Judul: Identification of Potential Phytoaccumulator Plants as a Gold (Au) Phytomining Agent
Abstrak: 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)
Keyword: phytoaccumulator, gold phytomining, tailings dam, Typha angustifolia

Judul: Physiological Respond of Duckweed Plants During Gold Mining Tailing Medium Treatment for Phytomining Purpose
Abstrak: Limbah tambang emas (tailing) meskipun mengandung banyak logam berat, masih mengandung emas dalam jumlah kecil. Fitomining merupakan metode ramah lingkungan yang dapat dilakukan untuk mengekstrak emas dari bahan berkonsentrasi emas rendah. Tujuan penelitian ini mengukur respon fisiologis tumbuhan mata lele yang ditumbuhkan pada media tailing tambang emas dan kemampuannya untuk mengakumulasi emas. Tumbuhan mata lele (Landoltia punctata dan Lemna aequinoctialis) ditumbuhkan selama 7 hari pada media Hogland mengandung tailing 0, 4, 10, dan 20% serta media mengandung emas 138 ppm. Parameter fisiologis tumbuhan dan akumulasi emas diukur setelah semua perlakuan diberikan. Hasil yang didapatkan, perlakuan tailing memicu respon cekaman oksidatif yang ditandai dengan penurunan kadar pigmen fotosintesis dan pembentukan H2O2 serta malondialdehid pada kedua tumbuhan. Cekaman oksidatif tersebut memicu perubahan kadar antioksidan seperti penurunan kadar fenolik dan flavonoid total. Cekaman osmotik juga terjadi pada tumbuhan tersebut, ditandai dengan peningkatan kadar gula pereduksi dan prolin. Kadar emas terbanyak yang berhasil diakumulasi L. punctata dan L. aequinoctialis dari tailing berturut 1,8 dan 1,5 µg g-1, sedangkan pada larutan HAuCl4 0,7 mM terakumulasi berturut hingga 24,7 dan 19,8 mg g-1. Berdasarkan hasil tersebut, tumbuhan mata lele mengalami cekaman oksidatif dan osmotik selama perlakuan fitomining namun tetap dapat mengakumulasi emas dari tailing tambang emas., Despite containing heavy metals, gold mine waste (tailing) still contains a small amount of gold. Phytomining is an environmentally friendly method that can be used to extract gold from tailings. The objective of the research was to observe physiological responses of duckweeds grown on gold mine tailing for phytomining purposes. Duckweeds (Landoltia punctata and Lemna aequinoctialis) were grown for 7 days in Hoagland’s medium that contained tailing of 0, 4, 10, and 20%, while gold 138 ppm solution as a positive control. Physiological parameters and gold accumulation were measured after treatments. The results, showed that tailing caused oxidative stress, indicated by a decrease in photosynthetic pigments level and formation of H2O2 as well as malondialdehyde. Oxidative stress triggered changes in antioxidant levels, indicated by a decrease in total phenolic and flavonoid. Osmotic stress occurred in both species characterized by increased levels of reducing sugars and proline. L. punctata and L. aequinoctialis were able to accumulate gold from the tailings up to 1.8 and 1.5 µg g-1, respectively, while in gold solution they accumulated 24.7 and 19.8 mg g-1, respectively. The research concludes that the duckweed undergoes oxidative and osmotic stress during phytomining, but able to accumulate gold from the tailing.
Keyword: Aqua regia, bio-ore, hyperaccumulator, phytoremediation, precious metal

Judul: Penyelesaian Masalah Rotasi Aliran Fluida Kental Von Karman Menggunakan Metode Homotopi
Abstrak: Von Karman equation is an equation that describes fluid viscous flow induced by infinite disk rotation. By assuming steady flow and laminar, viscous incompressible fluid flow is represented in Von Karman equation by an angular velocity and the vertical direction velocity as the independent variables. Von Karman equation is a nonlinear problem that is solved using the homotopy method. The use of homotopy method is done by defining an homotopy function that requires auxiliary parameters to control the convergent region of the solution. The solution is a recursive formula with given initial conditions. Using software based-functional shows that velocity components converge to a value.
Keyword: