1. Ramkrishna Nirola*, Rupak Aryal **, Megharaj Mallavarapu*,
Florescence imaging of mine site metallophyte: a convenient measure of plant stress.
Ramkrishna Nirola*, Rupak Aryal **, Megharaj Mallavarapu*,
Simon Beecham** , Christopher Saint*
* Centre for Environmental Risk Assessment and Remediation (CERAR), University of South Australia, Mawson Lakes, SA 5095
** School of Natural and Built Environments, Division of Information Technology, Engineering and the Environment, University of South Australia, SA 5095, Australia.
Even after spending billions, the plants struggle to colonize the mined land area.
The rehabilitation technology (Figure 1) is the use of plants through microbiological, biochemical, and bio engineering knowledge to revive lands by encouraging interactions involving minerals, water, and energy, through the patterns of ecological succession (Vranjic et al., 2012).
Plant stress is important measure of success or failure of phytoremediation and florescence spectroscopy is used to determine stress.
Introduction
Figure 1: The process of
Phytoremediation Developed by authors.
Figure 2: Golden wattle growing in
the mine site. Pic:- 29/03/2015
Methodology
The sampling site : GPS of 34°20'50.10"S and 138°55'4.78"E, an abandoned copper mine at Kapunda, South Australia.
Spectroscopy: Plant powder (2gm each) mixed in 0.1-M NaOH making up to 50 ml final volume, shaken in end-over shaker for 48 hours, centrifuged at 4000x20 rpm, filtered using 0.45µm syringe, and finally extract diluted for relative comparison to determine UV of 0.1 value absorbance (Aryal et al. 2012).
Florescence
spectroscopy
ICP-MS
Plant parts
Wash, powder
Rhizosphere soil
CNS, ICP-OES
Results & Discussion
In the florescence diagram of leaf and stem, the peak is more prominent in neutral soil indicating a vigorous expression of plant organics in the tissue grown in near to normal PH soil (Figure 3).
In the stem EEM 5, the peak is spread further within the two excitation and emission values possibly due to the effect of nitrogen in soil at 35 mg kg-1 (Table 1).
Table 1:- Soil characteristics of the mine site with Cu deposition level in the above ground parts.
Plant sample Plot 1 2 3 4 5
Soil PH
6.3
5.6
6.1
4.4
6.8
Soil EC (µS)
1276
326
117
405
367
Soil TN (mg kg-1) 11 9 6 35
Soil TOC (mg kg-1)
498
100
290 40
130
Stem Cu (mg kg-1) 25 63 17 45
Leaf Cu (mg kg-1)
283
114 99
178
Fluorescence EEM-Parallel Factor Analysis
Soil pH ranged from 4.4(acidic) to 6.8 (slightly acidic) and electronic conductivity (EC) from 117 to 1276.
The total nitrogen (TN) and total organic carbon (TOC) were lowest in the acidic soils corresponding to the lower accumulation of Cu in stem (Table 1).
Fluorescence excitation emission matrix (EEM) analysis
EEM is a tool to record both absorbed and released energy by loosely bound electron in a molecule. The specific excitation and emission is the characteristics of particular fluoropore (chemical).
Leaf
Stem 1 2 3 4 5
Component 2 is dominant in leaf where as component 1 was dominant in stem
Component 1 and Component 2 have negative relationship in leaf but not in stem
Figure 3: EEM Spectra of golden wattle leaf and stem for each sample
Conclusions
Florescence spectroscopy is one of the possible methods to determine stress level of plants growing over the contaminated sites such as abandoned mines. The use of florescense imaging may be strategically crucial to implement rehabilitation projects smartly and sustainably saving considerable expenses.
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