Where

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Our study site is the Sarno River, the most polluted river in Europe and one of the ten most polluted rivers in the world. This 24 km-long river drains a watershed area of 540 km2 and crosses three Provinces and 39 municipalities in the Campania region. Its densely populated watershed comprises 750,000-1 million inhabitants. Besides dense urbanization, river pollution can be largely attributed to the presence of numerous agro-food, tanning, and leather factories. Although efforts to improve water quality date back to 1973, fauna is almost absent, and its waters are potentially harmful for health.

Heavy metals originating mainly from the industrial activities along the river path represent the main pollutants impairing surface water quality of the Sarno River, but the river basin also includes densely urbanized areas and an intensive agricultural industry that has massive pesticide and fertilizer consumption.

The distribution of activities is clustered over the basin area, identifying tributaries characterized by a specific typology of pollution that leads to strong spatial variability and temporal fluctuations of environmental conditions. Such variability is also related to the seasonal changes in the hydrological conditions. For instance, the main tributaries (Cavaiola and Solofrana) contribute to contaminated water originating from furniture factories, ceramics, paints and tanning industries as well as agricultural activities. Moreover, the lower course of the Sarno River receives wastewater mainly from seasonal food processing and packaging industries (tomato industry), which cause discontinuous inputs. In addition, there is also one of the largest pharmaceutical facilities in the world owned by Novartis Pharma at 200 m from the river mouth.