Variability of Surface Air Temperature in Italy 1870–1980

Summary The trends and the fluctuations in variability of surface air temperature in Italy has been investigated by statistical analysis of historical data covering the recent 100 years. 27 stations were used for the analysis and these were distributed all over the Italian territory divided into two climatically homogeneous zones. The temperature trends are different in each climatic zone and season, while the interannual variability shows a similar seasonal dependence for the North and South of Italy. In particular, summer temperature shows a characteristic pattern with alternating minima and maxima reaching significant values in the period 1940–1970: a maximum for the North between 1940–1960 and a minimum for the South between 1960–1970. Received February 1, 1996 Revised June 7, 1997     

Climate Variability, Climate Change and Water Resource Management in the Great Lakes

Water managers always have had to cope with climate variability. All water management practices are, to some extent, a response to natural hydrologic variability. Climate change poses a different kind of problem. Adaptation to climate change in water resource management will involve using the kinds of practices and activities currently being used. However, it remains unclear whether or not practices and activities designed with historical climate variability will be able to cope with future variability caused by atmospheric warming. This paper examines the question of adaptation to climate change in the context of Canadian water resources management, emphasizing issues in the context of the Great Lakes, an important binational water resource.     

Distribution of nitrifying activity in the Seine River (France) from Paris to the estuary

The distribution of nitrification has been measured with the H¹⁴CO₃ ⁻ incorporation method in the Seine River and its estuary during summer conditions. The Seine River below Paris receives large amounts of ammonium through wastewater discharge. In the river itself, this ammonium is only slowly nitrified, while in the estuary nitrification is rapid and complete. We show that this contrasting behavior is related to the different hydrosedimentary conditions of the two systems, as nitrifying bacteria are associated with suspended particles. In the river, particles and their attached bacteria either rapidly settle or have a sestonic behavior. Because of the short residence times of the water masses, the slow growing nitrifying population has no time to develop sufficiently to nitrify the available ammonium. The estuary is characterized by strong tidal dynamics. Particles settle and are resuspended continuously with the strong current inversions of ebb and flood. As a result of these dynamics, particles and their attached nitrifying bacteria experience longer residence times in a temporary suspended state than the water masses themselves, providing to slow growing nitrifying bacteria the opportunity to develop a large population capable of nitrifying all the available ammonium.