Impact of Heavy Metals on the Soil and Groundwater of Ariaria Waste Dumpsite, Aba, South-Eastern Nigeria

Abstract

Municipal waste around Ariaria, Aba, Nigeria, was investigated to ascertain the impact of heavy metals on the soil and groundwater. Eighteen (18) soil samples were collected with each of the sampling point having three (3) soil samples collected at the depth of 0-10 cm, 10-20 cm and 20-30 cm and ten (10) groundwater samples were also collected from an existing borehole. Control soil samples were collected opposite the dumpsite area. The physio-chemical and heavy metal parameters of the soil and groundwater samples were assessed using Atomic Absorption Spectrophotometry (AAS) and Titrimetric method, respectively. Heavy metals analyzed for includes zinc, lead, iron, chromium, cadmium, copper, nickel, manganese, and cobalt. The average mean concentration of the heavy metals includes lead (6.252 mg/kg), chromium (7.486 mg/kg), iron (1493.598mg/kg), manganese (89.84 mg/kg), cobalt (16.2 mg/kg), cadmium (2.754 mg/kg), copper (41.53 mg/kg), zinc (270.4 mg/kg) and nickel (15.858 mg/kg). The mean concentration of heavy metals of the soil samples are in this order: Fe>Zn>Mn>Cu>Co>Ni>Cd>Pb>Cr. The physio-chemical parameters (pH, electrical conductivity, Total hardness, total dissolved solids, total suspended solids, major anions and cations) analyzed for all groundwater samples agree with the International World Health Organization (WHO) for potable water except pH and TDS (mg/l. The heavy metal contents include manganese (0.168 mg/l), cadmium (0.28 mg/l), lead (0.046 mg/l), nickel (0.12 mg/l), cobalt (0.016 mg/l), chromium (0.087 mg/l), copper (0.5 mg/l), magnesium (1.84 mg/l), zinc (0.023 mg/l) and iron (1.42 mg/l). The sieve analysis shows that the soil samples consist of 11.95% of Silt, 83.62% of Sand and 4.42% of little gravel. The mean permeability of the study area ranges from 0.19 (cm/sec) to 0.49 (cm/sec), the mean infiltration rate ranges from 6840 mm/hr to 31320 mm/hr and the grain size of the soil samples is well graded and well to poorly sorted. A strong degree of association was found to exist between lead and chromium, copper and zinc, nickel and lead using Pearson’s Correlation Coefficient.