ABSTRACT

 A study of the contamination of soil and groundwater at three refuse dumpsites was carried out in Aba, Abia State, Nigeria from September, 2012 to March 2013. In the process, the state of disposal/ management of solid waste and domestic water source, composition of wastes at the dumpsites and the physico 一 chemical (especially heavy metal) characteristics of soil and groundwater of the sites were investigated. Wet and dry season samples of dumpsite soils at three depths (0 一 15cm, 15 - 30cm and 30 一 45cm) and water samples from bore holes around the dumpsites were analysed for pH, electrical conductivity, phosphate, sulphate, nitrate and heavy metals such as lead, iron, cadmium, nickel, chromium and zinc. Control soil and water samples were also taken at about 10km away from the dumpsites. The pH and electrical conductivity of samples were determined using the Hannah pH and conductivity meters respectively.The phosphate, sulphate and nitrate concentrations were determined using the UV spectrophotometer while the heavy metal concentrations were determined using the atomic absorption spectrophotometer at various wavelengths. All of the above mentioned parameters analysed showed higher levels in the vicinity of the dumpsites than in the control site. Soil analyses showed downward movement ofthe contaminants as some ofthe parameters were found in significant amounts lower down the soil. The pH values of all the boreholes tested in the dry season were very low (3.66 - 4.76) compared with the WHO standard (6.5 一 8.5). Concentrations of nitrate, lead and cadmium in water samples were as high as 32.4mg/l, 0.08mg/l and 0.005mg/l respectively as against the WHO standards of lOmg/1, 0.01mg/l and 0.003mg/l respectively. Age of dumpsite, nature of activities and seasons appeared to be important factors in the occurrence and magnitude of pollution. Some of the recommendations made include building of roads to enable waste management agency access all residential areas, public enlightenment on water treatment and the use of incentives to encourage waste sorting at source. The use of extended producer responsibility and deposit refund system in waste management, waste to wealth creation, monitoring and enforcement to ensure that dumping stops at non - recommended sites and building of sanitary landfills away from residential areas are also recommended.