Identifikasi Tumbuhan Fitoakumulator yang Berpotensi Sebagai Agen Fitomining Emas

Abstract

Indonesia is a tropical country which has a high diversity of plant species. It is estimated that many types of plants that exist in Indonesia have the potential as phytoaccumulators that may be able to absorb metals. This potential can be used for genetic resources pool that have special uses for phytomining. Phytomining is the process of extracting certain metals from soils with high metal content or contaminated with metals using certain plants for commercial purposes. The expected plants should be able to absorb certain metals in high amounts (hyperaccumulators) with a relatively short period. For more effective reason, the plants should also be local plants grown around the metal-contaminated location. Phytomining also has the potential to be applied by mining industry to provide economic benefits. The research was conducted from November 2019-October 2020. The plants and gold tailings waste were collected from the area around tailings dam in PT ANTAM UBPE in Pongkor, Nanggung District, Bogor Regency. The line transect method was applied to retrieve plant samples. The measured parameters were including the number of individuals, habitus, important value index (IVI), and species diversity index (H’). The gold (Au) concentration analysis in the plant shoots and roots and in the tailings mud/sediment was carried out in the Laboratory of Hydrochemical, Research Center for Limnology-National Research and Innovation Agency. During the experiment, plant growth analysis was done by measuring the shoots length, the roots length, the shoots dry weight and the roots dry weight. The analysis of lipid peroxidation was also carried out by measuring the levels of malondialdehyde (MDA). This morphological and physiological analysis was carried out at the Plants Physiology and Genetics Laboratory, Department of Biology, IPB University. The results of the vegetation analysis found a total of 17 species from 9 families with total number of plants was 1014 individuals. The habitus inventory was dominated by understory plants (herbs, shrubs, lianas), and herbs were the most dominant. The highest IVI value was obtained by T. angustifolia, C. compactus, and L. hexandra with the values of 46.14, 30.27, and 27.30, respectively. This indicated that these plants had important role in the study area. Meanwhile, the species diversity index (H') in the study area was 2.01 (1 ≤ H’≤ 3), which indicates that the diversity index was categorized as moderate. The analysis results of shoots MDA levels from 17 species obtained that Amarantus sp. and M. cordata had the highest MDA content (MDA > 1) i.e.: 1.95 mol/g and 1.25 mol/g, respectively, suggesting that the two species were experiencing higher metal stress. Based on the growth parameters, T. angustifolia had the highest shoots length (190 cm), while E. indica had the highest roots length (18.5 cm) when compared to other species. The highest shoots dry weight was found in T. angustifolia species, while the highest roots dry weight was found in E. indica species. All the 17 plant species that were found were able to accumulate gold (Au) metal residues from gold tailings waste, although with distinct concentrations among the species. Amaranthus sp. had the highest total average of gold (Au) concentration i.e.: 667.5 µg/kg dry weight. In contrast, P. polystachion had the lowest gold (Au) concentration average i.e.: 478.9 µg/kg dry weight. Based on the gold distribution, about 10 species had higher gold (Au) concentration in the shoots than that in the roots. The plant species with the highest bioconcentrafion factor (BCF) value was Amaranthus sp. (0.0374), and the plant species with the lowest BCF value was P. polystachion (0.0203). The plant species with the highest translocation factor (TF) value was M. cordata, while the plant species with the lowest TF value was F. miliaceae. The TF value obtained indicates that most of the plants (60%) found at the tailings dump location had a phytoextraction mechanism. The results showed that the highest potential of phytomining (PP) Au metal were T. angustifolia (2.8636 g/hectare Au dry weight) and C. haspan (2.8560 g/hectare Au dry weight). It can be concluded that T. angustifolia and C. haspan are the most prospective plants and potential candidates as gold metal phytoaccumulators.