Environmental impact of landfill on groundwater quality and agricultural soils in Nigeria

Physical, chemical and bacteriological analyses were carried out of water samples from three boreholes located near a landfill, and or soil samples at Akure, Nigeria, to ascertain the effect of the dumpsite on the groundwater and soil quality. The samples from borehole locations with radial distances of 50, 80, and 100 m, respectively, away from the landfill and twelve soil samples collected at distances 0 (dump centre), 10, 20, and 30 m away from the refuse dump were analysed. The parameters determined were the turbidity, temperature, pH, dissolved oxygen (DO), total dissolved solids (TDS), total hardness (TH), total iron, nitrate, nitrite, chloride, calcium and heavy metals like copper, zinc, and lead. Most of these parameters indicated pollution but were below the World Health Organization (WHO) limits for consumption. The pH ranged from 5.7 to 6.8 indicating toxic pollution, the turbidity values were between 1.6 and 6.6 NTU, and the temperature ranged from 26.5°C to 27.5°C. The concentrations of iron, nitrate, nitrite and calcium ranged from 0.9 to 1.4, 30 to 61, 0.7 to 0.9, and 17 to 122 mg/l, respectively. Out of heavy metals, zinc ranged between 3.3 and 5.4 mg/l and lead ranged from 1.1 to 1.2 mg/l. Soil water holding capacity, porosity, pH, organic matter, organic carbon and organic nitrogen ranged from 38 to 54, 44 to 48, 6.9-7.5, 2.44-4.27, 1.42-2.48, and 0.12-0.21%, respectively. Statistical analyses indicated significant differences at 95% level. The results showed that all the boreholes were not strongly polluted but require treatment before use while the soil is absolutely unsuitable for the crop production. Re-designing of sanitary landfills to prevent leachate from getting to the water table, adoption of clean technology for recycling greenhouse gases and a sustainable land management programme for reclamation are recommended.