STUDY ON PHYSICOCHEMICAL AND LEVELS OF SELECTED METALS IN THE SOILS OF ABUJA METROPOLIS, NIGERIA

Abstract

A study of Abuja soils was carried out to determine physicochemical parameters and levels of selected metals. Flame atomic absorption spectrometer was used to determine total metal concentration. Aqua-regia (HCl-HNO₃-H₂O in the ratio 1:1:1) for the determination of the concentrations of Zn, Mn, Cu and As in the soils was employed also. Range of urban soil parameters were: electrical conductivity(16.20±0.20-374±0.50), pH(6.30±0.30-7.20±0.20), SO₄(7.40±0.40-127.35±0.07)and Cl (25.02±0.02-65.05±0.01). Range of parameters in sub urban soil samples were: EC(12.10±0.10–269.05±0.05), pH(2.20±0.20-7.20±0.20),SO₄(11.25±0.0766.35±0.07)and Cl(40.02±0.02–60.02±0.03).Sequence of metals concentrations in urban soils is as follows: Zn>Cu>Mn>As, sub urban soil samples had :Zn>Cu>Mn>As. Excess SO₄ in Abuja soils can devastate the environment with acid rain.  Excess Cl in Asokoro Forest portends danger to the environment as it destroys plants and aquatic habitat. Excess Zn in the soils inhibits photosynthesis in plants, thereby increasing the amount of CO₂ in the atmosphere, causing global warming and also excess Cu in Abuja soils can interfere in the decomposition and other microbial activities in the soils, thereby affecting soil balance.  An effective measure such as environmental risk assessment should be conducted periodically by relevant authorities towards controlling Zn contents in Abuja soils in order to reduce global warming.