Highly radiogenic Sr-isotopic signature and trace element content of grape musts from northern Piedmont vineyards (Italy)

The analysis of trace metals and metalloids, and the Sr-isotopic systematics were applied to 16 must samples from vines growing in the Sesia Val Grande Supervolcano UNESCO Global Geopark in the northern Piedmont Region (Italy), a land worldwide famous for the production of quality Nebbiolo-based red wines. Twenty-four elements were measured in each sample with inductively coupled plasma-mass spectrometry (ICP-MS). The results indicate a wide variability in trace element concentration in musts from the different vineyards. In particular, Rb and Sr reach their maximum at 5110 and 694 µg Lâ1, respectively, reflecting the geological nature of the magmatic bedrocks. Fe, Cu, Pb and Ba concentrations reach 3118, 1200, 130 and 720 µg Lâ1, respectively, suggesting a source from iron oxide, PbâZn and Ba ores associated to the volcanic activity. The87Sr/86Sr ratio is in the range 0.711608â0.718160, showing a highly radiogenic signature which is uncommon in must/wine. This is consistent with the high87Sr/86Sr isotopic ratio of the old rhyolitic bedrocks. Furthermore, the87Sr/86Sr ratio in musts linearly correlates with the corresponding87Rb/86Sr ratio, reflecting the Rb and87Sr release from primary minerals during pedogenesis and matching the initial87Sr/86Sr ratio of the parent bedrocks magmatic reservoir, thus assuming importance for authenticity assessment