FUW TRENDS IN SCIENCE & TECHNOLOGY JOURNAL
(A Peer Review Journal)
e–ISSN: 2408–5162; p–ISSN: 2048–5170
keywords: Gongronema latifolium, Talinum triangulare, Amaranthus hybridus, Geo-accumulation index
Heavy metals contamination of soil has continued to increase globally as a result of increase in anthropogenic actions. The phytochemical and heavy metals (Zn, Cu, As, Pb, Cd, Hg) content of three edible plant species grown in southern Nigeria and their health implications were evaluated. Heavy metal concentrations in Gongronema latifolium, Talinum triangulare and Amaranthus hybridus as well as the top soil were determined using Atomic Absorption Spectrophotometer. Geo-accumulation index and Transfer factors were used to evaluate the extent of contamination of top soil and exposure by human via the food chain respectively. The results of phytochemical analysis of plants revealed the existence of some bioactive constituents which varied with their corresponding concentrations as presented in increasing order of magnitude: anthocyanin˂ carotenoid ˂ flavonoid ˂ tannin ˂ steroid ˂ alkaloid. Soil analysis for heavy metals show that zinc had the maximum concentration (103.1 – 174.0 mg kg-1) while mercury had the lowest levels (0.01 – 0.20 mg kg-1). Heavy metal concentrations in the soil samples were in the order; Zn ˃ Pb ˃ Cu ˃ Cd ˃ Ni ˃ As ˃ Hg. Geo-accumulation index analysis revealed that Pb and Cd were implicated in overall contamination of the soil samples but the control soil remained uncontaminated. The concentrations of heavy metal in the plant samples varied greatly with Zn having the maximum values (10.80 – 21.10 mg kg -1) whereas arsenic had the minimum concentration (0.01 – 0.03 mg kg-1). Heavy metal concentration in the plant samples were in the order; Zn ˃ Cu ˃ Pb ˃ Cd ˃ Ni ˃ Hg ˃ As. The concentrations of heavy metals in the selected plant samples evaluated were within the recommended standard limits apart for lead which was higher than the recommended value. Results revealed moderately high transfer factors, and the capacity of the vegetables investigated to accumulate copper, mercury and arsenic.
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