Bioaccumulation Factors and Pollution Indices of Heavy Metals in Selected Fruits and Vegetables From a Derelict Mine and Their Associated Health Implications

Abstract

Concentration of heavy metals in the top and sub soils and in selected vegetables and fruits grown in Enyigba lead-zinc mine derelict was investigated using the X-ray Fluorescence (XRF) spectrometric method. Samples of fruits and leaves of the studied plants, over a period of two years (2008-2010), were analyzed for arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), manganese (Mn), lead (Pb), and zinc (Zn) contents, and their corresponding Pollution Indices (PI) and Bioaccumulation Factors (BAF) were evaluated. The mean pH of the soil was found to be 6.5 and the mean concentrations (mg/Kg) of metals in the studied plants were of the range: Pb (0.22 – 6.72); As (0.10 – 10.6); Cd (0.10 – 12.4); Cu (12.6 – 82.1); Cr (0.01 – 1.02); Zn (34.2 – 162.1); Mn (412.1 – 42.6); and Ni (12.8 – 72.8). High Pollution Indices of 22.4, 12.37, 8.67, 7.27, and 6.13 were observed in Nauclea latifolia (African Peach), Sesamum indicum (Beni seed), Lactuca Sativa (Lettuce), Psidium Guajava (Guava), and C. Annum (Pepper) respectively; and as a result, they were not considered fit for human consumption. Bioaccumulation Factors (BAF > 1) were observed in some of the studied plants which suggested that they could be good phytoremediation agents. Statistical analysis of variance (ANOVA) at p< 0.05 showed variations in the heavy metal levels between and within groups while Fisher’s Least Significant Difference (LSD) Correlation analysis identified a strong relationship between the investigated plant and soil samples.