Geochemical behaviour of rare earths in Vitis vinifera grafted onto different rootstocks and growing on several soils

摘要

The geochemical behaviour of lanthanides and yttrium(Rare Earth Elements, REEs) has been investigatedmainlyudin geological systems where these elements represent the best proxies of processes involving the occurrence ofudan interface between different media. This behaviour is assessed according to features recorded in sequences ofudREE concentrations along the REE series normalised with respect to a reference material. In this study, theudgeochemical behaviour of REE was investigated in different parts of Vitis vinifera specimens grown off-soil, onudsoils of different nature and grafted onto several rootstocks in order to evaluate effects induced by these changes.udThe results indicated that roots are the plant organs where REEs are preferentially concentrated, in particularudelements from Sm to Ho (middle REE, MREE) whereas Eu enrichments occur in aerial parts. The geochemicaludbehaviour of REE suggests that MREE enrichments in roots are due to preferential MREE interactions withudbiological membranes or to surface complexation with newly formed phosphates. Eu-positive anomalies suggestudthat Eu3+ can form stable organic complexes in place of Ca2+ in several biological processes in xylem fluids.udThe possibility that Eu mobility in these fluids can be enhanced by its reductive speciation as Eu2+ cannot beudruled out.udThe assessment of the geochemical behaviour of REE according to the theory of the Tetrad Effect carried outudconfirms that REEs coming fromsoil are scavenged onto root tissues or mineral surfaceswhereas their behaviourudin aerial parts of V. vinifera is driven by dissolved complexation.