Analysis of Pollution Levels of Heavy Elements Using Fractionation Pattern of Street Soils of Langtang North, Plateau State, Nigeria

Abstract

Soil Pollution is a serious environmental challenge around the world today. Anthropogenic activities and population explosion have continued to pose great danger to our environment most especially land resources which are fixed. It is against this backdrop that this study assessed the levels of some selected heavy elements (As, Cd, Co, Cr, Cu, Fe, Mn, Ni and Zn). To achieve this, various fractions of exchangeable bound metals, carbonate bound metals, manganese oxide bound metals, iron/manganese bound metals, organic/sulphide bound metals and residual bound metals in soils of Bala, Gantang, She–for, Walang and Yangang Streets as well as Intorok Street which serves as control, Langtang North, Plateau State, Nigeria were assayed using Atomic Absorption Spectrophotometry. The results show that the bioavailable/soluble fractions ranges in (mg/kg) are for: As (BDL – 34.00), Cd (3.00 - 45.00), Co (BDL – 70.00), Cr (42.00 – 155.00), Cu (47.00 – 73.00), Fe (48.00 – 116.00), Mn (46.00 – 119.00), Ni (42.00 – 108.00), Pb (30.00 – 292.00) and Zn (45.00 – 207.00) in all the Streets investigated. The residual/ insoluble fraction ranges in (mg/kg) are for: As (BDL – 5.00), Cd (1.00 – 11.00), Co (BDL – 25.00), Cr (9.00 – 56.00), Cu (11.00 – 19.00), Fe (11.00 – 28.00), Mn (10.00 – 25.00), Ni (10.00 – 21.00), Pb (11.00 – 68.00) and Zn (9.00 – 47.00). The residual fraction is associated with minimal toxicity since migration and transformation of this fraction under general conditions are limited because of being tightly bound to Fe and Mn oxides and hydroxides. The bioavailable fraction is generally observed to be predominant in all the soil, it is usually associated with anthropogenic factors. Higher heavy element concentrations in these streets were recorded in points where there are evidences of organic load discharge and domestic effluents as in the case of Gantang, Yangang, and Bala streets. The fractionation pattern for the six streets assayed showed the northern (hill) part of Langtang North has no potential risk of contamination. However, the plain or southern part of the study area showed high potential risk that if not monitored will result in serious contamination. Topography plays an important role in the risk factor of heavy element contamination in the study area. The overall results showed evidence of some heavy metal pollution in all the Street soils assayed with possible cumulative effect over time.