TY  - JOUR
AU  - Sun, Y.
AU  - Amelung, W.
AU  - Wu, Bei
AU  - Haneklaus, S.
AU  - Maekawa, M.
AU  - Lücke, A.
AU  - Schnug, E.
AU  - Bol, R.
TI  - ‘Co-evolution’ of uranium concentration and oxygen stable isotope in phosphate rocks
JO  - Applied geochemistry
VL  - 114
SN  - 0883-2927
CY  - Amsterdam [u.a.]
PB  - Elsevier Science
M1  - FZJ-2020-03191
SP  - 104476 -
PY  - 2020
AB  - Phosphate rocks (PRs) used in fertilizer production contain uranium (U), which enters agricultural soils through phosphorus fertilization. However, our knowledge is still limited and cannot explain the different levels of U contamination found in agricultural systems. The paper reviewed the spatial and temporal U variations in PRs to obtain a comprehensive overview of U levels in various PRs worldwide and to investigate why U concentrations in igneous PRs are significantly lower compared to sedimentary PRs, and why less U is present in old sedimentary PRs (Precambrian-Cambrian) than in younger PRs (Ordovician-Neogene). In addition, the natural oxygen isotope compositions of phosphate (δ18Op) in various PRs were determined to identify their origins in relation to their U concentration. The δ18Op values differed among igneous PRs, old sedimentary PRs, and younger sedimentary PRs. Generally, the PRs with low δ18Op values had low U concentrations. In igneous PRs, low U concentrations were due to the lack of secondary U enrichment processes after rock formation, with low δ18Op values resulting from limited isotope fractionation at high temperature. Conversely, in sedimentary PRs, both U concentrations and δ18Op values were influenced by paleoclimate and paleogeographic features. Overall, there is a time-dependent coincidence of processes altering U concentration and δ18Op signatures of sedimentary PRs in a similar direction.
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000518403400002
DO  - DOI:10.1016/j.apgeochem.2019.104476
UR  - https://juser.fz-juelich.de/record/884305
ER  -