Rare Earth Elements Characterization in Phosphate Fertilizers Marketed in Brazil.

Rare Earth Elements Characterization in Phosphate Fertilizers Marketed In Brazil GUILHERME SOARES DINALI; CRISTIANO GONÇALVES MOREIRA; FÁBIO HENRIQUE ALVES BISPO; CAMILLA BATISTA DE OLIVEIRA; CARLOS ALBERTO PÉREZ; TEOTONIO SOARES DE CARVALHO; SILVIO JUNIO RAMOS; JOSÉ OSWALDO SIQUEIRA; LUIZ ROBERTO GUIMARÃES GUILHERME Rare earth elements (REE) are a group of 17 chemical elements commonly found in phosphate fertilizers in a range of concentrations. Due to this, they are added to agricultural land, often involuntarily. A few studies have reported total REE levels in fertilizers, but information on REE­ mineral phases, as well as solubility in extractants that mimic plant available REE derived from P fertilizers is still scarce. This study aimed to characterize quantitatively and qualitatively REE in phosphate fertilizers marketed in Brazil. Quantitative analyses were performed using X-Ray fluorescence to determine the total REE content and also the soluble levels of REE in different extractants (water, neutral ammonium citrate - NAC -, and citric acid - CA). The mineralogical characterization was made using X-­Ray diffraction. Both characterizations were performed using synchrotron radiation at the National Synchrotron Light Laboratory in Campinas, Brazil. We have observed not only a great diversity in terms of mineral phases carrying REE (e.g. Britholite, Tritomite and Belovite as the main phases), but also different solubilities of Light-REE in phosphate fertilizers (varying from an average solubility of 5.8% in water, 14.4% in NAC, and 29.4% in CA), which in turn will cause a differential release of REE from P fertilizers to agroecosystems.