Assessment of heavy metal pollution in pece channelized stream water Gulu town, northern-Uganda

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Kampala International University, Colleges of Humanities and Social sciences
Water quality monitoring in developing countries is inadequate, especially in stream water affected by urban effluents and runoff. The purpose of this study was to investigate heavy metal contaminants in the Pece Stream water in Gulu Municipality, Northern-Uganda. Water samples were collected along the channel of Pece stream and other samples from Nakaseke River which served as a control site. Selected heavy metals (Zinc, Copper, Lead and Cadmium) were determined using Atomic Absorption Spectrophotometry. Sampling of water was done during the dry and the wet seasons of the years 2011 and 2012, respectively. Physicochemical parameters were also determined for Electrical conductivity, pH, hardness of water, Total Suspended Solids (TSS) and Chemical Oxygen Demand (COD). Results indicate that heavy metal concentrations in Pece stream water were significant. The mean concentration of Zinc ranged between 0.64 } 0.0040 and 0.78 } 0.0095. Copper gave mean total concentrations between O.0880 }0.0054mg1’ and 0.0420 }0.0072mg/i during the two consecutive years of the study. All these values obtained for Zn and Cu were within the maximum permissible limits of WHO (2008), NEMA (2006) and USEPA (2005). The total lead concentrations in the samples were <0.003 mg/l, this was below the permissible limits of WHO (2008), NEMA (2006) and FMENV (1991). Cadmium was detected at a very low level in all the samples with the highest Mean concentration being 0.005 } 0.002 1 mgl’ and the lowest 0.003 } 0.0002 mgl’ which is below the water quality standards. The average pH of the filtered water samples at 25°C was between 7.04 } 0.0011 and 7.24 } 0.0008. Electric conductivities were comparatively high, with average values ranging between 226.3 } 0.0352 and 232.5 } 0.0048, more than 200-fold that of pure distilled deionised water. The levels of average hardness were between 95.8 } 0.0125 and 103.3 } 0.1106 compared with the FMENV (1991)100 mgl’, WHO (2008)100 mgl’ and USEPA (2005) 100 mgF’ permissible limits. The levels of the Total suspended solids (TSS) were in the range of 0.074 } 0.0051 to 0.077 } 0.0037 mgl’ in the both the wet and dry seasons, these values were within WHO/USEPA, 2005 (0 -5 mgl’) and FMENV, 1991 (30 mgI’) limits. The values of COD ranged from 107.5 } 0.7820 to 134.3 } 4.634 mg (O2)l’ the values obtained were above the maximum permissible limits according to WHO (2008) 10 - 20 mg ’and USEPA (2005)10 Even though the heavy metal pollution were within the maximum permissible limits of NEMA(2004), USEPA (2005), WHO (2008) and FMENV (1991), they are toxic even at very low concentration. Special attention should be paid to mitigate pollution from these sources as their effects may become significant during seasons and years of low water flow in the stream. Therefore, constant monitoring of the Pece stream water quality is needed to record any alteration in the quality and mitigate outbreak of health disorders and the detrimental impacts on the aquatic ecosystem.
A dissertation presented to the college of higher degrees and research Kampala international university Kampala, Uganda in partial fulfillments of the requirements for the degree of master of science in chemistry
Pollution, Heavy metal, Pece channelized, Stream water, Gulu town