Spatial distribution of mercury and gold in roots of cassava (Manihot esculenta) by micro-PIXE
Hannah Joy P Alcantara
University of Melbourne, Australia
University of the Philippines Diliman, Philippines
: J Plant Physiol Pathol
Abstract
Removal of mercury (Hg) by plant species offer new options to clean up Hg-contaminated sites and at the same time harvest gold (Au). Localization of Hg and Au in root tissues of a potential phytoremediator, cassava (Manihot esculenta), was investigated by micro-proton induced X-ray emission (micro-PIXE) spectrometry to gain a better understanding of Hg and Au uptake. Cassava cuttings were grown in a hydroponic culture for one week under controlled conditions and then exposed to different concentrations of Hg and Au solutions for six days. Qualitative elemental micro-PIXE analysis revealed that Hg was found all over the root cross-section but mainly localized in the endodermis and the root vascular bundle, for both low (50 μM Hg) and high (100 μM Hg) Hg treatments. The same is true for both the low-Au (50 μM Au) and high-Au (100 μM Au) treatment, with less localizations of Au in the former. Interestingly, plant exposure to equimolar concentrations of Hg and Au (50 μM Hg+50 μM Au) revealed both elements to be localized only in the epidermis, which was not the case when the plants were exposed to either Hg or Au alone. This suggests a plausible uptake competition between the two metals. Lastly, in the treatment where the Hg concentration is increased relative to the Au concentration (100 μM Hg+50 μM Au), Au was found to be strongly localized in the epidermis while Hg was found in all parts of the plant tissue, further confirming the hypothesis the Hg and Au could possibly be competing for uptake at the epidermal level.
Biography
Email: hannahdyoi@gmail.com
