ABSTRACT

This work examined the levels of heavy metals in soils of Port Harcourt metropolis and their relationship with the physicochemical properties of the soil. It also compared the concentrations of these elements in the soils of residential and industrial sites. Samples in triplicate (0-10, 10-20,20-30) were collected as follows; twelve samples from four sites, six from two industrial sites, Trans Amadi and Oil mill market and therefore six from two residential sites Borokiri and GRA Diobe . Cathnium, chromium, iron, nickel, copper, zinc, arsenic and lead were analyzed by the use of 969 Unlearn Atomic Absorption Spectrophotometer and expressed in ug/g. Levels of Cd in the Port Harcourt soils ranged from 3.16±0.21 to 4.80±0.44 with a mean value of 3.88±0.19, Cr ranged from 0.31±0.07 to 1.27±0.35 with a mean value of 0.70±0.09, Fe ranged from 19.22± 1.26 to 24.84±1.26 with a mean value of 20.63 ±0.03 ,Cu ranged from 6.80±0.52 to 10.67±0.67 with a mean value of 8.80±0.41, Zn ranged from 3.10±0.56 to 8.03±0.10 with a mean value of 5.5 1±0.43, As ranged from 0.09±0.01 to 0.14±0.02 with a mean value of 0.12±0.01 and Pb ranged from 2.69±0.16 to 5.85±0.55 with a mean value of 4.36±0.33. The levels of As, Cu, Fe, Ni and Zn were lower than permissible levels for Canadian environmental quality criteria and lower still when compared with values reported by other workers in the literature. Physicochemical properties determined included pH, electrical conductivity, total nitrogen, available phosphorus, particle size distribution, organic carbon, total hydrocarbon, exchangeable bases, exchangeable acidity, nitrate, sulphate, cation exchange capacity and base saturation. Physicochernical properties compared well with those reported by other workers for soils of basement complex of Western Nigeria. Levels of these heavy metals were correlated with the soil parameters and also the soil parameters correlated among themselves using Michigan State University Software Program for the design, management and analysis of agronomic research experiment (MSTATC) statistical package. Results show that Port Harcourt soil of residential and industrial areas are not polluted in terms of multi element contamination even though certain heavy metals Cd, Pb and Cr levels point to the fact that they are potential pollutants. Consequently the data point to the need for proper monitoring so as to maintain or reduce the present levels. This is further confined by pollution index, which was calculated to be 0.58. Pollution index of less than I shows no multi-element contaminated soil.