Stable isotope composition of Italian bottled waters

Abstract

This study investigates the chemistry (major and minor elements) and the stable isotopic composition of water (δ18O and δ2H) and carbon in dissolved inorganic carbon (δ13CDIC) in domestic bottled waters collected on the Italian market.The hydrogen and oxygen isotope ratios of 52 samples of bottled water range from −13.8‰ to −5.5‰, for δ18O and from −99‰ to −36‰, for δ2H. This observed isotopic variability of water (δ18O and δ2H) falls within and spans most of the normal range for Italian meteoric waters suggesting that bottled water isotope ratios preserve information about the water sources from which they were derived. This investigation helped also to determine the natural origin of bottled water, and to indicate differences between the natural and production processes. The production process may influence the isotopic composition of waters. No such modification was observed for sampled waters.For identifying the origin of CO2 in waters, natural source or added exogenous CO2 of industrial origin, the 13C/12C ratio in the dissolved inorganic carbon (DIC) of carbonated bottled water is analyzed. The δ13C and δ18O, in DIC, range from −21‰ to 0.8‰ and from −25.5‰ to −7.7‰ respectively. The isotopic compositions of DIC (1.5 to −7‰) of natural sparkling Italian waters indicate that an endogenous CO2 from the deep zones of earth's crust is the origin of the gas in these waters. In still waters grouping the δ13CDIC values indicates mixing of shallow and deeper mineral water in the aquifer and interrelations between soil CO2 and the water–rock interaction. Moreover δ13CDIC values in bottled waters are in accordance with the δ13C values of the aquifers from which they are pumped out.The isotope ratio data assure that the isotopic fingerprint can be used for the authentication of bottled waters and for the certification of the source of bottled water products, and also, as a tool of characterizing an increasingly important component of the human diet. In addition, the carbon isotopic methods applied, can be used for distinguishing the origin of carbon dioxide in the bottled water for regulatory and consumer control applications.Finally, authentication and identification of CO2 origin, is an important and growing challenge to organism in certifying the quality of bottled waters and is a critical in ensuring that bottled water production does not damage the water resources.