This session is designed to investigate how cities, and more broadly urbanization processes, influence the Main Biogeochemical Cycles, with the special focus on the Global Carbon Cycle (GCC), Nitrogen Cycle (NC) and Phosphorus cycle (PC). Since Urban air, water cycle and urban soils are substantially altered in the course of urbanisation, it becomes important to identify, classify and characterise the mechanisms of alteration from the biogeochemical point of view.

There is a clear influence of urban areas on the GCC associated with anthropogenic emissions of Greenhouse Gases (especially CO2). In terms of nitrogen (N), humans alter N sources by changing atmospheric deposition rates and by accelerating fertilizer and food production. The new emerging phenomenon is the rapid introduction of bio-fuels, which in turn requires intensification of certain crops production, and more fertilizer input. All those processes are directly linked to the areas of densely populated settlements, i.e. cities and Mega-polices.

Urban soils, playing an important role as sources, sinks and transformers in the BGC cycle, are found worldwide and represent an area of great concern for world food supply and sustainable drinking water supply, as well as aesthetics and recreation. They are located in watersheds that provide drinking water, food, waste utilization, and natural resources to cities. Urban soils also are located within cities in park areas, recreation areas, community gardens, green belts, lawns, septic absorption fields, sediment basins.

The urban water balance takes into account sources and sinks that are not always evident, especially concerning phosphorus, when the sources can cause problems when they outweigh the sinks in urban watershed.

Important existing research on the above topics will be presented in this session and also further discussed, which kind of future developments and data assembling are necessary in order to deal with urbanization, i.e. monitoring and modelling its impact on the Biosphere, under different scenarios.

The emphasis will be given to interdisciplinary approaches and forecasting, considering the problem from various points of view, namely from global and local spatial perspectives and long- and short-term temporal scales, from linear and dynamical behaviour point of view; from system's and individual actors' perspective. We also invite methodical, qualitative and quantitative investigations of the impact of urbanised air, soil and water resources on the biogeochemical cycles. Papers dealing with management strategies are very welcome. Measurements and observations should be also considered, including statistical data collection, GIS, satellite databases etc.