Mobility of fertiliser-derived uranium in arable soils and its contribution to uranium concentrations in groundwater and tap water

  • Phosphorus (P) mineral fertilisers are found to contain high concentrations of uranium (U) (up to 206 mg U kg-1) and other trace elements (TE), such as Cd, Pb, Ni, Cu, Zn, Th, Nb, Sr, V, and rare earth elements. The content of U and other trace elements is depended on the sedimentary of igneous origin of the rock phosphate. In this study, the production of P fertilisers has been shown to contaminate top soil horizons with U and other trace elements in the close vicinity of a factory located in Southern Brazil. In contrast to this point source, agricultural P fertilisation leads to a diffuse contamination of the agro-ecosystem with U and other fertiliser-derived trace elements on a large scale. Top soil horizons of arable land accumulate fertiliser-derived U. According to the geochemical behaviour of U(VI) species under oxidising conditions, the mobilisation capacity for U in top soil horizons is considered to be high, contrary to other fertiliser-derived heavy metals (e.g. Cd). Hence, it is assumed that U can be leached to shallow groundwater and can reach fresh water resources potentially used for drinking water supply. The aims of this study were to investigate the concentration of U and other contaminants in P fertilisers, to identify geochemical processes of fertiliser-derived U mobility and mobilisation from arable top soil horizons to the groundwater, and to evaluate the origin of U in German groundwater and tap water. This study presents the broadest recent data set on regional distribution of U concentrations in German tap water to which 76 % of the German population has access. The mean U concentration was 0.68 æg L-1, the median 0.50 æg L-1. 1.3 % or 1 million of the 80.6 million inhabitants in Germany are exposed to U concentrations in tap water which are higher than the German drinking water threshold limit of 10 æg L-1. The regional distribution of U concentrations largely agrees with the geological setting reported for mineral waters, however, in addition evidence for fertiliser-derived U in tap water was found in certain areas in Northern and Southern Germany. To test the hypothesized fertiliser-derived U leaching to groundwater, samples from different depths were taken in an area intensively used for cropping production in Lower Saxony. The correlation between fertiliser-derived nitrate (NO3-) and U especially in shallow (< 15 m) groundwater samples indicates the anthropogenic origin of U. However, there is not yet a clear picture of quantities and processes of U leaching from fertilised soil into groundwater. The future aim is to investigate these processes of U migration via isotope fingerprinting and geochemical modelling to provide a solid foundation for future risk assessment.

Download full text

Cite this publication

  • Export Bibtex
  • Export RIS

Citable URL (?):

Search for this publication

Search Google Scholar Search Catalog of German National Library Search OCLC WorldCat Search Catalog of GBV Common Library Network Search Catalog of Jacobs University Library Search Bielefeld Academic Search Engine
Meta data
Publishing Institution:IRC-Library, Information Resource Center der Jacobs University Bremen
Granting Institution:Jacobs Univ.
Author:Geerd Ahlrich Smidt
Referee:Andrea Koschinsky, Ewald Schnug, Michael Bau
Advisor:Andrea Koschinsky
Persistent Identifier (URN):urn:nbn:de:101:1-201305294841
Document Type:PhD Thesis
Language:English
Date of Successful Oral Defense:2012/12/11
Date of First Publication:2012/12/10
PhD Degree:Geosciences
School:SES School of Engineering and Science
Library of Congress Classification:G Geography. Anthropology. Recreation / GB Physical geography / GB651-2998 Hydrology. Water
Call No:Thesis 2011/64

$Rev: 13581 $