ASSESSMENT OF SOME HEAVY METALS ACCUMULATION IN BORRERIA VERTICILLATA (L.) FOUND ALONG ZARIA-GIWA ROAD, KADUNA STATE, NIGERIA
The levels of some heavy metals (lead, cadmium, copper and zinc) were assessed in roadside soils and different organs of Borreria verticillata (L.) plants along Zaria-Giwa road, Kaduna state, Nigeria. The soils and plants samples were collected at distances of 0, 5, 10, 20, 40 and 100 m from the roadside at four different locations namely: Ahmadu Bello University Teaching Hospital (ABUTH), National Animal Production Research Institute (NAPRI Shika), Marabar Guga and Ahmadu Bello University Dam Quarters. The samples were digested following the standard procedure. Atomic absorption spectrophotometer (A.A.S.) was used in the determination of the metal ions concentration in the samples. The data obtained were subjected to Analysis of Variance (ANOVA) and Duncan’s Multiple Range Test (DMRT) where necessary. The result showed that, the heavy metals in the soil and plant samples had higher concentration at 0 m and decreased progressively with increase in distance from the roadside. The range of the elements levels in B. verticillata were Pb (4.82-22.34 mg/kg), Cd (1.02-4.29 mg/kg), Cu (5.03-62.18 mg/kg) and Zn (10.22-95.05 mg/kg). Pb and Cd were above the permissible limit set by FAO/WHO. All the highest metal concentrations were observed in the roots of the plant at ABUTH except for Pb. Heavy metal concentrations in soil and plant samples from ABU Dam quarters (control) were significantly lower than those of other locations. In conclusions, distance from the roadside and vehicular densities had a significant effect on the heavy metal concentrations in the samples.