1. The green and gold in abandoned mines.
Ramkrishna Nirola
Future Industries Institute.
Abstract
Acacia pycnantha with five blue arrows indicating experimental analysis of phytoaccumulation and plant stress including soil characterization
Study site
Fig.1. Sampling plots at the Kapunda mines, South Australia
Fig.2 Changes in pore water dynamics and biochemical attributes.
A: The pore water metal dynamics showing prominent As, Pb and Cu activity.
B: Response of proline and chlorophyll over time on metal polluted soil.
[X-Axis:- Chl-A (mg g-1 tissue) and Chl-B (mg g-1 tissue), Z-Axis:- β Carotene (mg g-1 tissue), soil Cu (mg kg-1) and proline (µg g-1 tissue].
Introduction
Semi-arid and arid mines are typically difficult to revegetate (Johnson & Putwain, 1981). However, we earlier reported the Australian golden wattle as a copper stabilizer in abandoned copper (Cu) mine soils (Nirola et al., 2015a&b).
Here we report our further research on this investigation to confirm this plant’s suitability to grow on metal contaminated mine soils.
Golden wattle was grown under greenhouse condition in six different soils collected from abandoned copper mine at Kapunda in South Australia (Fig.1).
Among the six soils samples, soil-HC with the highest copper concentration produced 2.05 mmol proline g-1 tissue. Proline expression was prominent in more saline soils (HC, M and ECR) having EC 1184, 1364 and 1256 µS, respectively.  Chlorophyll a, b and carotenoid levels in plants showed a gradually decreasing trend in all the soils as experiment progressed (Fig. 2).
The plants grown on soil containing 4083±103 mg kg-1 of copper resulted in 18±2 mg kg-1 Cu accumulation in its leaf (Nirola et al., 2016). The calcium accumulation was significant up to 11648±1209 mg kg-1 in leaf.
The germination of seeds of A. pycnantha collected from mine area were tested after heat and no heat treatment on two types of irrigation. The daily irrigated and heat treated seeds gave up to 85% germination on sandy soil.
The pore water analysis showed a higher Cu concentration but an increased mobility of arsenic and lead with an increase in time period was observed in the soil. Our experiment using a single species of plant points out the need for proper monitoring of revegetation processes as most of the species are stressed which can lead to poor/failure of revegetation.
Results and Discussion
Conclusion
Our study on the growth of A. pycnantha on copper contaminated mine soils revealed this plant as a metal stabilizer. The study site had a uniform soil characteristics and this leguminous species showed resilience to adverse conditions due to low metal enrichment in its above ground parts. Its ability to tolerate salinity, acidity and low nutrition level of soils was evident through its germination and growth responses. This species with adequate watering could germinate and thrive on mine soils and thus could be recommended for revegetation in arid and semi-arid climatic zones. While this wattle species could exclude Cu uptake, the As and Cd seems to be toxic to it.
Acknowledgement
Supervisors: Mallavarapu Megharaj, Rupak Aryal, Christopher Saint, Simon Beecham, Thavamani Palanisami, Ravi Naidu.
Travel grant: Future Industries Institute (FII) and School of NBE , University of South Australia, Mawson Lakes SA 5095.
References
JOHNSON, M.S. & PUTWAIN, P.D., Restoration of native biotic communities on land disturbed by metalliferous mining. Minerals and the Environment, 3(3), pp
NIROLA, R., MEGHARAJ, M., ARYAL, R. & NAIDU, R. 2015a. Screening of metal uptake by plant colonizers growing on abandoned copper mine in Kapunda, South Australia. International journal of phytoremediation. doi: /
NIROLA, R., MEGHARAJ, M., PALANISAMI, T., ARYAL, R. & VENKATESWARLU, K. 2015b. Evaluation of interaction of major native-trees colonizing an abandoned copper mine soil with heavy metals; a quest for phytostabilization.
Journal of Sustainable Mining. doi: /j.jsm
NIROLA, R., MEGHARAJ, M., ARYAL, R. SAINT, C., BEECHAM,S., PALANISAMI, T., VENKATESWARLU, K. NAIDU,R Metal bioavailability to Eisenia fetida through abandoned mine plant and animal litter, a new challenge on contaminated environment remediation. International journal of biodegradation and bio deterioration. doi: /j.ibiod
Revegetation at Kapunda mine site-2015
Presented at: Mine Rehabilitation Conference, Singleton, NSW. 7th April By: Ramkrishna Nirola