Assessment of Spatio-Temporal Variability of Faecal Pollution along Coastal Waters during and after Rainfall Events

• Published in: Water (Basel) Vol. 14; no. 3; p. 502
• Main Authors: Elena Manini, Elisa Baldrighi, Fabio Ricci, Federica Grilli, Donato Giovannelli, Michele Intoccia, Silvia Casabianca, Samuela Capellacci, Nadia Marinchel, Pierluigi Penna, Fabrizio Moro, Alessandra Campanelli, Angelina Cordone, Monica Correggia, Deborah Bastoni, Luigi Bolognini, Mauro Marini, Antonella Penna
• Format: Journal Article
• Language: English
• Published: MDPI AG 01-02-2022
• Subjects: Adriatic coast; bathing waters; European Bathing Water Directive; faecal bacteria; rainfall
• ISSN: 2073-4441
• DOI: 10.3390/w14030502

More than 80% of wastewaters are discharged into rivers or seas, with a negative impact on water quality along the coast due to the presence of potential pathogens of faecal origin. Escherichia coli and enterococci are important indicators to assess, monitor, and predict microbial water quality in natural ecosystems. During rainfall events, the amount of wastewater delivered to rivers and coastal systems is increased dramatically. This study implements measures capable of monitoring the pathways of wastewater discharge to rivers and the transport of faecal bacteria to the coastal area during and following extreme rainfall events. Spatio-temporal variability of faecal microorganisms and their relationship with environmental variables and sewage outflow in an area located in the western Adriatic coast (Fano, Italy) was monitored. The daily monitoring during the rainy events was carried out for two summer seasons, for a total of five sampling periods. These results highlight that faecal microbial contaminations were related to rainy events with a high flow of wastewater, with recovery times for the microbiological indicators varying between 24 and 72 h and influenced by a dynamic dispersion. The positive correlation between ammonium and faecal bacteria at the Arzilla River and the consequences in seawater can provide a theoretical basis for controlling ammonium levels in rivers as a proxy to monitor the potential risk of bathing waters pathogen pollution.