Seasonal Variations of pH and Heavy Metals Content in Soil of Selected Housing Estates in Ogun State, Nigeria

Abstract

There is a necessity to assess soil properties with the view to determining soil qualities relative to pollution and sustainability of ecosystem functions and plant productivity regardless of the scale. Soil samples (six points per site at 0-15 cm depth) from six selected housing estates across Ogun State were assessed for soil pH and heavy metals pollution in two dry and rainy seasons. The soil samples were digested using standard methods and analysed for seven selected metals: Mn, Fe, Cu, Zn, Ni, Pb and Cd using AAS. The data obtained were subjected to descriptive and inferential statistics. Concentrations (mg/ kg) of the analysed metals were observed to vary from the lowest in the 2nd rainy season to the highest in 1st dry season respectively as Pb: 3.57 ± 0.02 to 39.87±0.47, Cd: 0.32±0.03 to 2.65±1.02, Mg: 11.94 ± 0.76 to 204.50 ± 15.02, Fe: 22.79 ± 0.45 to 303.50±16.52, Cu: 0.95±0.21 to 6.02±1.12, Zn: 0.12 ± 0.04 to 12.75±0.68, and Ni: 2.38 ± 0.33 to 33.89±0.37. There were indications that the soil samples were comparatively less polluted in the rainy seasons.

Key words: soil qualities, ecosystem function, dry and rainy seasons, Nigeria