Identifying the origin of rock phosphates and phosphorus fertilizers through high-precision measurement of the strontium isotopes 87Sr and 86Sr

This work presents a precise and accurate determination of R(87Sr/86Sr) by Thermal Ionization Mass Spectrometry (TIMS) to identify the origin of rock phosphates used for manufacturing of phosphorus (P) fertilizers. The Sr isotope ratios allowed to classify rock phosphate samples into four different groups: the first group includes igneous rock phosphates from Russia (Kola), the second group sedimentary rock phosphate samples from Algeria, Israel, Morocco, Tunisia and Syria, the third group sedimentary rock phosphates from the USA, while rock phosphate samples from Senegal and Togo are located in the last group. The R(87Sr/86Sr) isotope ratios in P fertilizers reflect the Sr isotopic composition of rock phosphates from which they were produced. Therefore Sr isotope ratios are suggested as a suitable indicator to track the origin of rock phosphates and P fertilizers.