Analysis of geochemical tracers in different systems soil-Citrus limon (L.) Osbeck

Today is increasing the attention of consumers for the origin of food and high reputation of products with a distinct geographical identity. Food traceability is an important issue in food safety and quality control, with impacts on food security, its quantity and overall availability. The knowledge of a chemistry relationship between the soil and the agricultural products is an important tool for the quality assessment of food. Citrus Limon is the most important fruit tree crop in the world and the detection of potential fraud could improve by using tools linking the chemistry composition of this production to its typical growing area. This study use rare earth elements (REEs) as geochemical tracers. The REEs are a set of 14 elements, from lanthanum to lutetium that can be divided in light rare earth elements (LREEs), from La to Gd and heavy rare earth elements (HREEs), from Tb to Lu. The REEs have recognized as very useful tracers due to their generally coherent and predictable behavior. The aim of the research is to observe whether the fruits of various cultivars of citrus cultivated on the same soil and their products (fruit and juice) reproduce the same distribution of REEs. Taking into account of our previous works carried out on grapevine – soil system [1, 2], we applied the same technique to evaluate and trace the REEs distribution in soil– Citrus Limon fruits system. Ten different varieties of Lemon fruits (Citrus limon Osbeck (L.)) were sampled. Lemon plant were grafted onto an unique rootstock (Citrus × aurantium L.), grown on volcanic soil in two experimental farms, located at the "Acireale" region (latitude 37 ° 37'23 N, longitude 15° 09'51.00 E and 205 m a.s.l., in Sicily, Italy) and “Portici” region (latitude 40 ° 81' 55 N, longitude 14° 34'75.00 E and 75 m a.s.l., in Campania, Italy). The varieties selected were: Akragas, Erice, Selinunte, Segesta, Continella, Femminello Siracusano, Femminello Dosaco, Kamarina, Sfusato, Ovale di Sorrento, Interdonato. A sample of 2 kg of fruit was collected at technological ripeness from each plant of three for every cultivar. As well as, three soil samples (about 2 kg) in the field corresponding to lemon sampling were collected and to reduce any surface contamination from a depth of 10–30 cm. The REEs amount, the HREEs/LREEs relations and their distribution in the fruit and citrus juice with respect to the own soil were determined and calculated. Results obtained were treated with statistical methods. The intriguing results obtained with a geochemical approach are the first on the soil–Citrus Limon fruits system.