Consumption of bivalve shellfish harvested from water contaminated with sewage pollution presents a risk of human infections. A good understanding of the environmental factors influencing the transport and fate of faecal contaminants within the hydrological catchments is therefore essential for better targeting control measures.
This paper focuses on the relationship between rainfall incidents and the concentration of Escherichia coli measured in mussels and clams. Although an extensive number of regression models are in existence, the innovative point of this paper is the development of a model based on the Bayes Factor.
The study was conducted on the south coast of the Marche Region (Italy), a coastal area which continuously receives effluents from wastewater treatment plants. Incidents of untreated sewage overflowing as a consequence of heavy rainfall can occur and runoff from seasonal watercourses also contributes to the overall balance.
The work compared the different interpretation criteria of Bayes Factor, confirmed that E. coli concentrations in shellfish of studied area varied in correlation with rainfall events and demonstrated the effectiveness of Bayes Factor in the assessment of shellfish quality in coastal marine waters. However it suggested that further investigation is needed to determine which environmental factors provide the better basis for accurate and timely predictions.
Furthermore,the gathered data could be useful to the local authorities of Marche Region, for the purpose of designing flexible monitoring programmes which take into account the atmospheric events that could affect the proper function of sewage managing systems and the flow of the local watercourses.
