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Inland waters are sites of active carbon (C) processing and transport along the land to ocean aquatic continuum (LOAC) that need to be accounted for closing the global C budget. Quantification of the role of the LOAC and its dynamics in the global C budget is still in its infancy, more specifically regarding its dynamics on centennial timescale that are critical for forecasting future scenarios. However, monitoring data are lacking and do not extend back as far as few decades, limiting our comprehension of the LOAC C cycle for the last centuries. To address this gap, the theme proposes to couple model approaches and an unprecedented data collection of near-annual C signatures preserved in sediments from hundreds of lakes around the world to provide new insight on C processing and transport from land to aquatic systems during the last 300 years.

• The C cycle in lakes is investigated over the last 300 years using a global biogeochemical database of lake sediments, which will be complemented with new analysis to trace past lake productivity (pigments and DNA);
• Watersheds are examined with the development of semi-empirical models of soil C exports and transports, constrained by pollen, erosion fluxes and climate paleodata
• Integration of paleolimnological data in ecosystem models will be used to present a novel development for assessing the C cycle from lake-watershed systems to global scales.

Figue 1. Sites location of our multi-proxy database, including C,N, mineral XFR scanning, CT scan and isotopes on lake sediment cores. Carbon investigation will go back and forth between local scale (methods & models development, using OLA observatory managed by CARRTEL) and global scale (C budget, spatialtemporal variability of C burial, lake typology).