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

点击翻译按钮获取中文摘要

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.