The potential of wild plants for phytoremediation of soil contaminated with mercury of gold cyanidation tailings

Abstract

In artisanal and small-scale gold mine (ASGM) area of West Lombok, Indonesia, gold is recovered through a two-stage process of amalgamation and cyanidation. Tailing is discharged to land with no concern for contaminants in the tailings. Phytoremediation could cost-effectively replace traditional mercury remediation strategies. The objective of this study was to investigate the potential of six wild plant species (Lindernia crustacea (L.) F., Digitaria radicosa Miq., Zingiber purpurium Roxb., Paspalum conjugatum L., Cyperus kyllingia Endl., and Caladium bicolor L.) for phytoremediation of soil contaminated with mercury of gold cyanidation tailings. This study was conducted in a shade house located nearby a cyanidation processing facility of ASGM at Sekotong Distrik of West Lombok. Samples of tailings-uncontaminated soil were mixed with samples of cyanidation tailings with the proportion of 30%: 70% (w/w). Each of the six plant seedlings was planted in a plastic pot containing 15 kg of soil-tailings mixture. At harvest (9 weeks), shoots and roots were analyzed for mercury concentration In general, the results indicated that none of the plant species were identified as hyperaccumulator. Based on BCFs, TFs, and BAC, L.crustacea, D.radicosa, P. conjugatum and C. kyllingia can be used for phytoextraction of Hg since they were efficient to take up and translocate mercury from roots to shoots. On the other hand, Z. purpureum and C. bicolor can be used for phytostabilization of mercury.