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.
Aleksandra NS, Alina K, Marta KC, Janina G & Agnieszka ZR 2013. Accumulation of heavy metals and antioxidant responses in Vicia faba plants grown on monometallic contaminated soil. Environ Sci. Pollut. Res., 20: 1124–1134. AL-Rmali SW 2012. Dietary intake of cadmium from Bangladeshi foods: Cadmium exposure from Bangladeshi food. J. Food Sci., 77(1): 26-33. Aktaruzzaman M, Fakhruddin ANM, Chowdhury MAZ, Fardous Z & Alam MK 2013. Accumulation of heavy metals in soil and their leavy vegetables in the region of Dhaka Aricha Highway, Savar. Bangladesh, Pak. J. Bio. Sci., 16 (7): 332-338. Aruleba JO & Ajayi AS 2012.Heavy metal pollution status of soils in some locations at Ado Ekiti, Southwestern Nigeria. Int. J. Agric. Sci., 2: 256-264. Azeez L, Adeoye MD, Majolagbe TA, Lawal AT & Badiru R 2012. Antioxidant activity and phytochemical contents of some selected Nigerian fruits and vegetables. Am. J. Chem., 2(4): 209-213. Chang ST, Wu JH, Wang SY, Kang PL, Yang NS & Shyur LF 2001. Antioxidant activity of extracts from Acacia confusa bark and heartwood. J. Agric. Food Chem., 49: 3420–3424. Christopher IA & Therese NN 2010. Heavy metal contamination of surface soil in relationship to land use patterns: A case study of Benue State, Nigeria. Materials Sciences and Applications. 1: 127-134. Chojnacka K, Chojnacki A & Górecka H 2005. Biosorption of Cr3+, Cd 2+ and Cu 2+ ions by blue- green algae Spirulina sp. kinetics, equilibrium and the mechanism of the process. Chemosphere, 59: 75–84. Chukwuemeka AN, Godwin JU & Alfreda ON 2015. Investigations of heavy metals concentrations in leaves of Telfairia occidentalis Hook; F. (Fluted Pumpkin) in Nigeria. Pol. J. Environ. Stud., 24(4): 1733-1742. Cui YL, Zhi RH, Chen DY, Huang YZ & Qui Y 2004. Transfer of metals from soils to vegetables in an area near a smelter in Nanning, China. Environ. Intl. 30: 785 -791. Duruibe JO, Ogwuegdu MD & Egwurugwu JN 2007. Heavy metal pollution and human biotoxic effects. Int. J. Physical Sci., 2: 112-118. Elias KM, Nelson KO, Simon MK & Johnson KK 2012. Phytochemical and antioxidant analysis of methanolic extracts of four african indigenous leafy vegetables annals. Food Science and Technology, 13(1): 37-42. FAO/WHO 1976. List of maximum levels recommended for contaminants by the joint FAO/WHO Codex Alimentarias Commission. 2nd Series, CAC/FAL, 3: 1-8. Goel S, Malik JA & Nayyar H 2009. Molecular approach for phyto-remediation of metal contaminated sites. Archives of Agronomy and Soil Sci., 55(4): 451-475. Guala SD, Vega F & Covelo EF 2010. Heavy metal concentration in plants and different harvestable parts; A soil-plant equilibrium model. Environ Mental Pollution, 158: 2659 –2663. Harborne JB 1973. Phytochemical Methods: A guide to modern techniques of plant analysis. London. New York; Chapman and Hall. Jolly YN, Islam A & Shawkat A 2013. Transfer of metals from soil to vegetables and possible health risk assessment. J. Springer Plus, 2: 385 Lokeshwari H & Chandrappa GT 2006. Impact of heavy metal contamination of Bellandur Lake on soil and cultivated vegetation. Curr. Sci., 91(5): 622 – 627. Muller G 1996. Index of geoaccumulation in sediments of the Rhine River. Geol J., 2: 109 –118. Nouri J, Khorasani N, Lorestani B, Karami M, Hassani AH & Yousefi N 2009. Accumulation of heavy metals in soil and uptake by plant species with phytoremediation potential. Environ Earth Sci., 59: 315–323. Ogoko EC 2015. Accumulation of heavy metal in soil and their transfer to leafy vegetables with phytoremediation potential. Am. J. Chem., 5(5): 125-131. Okeke CU & Elekwa I 2003. Phytochemical study of the extract of Gongronema latifolium Benth. J. Health and Visual Sci., 5(1): 47-55. Okwu DE 2005. Phytochemicals, vitamins and mineral content of two Nigeria medicinal plants. Int. J. Molecular and Advance Sci., 1(4): 375 – 381. Onyeka EU & Nwambekwe IO 2007. Phytochemical profile of some green leafy vegetables in South-East, Nigeria. Nigerian Food Journal. 25(1). Opaluwa OD, Aremu MO, Ogbo LO, Abiola KA, Odiba IE, Abubakar MM & Nweze NO 2012. Heavy metals concentrations in soils, plant leaves and crops grown around dump sites in Lafia Metropolis, Nasarawa State, Nigeria. Advance in Appl. Sci. Res., 3(2): 780-784. Osu CI & Ogoko EC 2014. Bioconcentration and transfer of heavy metal from soil into Verninia amydalina, Telfera occidendalis and Amaranthus spinosus. J. Appl. Phytotech. Envtal. Sanitation, 3(4): 117-121. Osundiya MO, Ayejuyo OO, Olowu RA, Bamgboye OA & Ogunlola AO 2014. Advances in Applied Science Research, 5(1): 1-7. Prabu PC 2009. Impact of heavy metal contamination of Akaki river of Ethiopia on soil and metal toxicity on cultivated vegetable crops. Electronic J. Envtal. Agric. and Food Chem. Raghavendra M, Reddy AM, Yadav PR Raju AS & Kumar LS 2013. Comparative studies on the in vitro anti-oxidant properties of methanolic leafy extracts from six edible leafy vegetables of India. Asian J. Pharm. Clin. Res., 6(3): 96-99. Ramesa SB & Sooad AD 2014. Phytochemical constituents and antibacterial activity of some green leafy vegetables. Asian Pac. J. Trop. Biomed., 4(3): 189-193. Rasaq AO, Gregory OA, Olumayowa JO, Oladipo AL & Owolabi MS 2015. Concentration of heavy metals in root, stem and leaves of Acalypha indica and Panicum maximum Jacq. from three major dump sites in Ibadan Metropolis, South West Nigeria. Am. J. Chem., 5(1): 40-48. Regulation (EC) No 629/2008: Amending Regulation (EC) No 1881/2006 setting maximum levels for certain contaminants in foodstuffs. Sajjad K, Robina F, Shagufta S, Mohammad AK & Maria S 2009. Health risk assessment of heavy metals for population via consumption of vegetables. World Applied Sci. J., 6(12): 1602 – 1606. Sepp T, Karu U, Sild E, Männiste M & Hõrak P, 2011. Effects of carotenoids, immune activation and immune suppression on the intensity of chronic coccidiosis in greenfinches. Experimental Parasitol. J. Sci. Direct, 127(3): 651-657. Singh B 2001. Heavy metals in soil: sources, chemical reactions and forms. In: D. Smith, S. Fityus and M. All man (eds.), Geotechnics: Proceedings of the 2nd Australia and New Zealand Conference on Environmental Geotechnics, Newcastle, NSW, Australia, pp. 77-93. Wright DJ & Otte ML 1999. Plant effects on the biogeochemistry of metals beyond the rhizosphere. Biol. Environ Proc R Ir Acad., 99B(1): 3–10.