University of Natural Resources and Life Sciences, Vienna (BOKU) - Research portal
Gewählte Master / Diploma Thesis:
Christoph Höfer
(2013):
Trace metal solubility and bio-availability changes in the rhiziosphere of Salix smithiana in response to elemental sulfur amendments.
Master / Diploma Thesis - Institut für Bodenforschung (IBF),
BOKU-Universität für Bodenkultur,
pp 58.
UB BOKU
obvsg
FullText
- Abstract:
- The purpose of phytoextraction is to transfer trace metals (TMs) from polluted soils to plant shoot tissues, supported by the interaction of plants roots and microbial communities in the rhizosphere. Soil amendments and rhizosphere processes can increase TM bioavailability and flux in the soil. Here, we investigate the effects of elemental sulfur (S0) application on TM bioavailability in the rhizosphere of Salix smithiana, in a moderately Zn, Cd and Pb contaminated soil (ARNB-10) from Arnoldstein, Austria. Chemical and microbial sulfur oxidation acidifies the soil locally and decreases pH in the soil solution, which leads to enhanced metal solubilisation. Our focus was to investigate potential co-dissolution processes and other solubilisation mechanisms triggered by the S0-amendments. A rhizobox experiment was conducted using a ARNB-10 and two amounts of S0-amendments (HS=0.51 g kg-1; S=1.02 g kg-1). We sampled soil pore water eight times in the rhizosphere and bulk soil using Rhizon samplers over a period of 61 days. Samples were analyzed for pH, anions by Ion chromatography (IC), and TMs by Inductively coupled plasma mass spectrometry (ICP-MS). Willows were harvested, separated in roots, twigs and leaves, digested and analyzed (ICP-MS). For estimating potentially labile fractions in the soil, 0.05M Ca(NO3)2 extracts were measured for TMs using (ICP-MS). Results show decreased pH in both S0 treatments, whereas Mn, Zn, Cd and Pb solubility strongly increased. The S0-amended rhizosphere compartments showed significantly (p<0.05) larger increase in metal solubility than the corresponding bulk soils. Our data indicate that partially anaerobic conditions triggered by S0-oxidation and further enhanced by O2 depletion due to root respiration in the willow rhizosphere resulted in reductive co-dissolution of TMs associated with hydrous oxides of Mn. This process may be further explored for optimizing S-aided phytoextraction of Zn and Cd polluted soils.
- Beurteilende*r: Wenzel Walter