Optimization of Plant Species and Chelating Agents in Phytoextraction of Gold from Small-Scale Gold Mine Tailings

摘要

The disposal of small-scale gold mine tailings into agricultural land has caused a decline in crop productionin the District of Sekotong, Lombok Regency of Indonesia. One of the technologies that can be developedfor remediation of soil contaminated by small-scale gold mine tailings is phytoextraction. This study wasconducted in two steps. The first step was aimed to study the effect of various doses of fertilizer and soilamendment on the production of biomass of two plant species studied previously, i.e. Paspalum conjugatumand Cyperus kyllingia. Each seedling of the two plant species was grown for 9 weeks on the tailing disposaldam in a 1 × 1 m plot. Treatments tested were (1) plant species (two species), and (2) dose of NPK fertilizer(50, 100, and 150 kg/ha), and (3) dose of organic matter (5, 10, and 15 t/ha). The second step was to studythe effect of the type and dose of chelating agents on the best plant species resulted from the first step ofthis study. The treatments tested consisted of three types of chelating agent (ammonium thiosulphate,sodium thiosulphate and sodium cyanide) and three doses of each chelating agent (1, 1.5, 2 g/kg). At thetime of harvest (9 weeks), shoot and root of each plant were separated for the analysis of Au accumulation.The results showed that type of plant, dose of organic matter, and optimal applied fertilizer that generated thehighest growth and biomass production of the accumulator plants was a combination of P. conjugatum, 10kg NPK fertilizer/ha, and 10 t organic matter/ha. The type and dose of chelating agents applied to thecombined treatment affected Au accumulation. The best combination of type and dose of chelating agentwas 2 g of ammonium thiosulphate /ha. Overall, the combination of plant species, fertilizer dose, organicmatter dose, type of chelating agent, and dose of chelating agent was P. conjugatum with 100 kg NPKfertilizer/ha, 10 t organic matter/ha and 2 g ammonium thiosulphate/kg.