ENVIRONMENTAL IMPACT OF SILICA SAND EXCAVATION IN BADAGRY AREA, LAGOS STATE, NIGERIA

Abstract

The study investigates environmental impact of silica sand excavation in Badagry area, Lagos Nigeria as it affects the excavation activities in the area of interest. The chemical properties of silica sand sample in the selected locations were carried out in accordance with Federal Environmental Protection Agency (FEPA) standards. The average results of atomic absorption spectrophotometer (AAS) analysis for the four locations shows the presence of some major oxides in it mineralogical composition which includes SiO2, TiO2, Al2O3, Fe2O3, MgO, CaO, Na2O, and K2O. The average silica (SiO2) content for the locations is 80.96 % high. The other oxides with appreciable high value are Titanuim oxide (TiO2), Ferric oxide (Fe2O3), and alumina (Al2O3) with average values of 1.64 %, 1.6 %, and 1.34 % respectively. All other oxides such as alkalis (Na2O, and K2O), and alkaline earth (MgO, and CaO) have average values of 0.15 %. The average pH value of silica sand for the locations was 7.77 which are less than 8 and not corrosive while organic carbon, nitrogen and phosphorus was having appreciable values. The average organic matter content of soil was 0.71 % which increases with distances away from silica sand sites. The grain size distribution for the locations was classified into SC – SM (silt clayey sand) based on unified classification of soil sample. The results obtained indicated that soils around the silica sites were not degraded chemically this is because the average values of heavy metal was 0.01 mg/L was below level of possible water/soil contamination and soil acidity. The acidity and concentrations of heavy metals viz zinc, lead and iron at the various locations were low as a result of distance away from the silica sand sites. Acidity and concentrations of cations such as magnesium, calcium ions and anions such as sulphates, nitrates of water at silica sand sites were moderate at various locations. The results obtained from water analysis were compared with World Health Organisation (WHO) drinking water standard. It could be deduced that after thorough examination of the soil and water samples in and around the silica sand site there is marginable negative effects of exploitation of the deposit on the surrounding communities.