Identification of hyperaccumulator plants in nickel mining leases: conservation strategies and potential applications 1
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A van der Ent* , D Mulligan and P Erskine 1
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Centre for Mined Land Rehabilitation, Sustainable Minerals Institute, The University of Queensland, Australia.
*Corresponding author:
[email protected], Centre for Mined Land Rehabilitation, The University of Queensland, St Lucia QLD 4072, Australia. Introduction Nickel hyperaccumulator (plants with more than 1000 mg/kg of nickel in their leaves) number approximately 450 species globally, mostly described from Cuba and New Caledonia (1). Nickel hyperaccumulator plants can contain 2-6% of nickel in their leaves and up to 25% in their latex or phloem sap (1). In tropical regions nickel hyperaccumulation occurs especially in the Buxaceae, Phyllanthaceae, Salicaceae and Rubiaceae families. The majority of nickel hyperaccumulator plants have narrow ranges, frequently endemic to single ultramafic outcrops. Ultramafic soils can host economically important (laterite) nickel reserves, which impose a threat from the minerals industry because extracting nickel from such deposits is destructive for occurring plants (2). Timely identification of hyperaccumulator plants occurring in nickel mining leases is hence necessary to facilitate their conservation and potential utilization in phytomining (a novel technology to extract nickel). Methods As part of a study on plant diversity of ultramafic outcrops in Kinabalu Park in Sabah (Malaysia) plants were screened for nickel hyperaccumulation using test paper impregnated with dimethylglyoxime (‘DMG’). Approximately 5000 plant samples have been tested using this method and all samples that tested positive were re-collected and analysed with ICP-AES in the laboratory in Australia. This methodology provides a model for the approach to be used on nickel mining leases in the Asia-Pacific Region. Results and Conclusions The documentation of 24 new nickel hyperaccumulator plant species from a relatively small area in Sabah (Malaysia) has underlined the potential for discovery if systematic screening is undertaken, particularly in the Asia-Pacific Region. Ongoing studies also reveal specificity to particular soils (shallow soils derived from serpentinite), which might have implications for predicting the distribution of hyperaccumulator plants, and for selecting soils potentially suitable for phytomining. Rather than viewing mining as an industry that can contribute to the destruction of populations of rare plants including hyperaccumulator plants, an offsetting perspective could be to use such biological resources in the subsequent rehabilitation to secure their survival. However, to be successful systematic screening before mining activities take place is essential. Further, gathering information about the reproductive ecology, methods of propagation and performance in culture is critical for using these species in rehabilitation and in phytomining applications. References (1) Van der Ent, A., Baker, A. J., Reeves, R. D., Pollard, A. J., & Schat, H. (2013). Hyperaccumulators of metal and metalloid trace elements: facts and fiction. Plant and Soil, 362(1-2), 319–334. (2) Van der Ent, A., Baker, A. J. M., van Balgooy, M. M. J., & Tjoa, A. (2013). Ultramafic nickel laterites in Indonesia (Sulawesi, Halmahera): Mining, nickel hyperaccumulators and opportunities for phytomining. Journal of Geochemical Exploration, 128, 72–79.
