A holistic picture of spatial distribution of river polluting loads in a highly anthropized area

For many years, there has been a debate on the polluting loads affecting the Gulf of Naples, one of Italy's most spectacular and iconic landscape. The wide territory bordering the Gulf includes the Sarno river basin (SRB) managed by the Southern Apennines River Basin District Authority in the framework of Unit of Management Sarno (UoM-Sarno). The paper investigated the anthropogenic pressures and their spatial distribution in the UoM-Sarno, revealing as SRB represents a hotspot of pollution mainly due to the high population density and widespread hydro-demanding activities which are responsible of high organic and eutrophication loads. The pollution sources, variably distributed on the area, and potentially conveyed to the wastewater treatment plants (WWTPs) located into SRB, were estimated considering the WWTPs treatment capacity as well. Results revealed a holistic picture of UoM-Sarno area allowing to establish the priorities of the interventions aimed at safeguarding the coastal marine resources. In particular, 2590 tons BOD/year were directly discharged into the Gulf of Naples due to the missing of sewers, and other 10,600 tons BOD/year are potentially discharged in the Sarno river reaching the sea, considering the contribution of population, industrial activity, and livestock. [Display omitted] •Sarno flatland bears highest organic and nitrogen polluting loads.•Nitrogen load is mainly influenced by industrial activities.•Highest phosphorous loads are localized along the coast and in Sarno flatland.•Wastewater management along the cost and in the Middle Sarno is still inadequate.