Comparative geochemical study between the tap waters and the bottled mineral waters in Calabria (Southern Italy) by compositional data analysis (CoDA) developments

This work focuses on comparing the inorganic content of tap and bottled mineral waters in the Calabria region (Southern Italy) performed by using robust Compositional Data Analysis (CoDA) methods and related new developments associated with a classical graphical-numerical approach. Thirty-one samples of tap waters scattered throughout the Calabrian territory and twenty-one bottled natural mineral waters of various Calabrian brands were analyzed for major and trace inorganic components. In addition, a very sensitive method based on cold vapour atomic fluorescence spectrometry (CV-AFS) has been employed to determine total mercury (HgT) concentrations. Compositional data analysis was used to identify the main interrelationships among physico-chemical parameters, highlighting the differences between the tap waters and the bottled mineral waters. Some elements, such as Al, Mn, Fe, Zn, and Pb resulted particularly enriched in the tap waters. This group of enriched elements was probably controlled by corrosion processes from metal pipes, asking for more monitoring on the state of the public distribution water network. Li, Ca, Cr, Ni, and Cd, on the other hand, appear to be mostly contributed by natural sources affecting the overall variability of the bottled mineral waters. In this context, Cr, Cu, Hg, and Pb are mainly enriched in the sparkling bottled mineral waters. Innovative compositional indices did not highlight great differences from the Maximum Allowed Concentrations (MAC) in the two types of water, so that for the health of the consumer it is indifferent to drink tap or bottled mineral water. The results represent a fundamental base to develop monitoring plans in time to check for the maintenance of quality standards.