This session is designed to investigate how urban areas or cities, but 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). There are both global and local impacts, the first being Climate change (more then 97% of all the anthropogenic carbon emissions come form urban areas, aerosol formation, ammonia emissions, degradation of the ecosystems etc. Locally, urban air, water cycle, soils and urban as well as surrounding vegetation, are substantially altered in the course of urbanization. Therefore it is of a growing importance to identify, classify and characterize the mechanisms of alteration from geographical, ecological and biogeochemical points of view.

A city has a more intensive metabolism per area unit, requiring a significant inflow of artificial energy. Its consumption per urban area unit may be 3-4 orders of magnitude higher than the same for rural area. Although they take only ~2% of land, but due to their dense population settlement structure, transportation networks, energy use and altered surface characteristics, they change the Carbon and Nitrogen cycles. In the case of Nitrogen cycle, UA first “pump” nitrogen from outside (also indirectly in the form of fertilisers needed to produce food to provide for the rapidly growing urban population) , and then disperse it in the form of pollution through water and air to other ecosystems on much larger areas than their own. The new emerging phenomenon is the rapid introduction of bio-fuels, which in turn requires intensification of certain crops production, and more fertilizer input.

There is a clear influence of urban areas on the GCC associated with anthropogenic emissions of Greenhouse Gases (CO2). UA in the process if their growth, change the local Carbon balance and are responsible for the emissions from land conversion at the scale compatible to deforestation.

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 modeling 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 behavior point of view; from system's and individual actors' perspective. We also invite methodological, qualitative and quantitative investigations of the impacts. Papers dealing with management strategies are very welcome. Measurements, databases assembling and observations are also important to discuss in this session, including statistical data collection, GIS, satellite databases etc.