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Gewählte Doctoral Thesis:

Muhammad Iqbal (2012): Changes in cadmium and zinc bioavailability by pH manipulation of soil, its assessment by soil extraction, DGT, indicator plants and consequent effects on phytoextraction with Salix smithiana.
Doctoral Thesis - Institut für Bodenforschung (IBF), BOKU-Universität für Bodenkultur, pp 77. UB BOKU obvsg

Data Source: ZID Abstracts

Abstract:: Phytoextraction is a plant-based in situ innovative and eco-friendly technology to remediate metal polluted soils. As the manipulation of soil pH affects the bioavailability of metals, phytoextraction efficiency can be improved by appropriate lowering of soil pH. This research aimed to evaluate the impact of decreasing soil pH on Cd and Zn bioavailability, resupply and their phytoextraction with S. smithiana. To this end, the effect of nitric acid addition on metal concentration in chemical indicators of bioavailability, DGT (diffusive gradients in thin films) parameters and metal concentrations in two indicator plant species were assessed. Also the impact of sulfur induced soil acidification on metal solubility and remobilization in soils which have been initially immobilized and their subsequent phytoextraction with Salix smithiana was tested. Decrease in soil pH increased metal concentrations in soil solution, in 5 mM Ca(NO3)2-solution and the DGT-measured Cd and Zn concentrations (CDGT) in the experimental soils. As a result enhanced uptake of Cd and Zn on soil pH level 4.5 was observed in both indicator plants. Decrease in metal resupply kinetics and metal toxicity suggests that moderate soil acidification is preferred over extreme acidification to enhance phytoextraction process. Soil solution pH, Cd and Zn concentration were as expected during the growth period of S. smithiana except enhanced metal solubility in the presence of both sulfur and willows which was magnified by reductive co-dissolution from Mn (IV) and Fe(III) (oxy)hydroxides during microbial S oxidation in the willow rhizosphere, resulting in enhanced phytoextraction by up to ~50%. Sulfur application on initially immobilised soils induced partial remobilization of Cd and Zn which seems practical as in the start it can control metal leaching to deeper layer and ground water and, later on, can enhance phytoextraction efficiency once the phytoextracting crop is sufficiently established.; Betreuer: Wenzel Walter; 1. Berater: Puschenreiter Markus; 2. Berater: