Interazioni tra il suolo, l’atmosfera, l’idrosfera e la vite. Indagine geochimico-isotopica

Abstract

In the wine world, isotopic analyses are carried out to verify the variation of these parameters depend on natural factors, i.e. soil-water-plant-atmosphere interactions. In water molecules of the grape berry the values of the isotope ratios 2H/1H and 18O/16O are linked to the characteristics of the water present in the soil and evaporation phenomena to which the leaves and the grape are subjected. The isotopic characteristics of the water assimilated by plants are, in turn, dependent on those of the precipitation waters, which are dependent on climatic factors. Therefore, the isotopic characteristics of the hydrogen and oxygen in the water of the grapes are the complex result of the water and the climate of the place where the plant grew (geological-geographical proxy). The isotopic composition of water in different parts of the vine is initially determined by the water absorbed from the soil since isotopic fractionation does not occur. Isotopic fractionation occurs gradually during the grapes ripen, as they are subject to climatic conditions. In turn, the isotope ratio of carbon in the organic part of the berry and, in general, in the different parts of the vine, is fundamentally linked to the biological fixation phenomenon that characterizes the plant, which is linked to climatic conditions. Additional indications regional scale can be given by the report isotope of strontium (87Sr/86Sr), which is linked to the lithological characteristics of the area in which the plant grows up. The relevance of the use of these isotopes is due to the fact that they do not fractionate. With regard to wine, the origin can be differentiated through the isotopic ratios measured on the water of the grape if the isotopic characteristics of the geological substrate on which the plant grows are known.