Arsenic hyperaccumulation and localization in the pinnule and stipe tissues of the gold-dust fern (Pityrogramma calomelanos (L.) Link var. austroamericana (Domin) Farw.) using quantitative micro-PIXE spectroscopy |
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Authors: | Anthony G Kachenko Naveen P Bhatia Balwant Singh Rainer Siegele |
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Institution: | (1) Faculty of Agriculture, Food and Natural Resources, The University of Sydney, Sydney, New South Wales, 2006, Australia;(2) Institute for Environmental Research, Australian Nuclear Science and Technology Organisation, Lucas Heights, Sydney, New South Wales, 2234, Australia |
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Abstract: | Spatial distribution patterns of arsenic (As) in the tissues of a lesser-known As hyperaccumulating fern Pityrogramma calomelanos (L.) Link var. austroamericana (Domin) Farw. (Pteridaceae) have been studied. Quantitative micro-proton-induced X-ray emission (micro-PIXE) spectroscopy
was employed to examine As localization in pinnule and stipe cross-sections of this species. In addition, As hyperaccumulation
status of P. calomelanos var. austroamericana was compared with the well-known As hyperaccumulating fern Pteris vittata L. Both species were grown in pots under controlled conditions and exposed to four levels of As (0–500 mg As kg−1) for 20 weeks. Pityrogramma calomelanos var. austroamericana accumulated up to 16 415 mg As kg−1 dry weight (DW), however, phytotoxicity symptoms such as necrotic pinnule tips and margins, appeared in fronds with concentrations
>3,008 mg As kg−1 DW. Arsenic was readily translocated to fronds, with concentrations up to 75 times greater in fronds than in roots. Quantitative
elemental maps of As generated using micro-PIXE analysis revealed that As concentrations in pinnule cross-sections were higher
than in stipe cross-sections with concentrations of 3.7 × 103 and 1.6 × 103 mg As kg−1 DW, respectively (as determined by region selection analysis; RSA). In pinnules, RSA revealed variable concentrations of
As, however did not resolve a clear pattern of compartmentalization across different anatomical regions. In stipe tissues,
As concentrations followed the order vascular bundle > cortex > epidermis (as determined by RSA). Our results show that P. calomelanos var. austroamericana is an As hyperaccumulator and has the potential for use in phytoremediation of soils with low levels (up to 50 mg kg−1) of As contamination. |
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Keywords: | Arsenic (As) Hyperaccumulation Nuclear microprobe Pteris vittata L Sequestration X-ray microanalysis |
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