Rhizosphere chemistry and above-ground elemental fractionation of nickel hyperaccumulator species from Weda Bay (Indonesia)

Aim: The identification and use of hyperaccumulator plants in mining projects has been recognized as an important component of mine planning at several sites around the world. The objective of this research was to provide information on relevant plant tissue chemistry and an indicative assessment of the potential for phytomining at Weda Bay Nickel (WBN), Halmahera. Methods: The first stage was the identification of native nickel hyperaccumulator plants. In total, 280 plant tissue samples from 10 nickel accumulator species and 46 matching rhizosphere soil samples were collected. Chemical analyses of plant tissue samples were performed and physico-chemical parameters of the rhizosphere soils were also measured. Results: A total of three species were considered as metal crops: Rinorea aff. bengalensis (up to 22,200 mg kg −1 dry weight at 2 m above ground level), Ficus trachypison (1060 mg kg −1 ) and Trichospermum morotaiense (5180 mg kg −1 ), but only R. aff. bengalensis has sufficiently high Ni concentrations in biomass to warrant field trials. Conclusions: Utilising a successional planting strategy, F. trachypison and T. morotaiense could be used to facilitate site conditions, followed by the metal crop R. aff. bengalensis. Using this design, a nickel yield of 330 kg per hectare would be possible every 4 years. In addition to allowing the recovery of nickel, this approach could be an integrated mine site rehabilitation strategy to mitigate environmental impacts, improve soil quality and facilitate transition to other land-uses such as native forest