Phytoremediation of Heavy Metals and Hydrocarbons from Spiked and Abandoned Landfill Soils by Polyscias fruticosa and Acalypha wilkesiana Plants

Phytoremediation is a plant-based remediation process for treating contaminated soils. The overall aim of this project was to determine the potential of Polyscias fruticosa and Acalypha wilkesiana for the phytoextraction of soil spiked with a heavy metals solution and to evaluate their capability in the phytodegradation of soil spiked with crude oil. The real application of these plants was then tested using landfill soil. A solution containing seventeen (17) heavy metals obtained from Perkin Elmer Pure Atomic Spectroscopy Standard (ISO 9001) was spiked to the soil samples. Ten heavy metals arsenic (As), cobalt (Co), copper (Cu), chromium (Cr), cadmium (Cd), manganese (Mn), nickel (Ni), iron (Fe), lead (Pb) and zinc (Zn) were selected for this study due to their availability hollow cathode lamps and easy detection. All samples from the plants and soils were analyzed using Atomic Absorption Spectrophotometer (AAS). The concentration of five (5) toxic heavy metals accumulated in the root of A. wilkesiana ranged between 1.71-4.08, 4.93-16.31, 16.44-27.24, 4.11-9.36 and 4.74-11.25 mg/kg for Cd, Cr, Cu, Pb and As, respectively. While the concentration of these toxic heavy metals in the root of P. fruticosa ranged between 1.85-4.67, 9.09-17.33, 16.71- 25.01, 8.22-16.42 mg/kg for Cd, Cr, Cu, Pb and As, respectively. P. fruticosa accumulated higher concentration of these toxic heavy metals on all the harvesting periods compared to A. wilkesiana. Similar trends were also observed for other five heavy metals (Co, Mn, Ni, Fe and Zn). These results suggested that these two plants could be used in heavy metals phytoremediation of contaminated soil. The overall accumulation of heavy metals by both plants on last harvesting period follow the trend Fe> Zn> Mn> Cu> Pb> Cr> Co> Ni> As> Cd, and Fe> Cu> Mn> Zn> Cr> Ni> Co> As> Cd, for P. fruticosa and A. wilkesiana, respectively. The capability of P. fruticosa and A. wilkesiana to phytoremediate the soil spiked with crude oil from Miri Sarawak was also investigated. Plants were removed from the soil on the harvesting period of 2 to 10 months and analysed for aliphatic hydrocarbons (AHs) and polycyclic aromatic hydrocarbons (PAHs) using Gas Chromatography-Flame Ionization Detector (GC-FID) and Gas Chromatography-Mass Spectrometer (GC-MS), respectively. Both plants absorbed and translocated AHs and PAHs within the harvesting period. The absorption of n-alkanes carbon (C14) to carbon (C33) by P. fruticosa and A. wilkesiana was increased with the increase of the harvesting periods. The concentration of AHs and PAHs in the roots and leaf of both plants indicated that these plants can be used for phytodegradation of soil spiked with petroleum hydrocarbons. The potential of P. fruticosa and A. wilkesiana as an accumulator has been investigated by growing these plants on an abandoned landfill soil from Matang, Kuching. Both plants were found to uptake a considerable quantity of heavy metals (As, Pb, Cr, and Cd) and hydrocarbons. The overall findings from this project suggest that phytoremediation could be applied to remediate soil contaminated with heavy metals and petroleum hydrocarbons using P. fruticosa and A. wilkesiana as accumulators