Climate impact on the carbon emission and export from Siberian inland waters (SIWA)

了解气候系统需要了解气候对陆地-水-大气耦合系统中碳循环和温室气体动力学的影响，以及它们如何反馈到气候系统中。一个主要的知识缺口是，从永久冻土中释放的碳在多大程度上以二氧化碳和甲烷的形式被运输、加工和排放到内陆水域，而不是出口到下游沿海和海洋水域。高纬度地区的湖泊和溪流向大气释放了大量的二氧化碳和甲烷。这些通量在很大程度上受到气候依赖因子（温度、风、降水）和水体水文通道的控制，要么直接控制，要么通过调节陆地碳的生产和输出6,7。特别重要的是，永久冻土融化释放的有机碳可能在很大程度上被代谢，导致二氧化碳和甲烷排放增加。不连续多年冻土区湖泊和溪流的碳排放已被证明与陆地大气碳交换相当，并超过下游的碳输出，这意味着内陆水域在碳循环中发挥了重要作用。尽管我们对湖泊和溪流中碳通量的理解取得了这些进展，但在高纬度内陆水域气候对碳运输和循环的影响方面，特别是在试图推断和预测大尺度模式和未来趋势时，仍存在基本的知识缺口。对于俄罗斯北部和北极/西伯利亚的广大地区来说尤其如此。该项目提出了西伯利亚西部跨气候梯度（北方-北极）的湖-水系网络的比较研究（图2），涵盖了大范围的永久冻土条件（缺失-零星-不连续-连续）。该项目包括：(1)对大约50个湖泊和50条溪流的CO2和CH4浓度进行实地调查，以及(2)对选定流域的年度横向和垂直碳通量进行更详细的量化。方法包括人工和连续测量溶解的有机和无机C、CO2、CH4和气体传递速度(k)，使用室和记录仪技术。同位素示踪剂（2H, 18O）采样和建模将允许估算每个集水区和水生网络的水文传输时间，并将溪流分成集水区内不同的地理流量贡献源16,17。生物测定实验将用于评估温度对降解率的依赖性，以及河流DOC在整个梯度上的总生物利用度。额外的测量包括深度，pH值，营养物质，水温，风和每个地区的排放量。所需的大部分设备在小组中已经有了。该项目将访问已建立的实地站点、该地区的数字地图以及俄罗斯托木斯克国立大学的实验室设施。根据JPI气候网站提供的旅行、会议、办公和基础设施的指导方针，项目的碳足迹将尽可能减少。对于这个项目来说，特别重要的是尽量减少旅行，办法是举行虚拟会议、安排当地工作人员进行抽样、规划会议以尽量减少旅行距离和使用夜间火车。

Understanding climate systems requires knowledge of climatic effects on C cycling andgreenhouse gas dynamics in coupled land-water-atmospheric systems, and in-turn, how thesefeedback into the climate system. A major knowledge gap is to what extent C released frompermafrost soils is transported, processed and emitted as CO2 and CH4 in inland waters vs.exported to downstream costal and ocean waters. Lakes and streams at high latitudes releasesignificant amounts of CO2 and CH4 to the atmosphere. These fluxes are largely controlledby climate dependent factors (temperature, wind, precipitation) and hydrological flowpaths towater bodies, either directly or via its regulation of the terrestrial production and export ofC6,7. Of particular importance is the organic C released from thawing permafrost which couldlargely be metabolized leading to increased CO2 and CH4 emissions. C emission fromlakes and streams in areas of discontinuous permafrost has been shown to be comparable toterrestrial atmospheric C exchange and to exceed downstream C export, implying animportant role of inland waters in the C cycle.Despite these advances in our understanding of C fluxes in lakes and streams there is afundamental knowledge gap of climate impact on C transport and cycling in inland waters athigh latitudes, and especially when attempting to extrapolate and predict large scale patternsand future trends. This is particularly true for the vast areas of boreal and arcticRussia/Siberia.This project proposes a comparative study of lake-stream networks across a climate gradient (boreal-arctic) in western Siberia (Fig. 2) covering a large range of permafrost conditions (absence-sporadic-discontinuous-continuous). The project includes (1) field surveys of CO2 and CH4 concentrations in approximately 50 lakes and 50 streams, and a more (2) detailed quantification of annual lateral and vertical C fluxes in selected catchments. Methods include a combination of manual and continuous measurements of dissolved organic and inorganic C, CO2, CH4 and gas transfer velocity (k) using chamber and logger techniques. Isotopic tracer (2H, 18O) sampling and modelling will allow hydrological transit times in each catchment and aquatic network to be estimated, and stream flow to be separated into different geographic sources of flow contribution within catchments16,17. Bioassay experiments18 will be used to assess temperature dependency in degradation rates, and in total bioavailability, of river DOC across the gradient. Additional measurements include depth, pH, nutrients, water temperature, wind, and discharge for each region. Most of the equipment needed is already available in the group. The project will have access to established field sites, digital maps of the region and to laboratory facilities at Tomsk State University, Russia.The C footprint of the project will be minimized as far as possible by following the guidelines provided by JPI Climate website for travel, meetings, office and infrastructure. For this project it is of particular importance to minimize travel by virtual meetings, by having local staff for sampling, by planning meetings to minimize travel distances and to enable use of night trains.