Potential utility of bottled waters of Japan and of the world for groundwater isoscapes

Bottled waters are easily available in many countries. Many of them are from natural groundwater sources and contain the information of sampling location. Here, we present a dataset of stable isotope ratios for bottled waters collected from worldwide, and consider potential applications of such data for groundwater isoscape studies. We collected 349 bottles from Japan and 180 bottles from 37 nations except Japan. The oxygen and hydrogen isotope ratios of the Japanese bottled water range from -13.65 per mil to -4.93 per mil and from -90.9 per mil to -25.9 per mil, respectively. The data covers the whole of Japan. There is a clear linear relationship between delta18O and deltaD for the Japanese bottled water as; deltaD = 7.26 delta18O + 8.69 (r2= 0.93). The spatial distributions of delta18O and deltaD are very similar. Generally, the values decrease from south to north. The correlations of delta18O with the latitude and with the ground surface elevation at the sampling location are negative. The regression equation to the latitude is y=-0.35x+3.6 (r2=0.43) and to the elevation is y=-0.0028x +8.2 (r2=0.28), respectively. Thus, the latitude and altitude effects, which are commonly observed in precipitation, are also reflected to the bottled waters. We successfully present the isoscape of the Japanese bottled waters based on this dataset. The oxygen and hydrogen isotope ratios of the world bottled water range from -19.4 per mil to -0.22 per mil and from -147.7 per mil to +5.0 per mil, respectively. The relationship between delta18O and deltaD is deltaD = 8.23 delta18O + 14.09 (r2= 0.99). The large part of the samples are from the Northern Hemisphere. The weak latitude effect for delta18O is found in the Northern Hemisphere. The largest values are observed at the subtropical high pressure belt. On the other hand, the effect is unclear in the Southern Hemisphere. These patterns are similarly found in the global maps of delta18O in precipitation derived from the Global Network for Isotopes in Precipitation (GNIP). Our findings suggest that the commercial bottled waters will be a good proxy of natural environmental water on average, and a potential tool for the global isoscape studies of groundwater if samples are available from all over the world.