Abstract:
These findings documented the physical, chemical and heavy metal contents in leachate, borehole water, surface stream, treated water and soil samples around the municipal solid waste dumpsite at Uyo metropolis, Akwa-Ibom State, Nigeria. Samples were collected during the wet and dry seasons 2010/2011. The samples were analysed for the following parameters: heavy metals (Fe, Cu, Mn, Zn, Cr, Cd, Pb), anions (PO34,SO2-4,Cl-, NO-3, NH+4-N), essential metals (Na, K, Ca, Mg), total dissolved solids (TDS), dissolve oxygen (DO), Chemical oxygen demand (COD), pH, salinity, turbidity and conductivity. The results revealed that most of the parameters recorded for the leachate samples significantly exceeded the WHO international standards for drinking water in both seasons. Fe (47.33 and 113.13mg(L), Cd (2.29 and 14.47mg/l), Cu (5.78 and 35.87mg/l), Cr (1.63 and 7.63mg/l), Pb (12.33 and 31.13mg/l), Zn (17.33, and 34.5mg/l), BOD (52.2 and 159.6mg/l), Cl- (284.37 and 536mg/l), NO-3 (74.03 and 87.83mg/l), TDS (1709.5 and 2043mg/l) and DO (1.73 and 2.73mg/l). In leachate, all the heavy metals, Cl-, COD, salinity, and conductivity contents showed significant increase (P<0.05) while SO2-4 recorded significant decrease (P<0.05) during the dry season. The physico-chemical contents recorded for the borehole water and treated water samples in both seasons agree with the international standards for drinking water, except for high PO43- content (1.13 to 2.17mg/l) recorded for the borehole water samples in both seasons which exceeded the WHO permissible limit of 0.1mg/l for drinking water. The borehole water sample recorded significant increase (P<0.05) in Fe, Mn, Na, K. and a significant decrease in SO2-4 contents during the dry season. The stream water sample recorded high Fe (0.61 and 2.5mg/l) content in both seasons and high Mn (2.37 mg/l), Cr (0.42mg/l), Cd (0.46mg/l) and Cu (3.95mg/l) contents during the dry season which exceeded the WHO international standard for drinking water. The stream water samples recorded significant increase in BOD5, Cu, Mn, Cd and Cr contents during the dry season (P<0.05). The heavy metal contents recorded for soil samples from the dumpsite, from 10 and 20m east, west, south and north of the dumpsite and from the control site were all within the WHO international standards in both seasons. The heavy metal contents in the dumpsite soil sample in both seasons were significantly higher; pb (9.90 and 11.82mg/kg), Zn (1370 and 146mg/kg), Ni (12.56 and 11.82mg/kg), Cr (3.60 and 4.05mg/kg) Cd (9.05 and 12.2mg/kg) and Mn (94.0 and 91.2mg/kg) In both seasons than the control; Pb (3.78mg/kg) Zn (50.90mg/kg), Ni (2.19mg/kg), Cr (1.06mg/kg), Mn (44.27mg/kg), and Cd (1.09mg/kg). Heavy metal contents for soil samples 10 and 20m east of the dumpsite were also significantly higher (P<0.05) than that of the control. This study infer that the solid waste dumpsite is affecting the natural quality of the ambient environment. Therefore indiscriminate dumping of solid waste at the dumpsite should be prohibited.
