IMPACT OF INDUSTRIAL WASTES ON SURFACE AND GROUNDWATER QUALITY USING GEOPHYSICAL & PHYSICOCHEMICAL METHODS IN MOSIMI & ITS ENVIRONS

Abstract

ABSTRACT Different forms of wastes are produced by industries many of which are released consciously or unconsciously into the water bodies in the environment. The aim of this research work is to quantify the impact of industrial wastes on both surface and groundwater quality using geophysical and physicochemical techniques. The research was carried out at Likosi/Mosimi along Sagamu – Ikorodu industrial axis. The region host cement factory, metal smelting and extraction Companies, petroleum depot of NNPC, agro allied industries etc. Electrical resistivity tomography (ERT) was used for geophysical investigation, hence eight (8) 2D lines (Constant Separation Transversal) each with six (6) movements and sixteen (16) VES points (Vertical Electrical Sounding) which span an approximate distance of 1.5 Km was used for the electrical resistivity investigation. Also five samples of surface water were collected from three rivers and two streams as well as five samples of groundwater were collected from three hand dug wells and two bore holes around the study area for physicochemical analysis. Two approaches used to estimate vulnerability of the groundwater are longitudinal conductance (S) method and AVI model (Aquifer Vulnerability Index) which uses two parameters namely thickness of overburden and hydraulic resistance (c) to estimate aquifer protective capacity. Longitudinal Conductance (S) method uses six ratings namely Excellent (S > 10), Very Good (S between 5 and 10), Good (S between 0.7 and 4.9), Moderate (S between 0.2 and 0.69), Weak (S between 0.1 and 0.19) and Poor (S < 0.1). AVI model uses five (5) vulnerability ratings namely extremely high (log c < 1), high (log c lie between 1 and 2), moderate (log c lie between 2 and 3), low (log c lie between 3 and 4) and extremely low (log c > 4) as a measure of an aquifer vulnerability. The result of longitudinal conductance method reveals that 75% of aquifer in the study area is poorly protected, 18.75% is moderately protected and 6.25% weakly protected but the AVI model shows that 68.75% of the aquifers in the area has moderate vulnerability while 31.25% has low vulnerability by virtue of geological formations. Physicochemical analysis revealed that 40% of surface water is acidic, 40% basic and 20% neutral while 80% of groundwater is acidic and 20% neutral. For both surface and groundwater, Sulphate, nitrate and chloride content are within safe zone of World Health Organization (WHO) recommendation. Also all tested metallic ions which include Calcium, Magnesium, sodium, Manganese, lead, zinc and cooper are below maximum consumption limit of WHO except iron, which has measured range of 0 – 0.9 mg/liter for surface water and 0 – 1.1mg/liter for groundwater against WHO maximum limit of 0.3 mg/l. Sulphate and phosphate contents of all the samples ranges from 0 – 39.9 and 0 – 0.92 mg/l respectively which are within WHO limit of 150 and 250mg/l respectively. Nitrate and nitrite content of the samples ranges from 19.2 – 554.2 mg/l and 6.7 – 96.3 mg/l respectively which far exceed 10mg/l and 1 mg/l limits of WHO. Therefore, it is concluded that the effect of industrial waste on surface and groundwater quality around the study area is mild nevertheless industrial wastes should be processed prior to disposal to the environment considering iron, nitrite and nitrate content of the water bodies in the area.