A Determination of Phytoremediation by Native Species in Bauxite Spoil Dump: A Case Study of Kara-Kara, Linden, Guyana

The difficulty in selecting species that can grow in degraded bauxite areas is a result of limited information on the Silviculture and ecological requirements of tropical native/exotic species. The main aim of this project was to assess the phytoremediation properties of the native species in areas degraded by bauxite mining. This study was conducted on an experimental site located in Kara Kara bauxite mined dump in Linden, Guyana. Soil and plant samples were collected from the study area. The study site was colonized by four native species Chrysobalanus icaco (Fat pork), Tapirira guianensis (Duka), Maprounea guianensis (Awati), and Anacardium occidentale (Cashew). One-way ANOVA from Statistix 10 Software Package was utilized to compare the heavy metal concentrations at two soil depths (0–15 cm and 15–30 cm). Very low levels of heavy metals presence were observed from the results of soil analysis in the study area. Lead (Pb) recorded the highest heavy metals concentration (13ppm) in the soil. Cadmium (Cd) had the lowest (0.3ppm) when compared to Arsenic (As) and Mercury (Hg) which had 3ppm and 1ppm respectively. The presence of heavy metals (Arsenic and Mercury) was found in plant tissues of the four species that colonized the study area. Awati and Cashew had the highest heavy metal concentration of Arsenic with 4ppm for Awati and 3ppm Cashew. The concentration of the other three heavy metals was too negligible to report on. In conclusion, the four native species Chrysobalanus icaco (Fat pork), Tapirira guianensis (Duka), Maprounea guianensis (Awati), and Anacardium occidentale (Cashew) have the ability to phytoremediate Arsenic and Mercury however not Cadmium and Lead. More trials needed to be conducted at different bauxite mined sites on the two species Awati and Cashew for phytoremediation and rehabilitation. This research should be replicated over a longer period of time at different bauxite sites with other species in order to identify those that can phytoremediate Pb and Cd.

Mycorrhizal Association Determination should be conducted on plant roots at depths greater than 30cm in the soil profile and on finer roots to identify the mycorrhizae in the species on the bauxite mined-out site.