This session is open to all contributions in biogeochemistry and ecology where stable isotope techniques are used as analytical tools, with a focus on stable isotopes of light elements (C, H, O, N, S, ...). We welcome studies from both terrestrial and aquatic (including marine) environments as well as methodological and experimental, and theoretical studies that introduce new approaches or techniques (including natural abundance work, labeling studies, and multi-isotope approaches, metal isotopes).