Isotopic composition of dissolved inorganic carbon in bottled waters on the Slovene market

This study investigates the stable isotopic composition of dissolved inorganic carbon (DIC), expressed as δ13CDIC, in domestic and foreign bottled waters randomly collected on the Slovene market. All together 58 brands and 16 replicates were analysed. The δ13CDIC values varied between −63.1‰ and +1.0‰ with an average of −12.3‰. Average δ13CDIC values for naturally sparkling, artificially sparkling, still and flavoured waters were −3.3‰, −36.5‰, −10.0‰ and −11.0‰, respectively. The lowest values are characteristic of artificial sparkling waters (minimum −63.1‰) and can be attributed to injection of industrial CO2 during bottled water production. Therefore, determination of the isotopic composition of DIC can represent a useful analytical tool to distinguish between natural and artificially sparkling waters. Furthermore, the method used enabled determination of the various origins of still waters. From the bottled waters sampled it was possible to discern waters that originate from deeper aquifers, from aquifers in equilibrium with soil CO2, or from aquifers with their recharge in a mountainous area. Finally, δ13CDIC values of flavoured waters illustrate that isotopic fractionation occurs during the production process and that δ13CDIC values in products of some producers have a large variation.