A ‘Geo-Pedo-Fingerprint’ (GPF) as a tracer to detect univocal parent material-to-wine production chain in high quality vineyard districts, Campi Flegrei (Southern Italy)

An interdisciplinary study, involving geologists, chemists and pedologists, started aiming at identifying a “Geo- Pedo-Fingerprint” (GPF) univocally linking the wine to its origin, namely, the Piedirosso vineyards growing in the Campi Flegrei volcanic area. The focal point of this research was the characterization of the whole parent material–soil–vineyard–wine system, achieved by correlating the elemental pattern – with special reference to micro-nutrients and Rare Earth Elements (REEs) – and Sr isotopic ratios, to identify a reliable and convenient ‘GPF‘, as a guaranteed indicator of wine provenance. A representative soil/Piedirosso vineyard system was identified and characterized. Samples from each soil horizon as well as from vine branches, leaves, grapes and wine were collected and analyzed. All samples were analyzed by multi-collector inductively coupled mass spectrometry (MC-ICPMS) to determine their 87Sr/86Sr isotopic composition, by ICP-Quadrupole MS to measure multielemental composition including REE, and by X-Ray Powder Diffraction (XRPD) for the quantitative evaluation of the mineral phases occurring in soil samples. Statistical analysis (Hierarchical Cluster Analysis, Factor Analysis) revealed the existence of separate correlations of element distribution between: i) soil, as nutrient pool source, and vegetative compartments, i.e. branches and leaves, as biochemical yards for nutrient elaboration and marshaling, ii) vegetative compartments and the productive compartment, i.e. grapes as the metabolic outcome of the vine, and, iii) the productive compartment and its artifact produced by man, i.e. wine. However, no sequential correlation of elements from soil to wine did appear, likely because clusters of elements were discriminated due to the varying take up and fractionation processes in plants, as well as during vinification processes. Therefore, none of the investigated elements was a liable ‘GPF’ as a candidate tracer from soil to wine. In contrast, the use of a petrogenetic tracer such as 87Sr/86Sr isotopic composition provided satisfactory responses. In fact, the values of such a ratio within the entire studied chain vary in a very small range from 0.7076 to 0.7084, thus falling within the typical range for volcanites of Campi Flegrei (0.7065–0.7086). These results currently represent the only study focusing on a geotracer, such as the 87Sr/86Sr isotopic ratio, linked with a pedological survey to identify the volcanic Campanian wine-producing chains from soil parent material-to-wine