Agromining is the chain of processes that allows the phytoextraction of economically valuable elements by selected hyperaccumulator plants, and subsequent processing of biomass to produce targeted metals or commercial compounds of high value. Although substantial unrealized opportunities exist for economic nickel (Ni) agromining in the tropics, this technology has remained relatively unexploited. This study investigated the soil chemistry of a newly established tropical 'metal farm' and elucidated the elemental accumulation in prospective species to be used in a viable large-scale tropical Ni agromining program on ultramafic soils in Sabah (Malaysia). We found that a major portion of the site (>90%) had high total Ni concentrations (>2000 µg g -1 ) in a shallow Eutric Cambisol Magnesic. This study also recorded high phytoavailable soil Ni concentrations in the field plot, which is a desired property of soils intended for commercial Ni agromining. Moreover, the average soil pH of the field (pH 6.4) is ideal for maximum Ni uptake in the local candidate species.We recorded low concentrations of Ca, K and P, indicating the need for an improved fertilizer regime in sustainable agromining. The extraordinary shoot Ni concentrations (>2 wt%), coupled with the high purity of the 'bio-ore' of Phyllanthus rufuschaneyi, confirm its high potential for economic Ni agromining. The success of our first field trial is critical to provide 'real-life' evidence of the value of large-scale tropical 'metal farming'. Research priorities include the need to intensify the search for candidate species, determine their agronomy, and to develop sustainable technologies to process the biomass to recover valuable products.

No abstract

Plants have developed a diversity of strategies to take up and store essential metals in order to colonize various types of soils including mineralized soils. Yet, our knowledge of the capacity of plant species to accumulate metals is still fragmentary across the plant kingdom. In this study, we have used the X-Ray Fluorescence technology to analyze metal concentration in a wide diversity of species of the Neotropical flora that was not extensively investigated so far. In total, we screened more than 11 000 specimens representing about 5000 species from herbaria in Paris and Cuba. Our study provides a large overview of the accumulation of metals such as manganese, zinc and nickel in the Neotropical flora. We report 30 new nickel hyperaccumulating species from Cuba, including the first records in the families Connaraceae, Melastomataceae, Polygonaceae, Santalaceae and Urticaceae. We also identified the first species from this region of the world that can be considered as manganese hyperaccumulators in the genera Lomatia (Proteaceae), Calycogonium (Melastomataceae), Ilex (Aquifoliaceae), Morella (Myricaceae) and Pimenta (Myrtaceae). Finally, we report the first zinc hyperaccumulator, Rinorea multivenosa (Violaceae), from the Amazonas region. The identification of species able to accumulate high amounts of metals will become instrumental to support the development of phytotechnologies in order to limit the impact of soil metal pollution in this region of the world.

No abstract