Urbanization affects air and water in Italy's Po plain

Urbanization of a natural landscape can lead to increased levels of pollution—this is well known. However, haphazard development may also produce far- reaching effects, not only in the immediate vicinity but also across regional and perhaps global scales. This presents a potential problem for several eastern and western European countries, where the urbanization rate is 3 times greater than their population growth rate [European Environment Agency, 2006]. Such disproportional changes may have major environmental, socioeconomic, and geopolitical impacts. We studied the Po Plain region in northern Italy, one of the most populated and urbanized areas in Europe, as a “pilot area” to investigate the environmental effects of urbanization. The Po Plain region (47,000 km2) covers 15% of the surface of Italy and hosts 34% of the country’s total population. Mountainous topography around the Po Plain limits air circulation with the surroundings. The region is one of the most polluted in Europe, with the city of Milan being a major world hot spot of atmospheric nitrogen dioxide (NO2). Groundwater in the region also suffers: The Po Plain is classified in European Community Nitrate Directive 91/676/EC as one of Europe’s most vulnerable areas to nitrate contamination. To investigate urban change and its effects, we conducted the Po Plain Experiment (POPLEX) in May 2014 within the central eastern part of the Po Plain, with an extension to Florence in Tuscany. We used data from multiple satellites, collected over a span of decades. We also used data from on- the- ground networks, together with hydrologic, geologic, demographic, and socioeconomic data and model estimates