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| Titel |
Bioavailable concentrations of germanium and rare earth elements in soil as affected by low molecular weight organic acids and root exudates |
| VerfasserIn |
Oliver Wiche, Balázs Székely, Nicolai-Alexeji Kummer, Ute Heinemann, Silke Tesch, Hermann Heilmeier |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250091287
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| Publikation (Nr.) |
 EGU/EGU2014-5572.pdf |
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| Zusammenfassung |
| Availability of elements in soil to plant is generally dependent on the solubility and mobility
of elements in soil solution which is controlled by soil, elemental properties and plant-soil
interactions. Low molecular organic acids or other root exudates may increase mobility
and availability of certain elements for plants as an effect of lowering pH in the
rhizosphere and complexation. However, these processes take place in a larger volume in
soil, therefore to understand their nature, it is also important to know in which
layers of the soil what factors modify these processes. In this work the influence
of citric acid and root exudates of white lupin (Lupinus albus L.) on bioavailable
concentrations of germanium, lanthan, neodymium, gadolinium and erbium in soil solution
and uptake in root and shoot of rape (Brassica napus L.), comfrey (Symphytum
officinale L.), common millet (Panicum milliaceum L.) and oat (Avena sativa L.) was
investigated. Two different pot experiments were conducted: (1) the mentioned
plant species were treated with nutrient solutions containing various amount of
citric acid; (2) white lupin was cultivated in mixed culture (0 % lupin, 33 % lupin)
with oat (Avena sativa L.) and soil solution was obtained by plastic suction cups
placed at various depths. As a result, addition of citric acid significantly increased
germanium concentrations in plant tissue of comfrey and rape and increased translocation
of germanium, lanthan, neodymium, gadolinium and erbium from root to shoot.
The cultivation of white lupin in mixed culture with oat led to significantly higher
concentrations of germanium and increasing concentrations of lanthan, neodymium,
gadolinium and erbium in soil solution and aboveground plant tissue. In these pots
concentrations of citric acid in soil solution were significantly higher than in the
control.
The results show, that low molecular organic acids exuded by plant roots are of great
importance for the mobilization of germanium, lanthan, neodymium, gadolinium and erbium
in the rhizosphere and therefore the enhancement of bioavailability of the mentioned
elements to plants. Based on the suction cup experiment we conclude that in vertical soil
profile the bioavailable germanium is heavily affected by the activity of exudates, as the
complexation processes of germanium take place at the root zone and below affected by
the interplay of the infiltration of citric acid solutions and the actually produced
exudates.
These studies have been carried out in the framework of the PhytoGerm project, financed
by the Federal Ministry of Education and Research, Germany. BS contributed as an
Alexander von Humboldt Research Fellow. The authors are grateful to students
and laboratory assistants contributing in the field work and sample preparation. |
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