EVALUATION OF ENVIRONMENTAL POLLUTION ARISING FROM TWO MAIN WASTE DUMPSITES IN ONDO TOWN, ONDO STATE, NIGERIA

Abstract

Soil and water contaminated with toxic metals and micro-organisms can result to serious environmental hazards. As a result of these problems, this research was carried out to investigate the physicochemical properties, concentration of heavy metals, and microbial load (bacteria and fungi) in Epe and Laje dumpsites in Ondo town, Ondo State. A total number of eighteen samples consist of both top and subsoil of the dumpsites and the well water 400-800m away from the dumpsites were collected between April to June 2017 and taken to the laboratory for analysis in order to ascertain the concentration, mobility of toxic metals and evaluation of possible impacts of the dumpsites on the groundwater. Physicochemical properties were determined under standard procedures, heavy metals were sequentially quantified using atomic absorption spectrophotometry (AAS), and pour plate technique was used to determine the microbial load, isolation and identification of the soil and water samples. National Environmental Standard and Regulation Enforcement Agency acceptable limit and index was used as standard measure for the purpose of comparison. The physico-chemical properties of water ranged as follows: pH (9.90-10.90), Conductivity (62.00-74.00μ/cm) and Total suspended solid (54.64-62.41) values exceeded the standard measure while other physico-chemical properties such as Nitrate, Sulphate, Chloride, Total dissolved solid, Total solid, Dissolved Oxygen, Biological Oxygen Demand and Chemical Oxygen Demand values were below the standard measure. Furthermore, the concentration of heavy metals in water ranged as follows: Zinc (3.32 - 3.47), Cadmium (0.17 - 0.21), Iron (46.19 - 54.20), Copper (4.86 - 5.93), Nickel (1.21 - 1.41) and Chromium (0.96 - 1.00) all in (mg/L) exceeded the standard measure except Lead. For soil, the physico-chemical properties of the soil (top and sub) ranged as follows: pH (5.89-8.44), % Sand (52.65-69.33), % Silt (8.18-12.58), % Clay (18.63-37.10), % Total Organic Matter (29.27-37.59), and Electrical conductivity (1000-1079μ/cm). However, the pH, Conductivity and % Clay increase along with depth of the soil. The results of heavy metals analysis showed that Iron and chromium with concentration of (109.38-172.36) and (0.31-0.79) respectively exceeded standard measure while the concentration of other heavy metals ranged as follows, Zinc (4.01 – 6.76), Cadmium (0.05- 0.32), Lead (0.21 - 0.56), Copper (0.61 - 0.82) and Nickel (0.17 - 0.21) all in mg/kg were below the standard measure for the soil samples and the order was Fe>Zn>Cu>Cr>Pb>Cd>Ni for Epe and Laje dumpsites. Nine (9) different bacteria and Four (4) different fungi were isolated, characterized and identified from Epe and Laje dumpsites. The bacteria identified included Staphylococcus aureus, Steptococcus faecalis, Escherichia coli, Klebsiella pneumonia, Bacillus subtilis, Proteus mirabilis, Micrococcus luteus, Clostrodium Spp and Pseudomonas Spp and while the Fungi identified included Mucor mucedo, Aspergillus spp, Penicillum notatum and Candida albican. Of all organisms isolated, E.coli and A.flavus had the highest percentage for bacteria and fungi respectively. Waste management in Ondo State should look for measures to curb indiscriminate dumping of refuse and look for probable recycling of the wastes.