Nitrogen cycling in terrestrial and aquatic ecosystems: microbiological processes, gas fluxes, modelling,atmospheric impacts and global change feedbacks
Convener: Tuula Larmola | Co-conveners: Sami Ullah, Dianming Wu, Kristina Kleineidam, Christoph Müller, Pauline Sophie Rummel
| Attendance Mon, 04 May, 08:30–10:15 (CEST)

Anthropogenic disturbance of the nitrogen (N) cycle has more than doubled the amount of reactive N circulating in the terrestrial biosphere alone. Exchange of reactive/non-reactive nitrogen gases between land and atmosphere are strongly affecting Earth’s atmospheric composition, air quality, climate change and human health. This session seeks to improve our understanding and modelling on how global land use and climate change affect N biogeochemistry in terrestrial and aquatic ecosystems and what atmospheric interactions will be most important in influencing the climate. We seek to link microbiological N cycling processes and exchanges of nitrogen gases at the land-air interface with ecosystem dynamics, air quality and atmospheric chemistry. Despite being intensively studied for a long time, it is still difficult to predicting N transformation pathways because of our lack to quantitatively understand N cycling processes and the numerous processes contributing to (gaseous) N losses in terrestrial ecosystems. The session covers fluxes of different reactive and non-reactive nitrogen gases and the underlying transport and transformation processes in soils and sediments, e.g., fixing of atmospheric dinitrogen (N2) in ecosystems, emission/deposition of ammonia (NH3), nitric oxide (NO), nitrous oxide (N2O), nitrous acid (HONO), nitrogen dioxide (NO2), and N2 (as a result of denitrification) as well as their interactions with ozone (O3), volatile organic compounds (VOCs), free radicals and aerosols in the atmosphere, and the associated impacts on air quality. To predict processes an understanding of the soil heterogeneity is pivotal not only in surface soils and at field scale but also deeper in the soil profile and at small scales (µm). Recent technological improvements of experimental and analytical tools like measurements of N2 fluxes, linking structure and activity of functional microbial communities with flux rates, small scale resolution of soil structure, and improved numerical methods as well as computational power offer new opportunities in this area. Furthermore, the interactions of N cycling with other elemental cycles (e.g., carbon, phosphorus) in ecosystems and terrestrial-aquatic linkages, and feedbacks to biodiversity loss and water pollution will be explored. We welcome contributions covering a wide range of studies including methods development and application of new devices, observational, experimental, and modeling approaches.