Elemental and Sr-isotope characterization of the high-altitude Bosa vineyard in the Apuan Alps UNESCO Global Geopark (Italy)

The Sr-isotope systematics and trace element analysis wereapplied to vine and wine collected during the 2015 harvest fromthe Bosa vineyard, a high-altitude farm in the Apuan Alps UNESCOGlobal Geopark in Italy, in order to investigate the links with geologyin vineyards facing with a hostile environment. The results indicatea correspondence between the 87Sr/86Sr ratio in wine and must[87Sr/86Sr = 0.70843(1) and 0.70846(1), respectively] and the NH4OAcextractable Sr from soil [87Sr/86Sr = 0.70847(1)]. However, detailedinvestigations reveal that Sr-isotope data on grape juice collected indifferent vines vary in the range between 0.70833(1) and 0.70844(1),reflecting a small-scale vineyard variability and indicating thatthe root system explores heterogeneous soil resources for nutrientuptake. Grape seeds and stems from one single vine both showidentical 87Sr/86Sr of 0.70820(1), significantly lower with respect tocorresponding juice [87Sr/86Sr=0.70844(1)]: this finding is unexpectedand reflects the uptake from isotopically different reservoir duringthe evolved dynamic of vine and fruit development. In particular,the lower 87Sr/86Sr ratio is attributed to the minor contribution of anunradiogenic carbonate component. These effects, however, do notmask the existing isotopic relationship between soil and wine at thevineyard scale. Trace elements in wine show a characteristic patternthat roughly mimics bedrock, suggesting a minor role of bedrockchemical weathering in developing the soil profile. Relatively high Feand Mn contents are measured in wine, inherited from bedrocks, andhigh Zn, possibly applied to grapevines. Elements that are consideredpotentially toxic (As, Cd, Cu, Pb, Zn) are below the maximumacceptable limits established by OIV.Despite preliminary, these data represent the first characterizationfor traceability of the high-altitude Bosa vineyard, giving some trackof weathering and elemental availability in a particular microclimatesetting and underlying the link between bedrock geology and elementuptake in vines at high elevations with respect to valley grown grapes.