Sr isotopic signatures of Portuguese bottled mineral waters, their relationships with the geological setting and potential use for product authentication
The Sr isotopic ratios of nine bottled
natural mineral waters from Portugal were
measured in the Laboratory of Isotope
Geology of the University of Aveiro (LGIUA).
The results obtained show that the
Sr isotopic variability of these waters is
strongly correlated with the age and
mineralogical composition of the aquifer
source rocks.
The lowest 87Sr/86Sr ratios are found in
water samples from the Monchique
aquifer (87Sr/86Sr = 0,70447), located in
Late Cretaceous alkaline magmatic rocks
of mantle origin. The Vimeiro waters are
hosted in carbonate and evaporite
formations of Jurassic age and have
87Sr/86Sr values of 0,70808, whereas the
waters sourced in Cenozoic siliciclastic
sediments tend to exhibit higher 87Sr/86Sr
ratios, close to the rainwater value (São
Silvestre; 87Sr/86Sr = 0,71078). Finally, the
waters coming from granitic and/or
metamorphic terrains of the Iberian
Variscan basement (Vitalis, Luso,
Carvalhelhos, Fastio, Serra da Estrela)
display the most radiogenic Sr isotopic
signatures (87Sr/86Sr > 0,7136).
In the modern commercial context, the
differences encountered provide a
powerful tool for fingerprinting the
mineral water origin and may be used for
purposes of mineral water authentication.
The use of 87Sr/86Sr ratios may also be
extended to studies on the provenance of
some foods and beverages, taking into
account the influence of the geological /
pedological factor on the Sr isotopic
composition recorded by the plants