Stable H–O and radiogenic Sr isotopic ratios in bottled water in South Korea

Stable H–O and radiogenic Sr isotopic compositions of bottled water in South Korea were investigated to trace water origins and to elucidate hydrogeochemical water–rock interactions within aquifers. Eighty-one bottled water samples were collected across the country. The δD and δ¹⁸O values, and ⁸⁷Sr/⁸⁶Sr ratios and Sr contents of groundwater-sourced bottled water samples were in the ranges of −68 to −40 ‰, −10 to −7 ‰, 0.7050–0.8112, and 14–400 μg L⁻¹, respectively. The corresponding ranges for desalinated deep-ocean water samples were −1.2 to 1.6 ‰, −0.35 to 0.10 ‰, 0.7078–0.7092, and 12–407 μg L⁻¹, respectively. Isotopic compositions indicate spatial variations in stable isotopic signatures with geographical location, while Sr isotopic ratios are correlated with the geological characteristics of water sources. Oxygen isotopic compositions of bottled water show a negative correlation with latitude, while Sr isotopic ratios vary with aquifer geology. The integration of stable and radiogenic isotopic compositions improves our understanding of water–rock interactions, enabling accurate authentication of water sources.