%0 Journal Article
%A Sun, Y.
%A Amelung, W.
%A Wu, Bei
%A Haneklaus, S.
%A Maekawa, M.
%A Lücke, A.
%A Schnug, E.
%A Bol, R.
%T ‘Co-evolution’ of uranium concentration and oxygen stable isotope in phosphate rocks
%J Applied geochemistry
%V 114
%@ 0883-2927
%C Amsterdam [u.a.]
%I Elsevier Science
%M FZJ-2020-03191
%P 104476 -
%D 2020
%X 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.
%F PUB:(DE-HGF)16
%9 Journal Article
%U <Go to ISI:>//WOS:000518403400002
%R 10.1016/j.apgeochem.2019.104476
%U https://juser.fz-juelich.de/record/884305