Effects of citric acid and the siderophore desferrioxamine B (DFO-B) on the mobility of germanium and rare earth elements in soil and uptake in Phalaris arundinacea

ABSTRACT

Effects of citric acid and desferrioxamine B (DFO-B) on the availability of Ge and selected rare earth elements (REEs) (La, Nd, Gd, Er) to Phalaris arundinacea were investigated. A soil dissolution experiment was conducted to elucidate the effect of citric acid and DFO-B at different concentrations (1 and 10 mmol L⁻¹ citric acid) on the release of Ge and REEs from soil. In a greenhouse, plants of P. arundinacea were cultivated on soil and on sand cultures to investigate the effects of citric acid and DFO-B on the uptake of Ge and REEs by the plants. Addition of 10 mmol L⁻¹ citric acid significantly enhanced desorption of Ge and REEs from soil and uptake into soil-grown plants. Applying DFO-B enhanced the dissolution and the uptake of REEs, while no effect on Ge was observed. In sand cultures, the presence of citric acid and DFO-B significantly decreased the uptake of Ge and REEs, indicating a discrimination of the formed complexes during uptake. This study clearly indicates that citric acid and the microbial siderophore DFO-B may enhance phytoextraction of Ge and REEs due to the formation of soluble complexes that increase the migration of elements in the rhizosphere.

KEYWORDS:

• phytoextraction
• citric acid
• desferrioxamine B
• Phalaris arundinacea
• germanium
• rare earth elements

Acknowledgments

The authors are indebted to numerous students who were involved in the experiments, for their activity. The authors are grateful to Helmut Bimberg for the technical support.

Funding

These studies have been carried out in the framework of the PhytoGerm project financed by the Federal Ministry of Education and Research, Germany (Grant Number 033R091A). DT was supported by a grant of the Federal Ministry of Education and Research and Projektträger Jülich (033R147).