球气候系统的反馈，因为气候变化对陆生碳循环的影响可以增强河碳排放。因此，迫切需要表征全球代表性生态系统的河流碳排放的大小和来源，我们迫切需要了解和预测当前和未来的气候变化。河流的碳排放主要源自它们流失的景观。但是这些景观中的来源可能会根据生态系统而有所不同。碳源可以包括最近通过光合作用固定在生物质中的大气二氧化碳，碳在数千年的有机土壤中积累的碳，例如在北极，温带和热带泥炭地，甚至是源自侵蚀和风化的古代地质碳。在生态系统之间如此多种潜在的碳源范围内，至关重要的是建立一个框架，以确定在河网络中观察到的碳来源是否与正常景观功能所期望的相匹配，或者代表不受欢迎的信号碳循环。 IE。较老，较慢的碳循环是否变短，更快？同位素，尤其是放射性碳（14C），是识别受干扰碳循环的强大工具。通过一个领先的研究人员网络，该项目将汇总新的技术和研究站点，以深入研究全球河流碳排放的基础。该项目将利用低成本传感器来衡量国际项目合作伙伴开发的河流碳排放量。这些将与英国研究人员开发的新技术一起与深入的同位素研究结合使用。将建立现有研究站点和测量基础设施的网络，涵盖各种生态系统。因此，该项目将提供一个跳板，通过在全球代表性的尺度上直接观察到河流碳排放的大小和来源。河流可以耗尽大型景观区域，因此它们的水化学代表了景观碳损失的综合信号。该项目将提供嘲笑这些信号的技术，并确定它们是否代表了自然或干扰的碳循环。该项目将构建这些信号现有观察结果的数据库。此外，我们还将使用该项目中汇集的互动，免费技术来执行一个范围的项目，以提供对遇到困扰的景观部分的碳排放量和来源的初步观察。相关领域的研究人员将人们，技术和网站的网络发展到该项目的寿命之外。 Confluence将用作财团资金的发射台，以利用这种前所未有的基础设施来使淡水碳排放的观察能力在空间和时间尺度上无法实现。

项目成果

Peatland pools are tightly coupled to the contemporary carbon cycle.

• DOI: 10.1111/gcb.16999
• 发表时间: 2023-11
• 期刊: Global Change Biology
• 影响因子: 11.6
• 作者: J. Dean;M. Billett;T. E. Turner;M. Garnett;Roxane Andersen;Rebecca M McKenzie;K. Dinsmore;A. J. Baird;P. Chapman;Joseph Holden