Anthropogenic disturbance of the nitrogen (N) cycle has more than doubled the amount of reactive N circulating in the biosphere. This session seeks to improve our understanding on how various microbial processes contribute to N cycling in terrestrial and aquatic ecosystems, how global changes impact ecosystem N biogeochemistry and what feedbacks from N cycling will be most important in influencing the climate. The presentations will cover all aspects of ecosystem N cycling, especially methodological advances in measuring and modelling of microbial N-transformation processes such as denitrification, nitrification, co-denitrification, nitrifier-denitrification, nitrate ammonification (DNRA) or anerobic ammonia oxidation (ANAMMOX), as well as their contributions to exchange of gaseous N species (N2, N2O emissions) under field-like conditions. The session will also highlight innovative isotopic, molecular and modelling methods on N cycling communities and processes at various scales, interactions with other element cycles (e.g., carbon, phosphorus), terrestrial-aquatic linkages, and feedbacks to global change.

Solicited presenter: Dr. Dolly Kothawala from Swedish University of Agricultural Sciences, Institute for Water and Environment, Uppsala, Sweden: “Controls on the dynamics of dissolved organic matter in boreal lakes”. Dr Kothawala will particularly explore the role of dissolved organic nitrogen (DON) constituents in reactivity or persistence of dissolved organic matter through freshwaters.