SEASONAL VARIATION IN TRACE METAL CONCENTRATIONS IN SOIL AND VEGETABLE SAMPLES FROM SELECTED MINING AREAS IN JOS SOUTH AND BARKIN LADI LGA, PLATEAU STATE

Abstract

In this study, the seasonal variation in concentrations of the trace metals Cu, Zn, Pb, Cd, As Ni and Co in soil and vegetable samples from farms in some mining areas in Jos South and Barkin Ladi LGA, Plateau State were investigated in two major seasons (dry and wet). This was done to assess the pollution status of the farms and hence, the safety levels of the vegetable samples. The samples were treated and digested using 10 cm3 HNO3 and 30 cm3 HCl in the ratio of 1:3. Trace metal concentrations were determined using the PG-990 model atomic absorption spectrophotometer. Analytical results of soil samples from mining areas indicated higher concentration of Cu and As for both seasons than the values reported by the FAO/WHO (2007). Similarly, the metals Cu (15.12±1.50 mg/kg), Zn (76.45±2.40 mg/kg), Pb (23.75±1.35 mg/kg), Cd (3.69±0.15 mg/kg), Ni (17.80 ±0.15 mg/kg) and Co (28.14+1.35 mg/kg) showed high concentrations in dry season than wet season. Comparing the vegetable samples, spinach was found to accumulate high concentration of trace metals than tomato and Irish potato. In general, the levels of trace metals in soil and vegetable samples were higher in dry season than in wet season. The levels of Pb, Cd, As, Ni and Co were significantly above the critical toxic level in vegetables as reported by WHO/FAO (2007), while Zn and Cu occurred within the acceptable limit for both seasons.