Work Package 2

WP2: Long-term variations in carbon stocks and fluxes in lentic waters

Leaders: Laurent Millet (CEN) & Jean-Philippe Jenny (CARRTEL), Participants: 8P

WP2 examines carbon (C) stocks, sources, and drivers in lentic systems over centennial and millennial timescales using sediment archives. The work addresses gaps in current datasets, especially regarding anthropogenic water bodies.

The objectives are to:

Analyze new empirical data from short sediment cores for C quality and quantity.
Assess centennial impacts of eutrophication and climate on C burial in 40 lentic systems.
Investigate millennial trends in erosion, C exports, and lentic C stocks to test the stability of these fluxes and interactions.
Tasks:

• T2.1: Assess spatial variability of modern C burial rates across 40 lentic systems, distinguishing between terrestrial and lacustrine C sources through isotopic and biomarker analyses. The task aims to build a comprehensive dataset on current C stocks and sources, particularly in small anthropogenic water bodies.
• T2.2: Investigate the impact of the Anthropocene’s « Great Acceleration » on C stocks and sources over the past 150 years. Using a paleolimnological approach, this task will evaluate shifts in C burial and sources (e.g., increased autochthonous C) due to eutrophication and human activity. The study will also explore interactions between C cycles and biodiversity.
• T2.3: Conduct a multi-millennial assessment of C stock sensitivity to disturbances in 15 lake-catchment systems. The task hypothesizes that human activities have increased C exports to lentic systems, contributing to global C budgets. Well-dated sediment records will provide insights into land cover, soil erosion, and C transfer dynamics over the last 5,000 years.

The project integrates advanced analytical methods, collaborations with national experts, and new datasets to enhance understanding of C cycling in lentic systems across diverse timescales.