Browsing by Author "Mbabazi, Jolocam"

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    Contamination by heavy metals in silver fish (Rastreneobola argentea) caught from Lakes Kyoga and Victoria, Uganda
    (International Journal of Environmental Studies, 2010) Mbabazi, Jolocam; Wasswa, John
    Little information exists on heavy metal contamination in silver fish (Rastreneobola argentea) caught from Lake Victoria. A large number of Ugandans consume the species. Sun-dried silver fish were collected from 10 landing sites on Lake Victoria, and from five control sites along Lake Kyoga. The finely ground fish was digested with analytical reagent grade nitric acid. Analyses were performed by atomic absorption spectrophotometry. The specimens were found to contain significantly higher levels (p ≤ 0.05) of zinc, Zn (86.1%), copper, Cu (99.1%), cadmium, Cd (99.3%) and lead, Pb (94.6%) compared with those from the control sites. The fish contamination was attributed to discharge into Lake Victoria of untreated industrial and anthropogenic effluent. Although mean Zn, Cu and Pb concentrations were still below, those of Cd were higher than the maximum permissible levels recommended by the World Health Organization (WHO). Overconsumption of the silver fish could pose Cd-related health risks.
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    Equilibrium and Kinetic Studies of the Stannate(Iv)-Polyol Reaction
    (Chemical Society of Ethiopia, 2010) Mbabazi, Jolocam; Wasswa, John; Ntale, Muhammad
    The stability constants of 1:1 stannate(IV)-polyol complexes in aqueous media have been determined using a conductimetric technique. The constants are fairly large, and lie in the range 5.3-123.0 for the ten ligands investigated. These values were subsequently used in conjunction with kinetic data to postulate a mechanism involving the species Sn(OH)5 as intermediate in the formation of the chelates. The stannate(IV)- polyol reaction, though taking place at higher pH values, is acid-catalysed and follows first-order kinetics in the oxyanion, but at large ligand-oxyanion mole ratios the reaction exhibits zero-order rate dependence on the polyol. These features taken together are consistent with a unimolecular nucleophilic substitution on the oxyanion.
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    Heavy metal contamination in vegetables cultivated on a major urban wetland inlet drainage system of Lake Victoria, Uganda
    (International Journal of Environmental Studies, 2010) Mbabazi, Jolocam; Wasswa, J.; Kwetegyeka, J.; Bakyaita, G.K.
    The population of the Ugandan capital, Kampala, located close to Lake Victoria, appears to be exposed to risk of ingesting the heavy metals Cadmium (Cd) and Lead (Pb) through vegetables in their diet. Lake Victoria is responsible for frequent torrential polluted runoffs in the city. The Nakivubo channel, the city’s major wetland drainage system, empties directly into the lake. Vegetables are grown on the urban wetland soils. Heavy metal content in vegetables from the wetland cultivation sites was determined by wet acid digestion, with 87–92% recovery. The results showed that although the heavy metal levels of manganese (Mn), zinc (Zn), cadmium (Cd) and lead (Pb) were significantly higher than those in similar food crops from rural control sites, only Cd and Pb exceeded the World Health Organisation (WHO) maximum permissible levels. Cd and Pb pose serious human health risks. Early pollution control measures are advisable.
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    Organochlorine pesticide residues in sediments from the Uganda side of Lake Victoria
    (Chemosphere, 2011) Wasswa, John; Kiremire, Bernard T.; Nkedi-Kizza, Peter; Mbabazi, Jolocam; Ssebugere, Patrick
    Organochlorine (OC) residues were analysed in 117 sediment samples collected from four bays of the Uganda side of Lake Victoria. The sediments were collected with a corer at a depth of 0–20 cm, and extracted for OC residues using a solid dispersion method. The extracts were cleaned using gel permeation chromatography and analysed for pesticide residues using a gas chromatograph (GC) equipped with an electron capture detector. The results were confirmed using a GC equipped with a mass spectrometer (MS). A total of 16 OC residues, most of them persistent organic pollutants (POPs) were identified and quantified. The OC residue levels were expressed on an oven dry weight (d.w.) basis. Endosulphan sulphate, in the range of 0.82–5.62 lg kg 1 d.w., was the most frequently detected residue. Aldrin and dieldrin were in the ranges of 0.22–15.96 and 0.94–7.18 lg kg 1 d.w., respectively. DDT and its metabolites lay between 0.11–3.59 for p,p0-DDE, 0.38–4.02 for p,p0-DDD, 0.04–1.46 for p,p0-DDT, 0.07–2.72 for o,p0-DDE and 0.01–1.63 lg kg 1 d.w. for o,p0-DDT. The levels of c-HCH varied from 0.05 to 5.48 lg kg 1 d.w. Heptachlor was detected only once at a level of 0.81 lg kg 1 d.w., while its photo-oxidation product, heptachlor epoxide, ranged between non-detectable (ND) to 3.19 lg kg 1 d.w. Chlordane ranged from ND to 0.76 lg kg 1 d.w. Based on the threshold effect concentration (TEC) for fresh water ecosystems, aldrin and dieldrin were the only OCs that seemed to be a threat to the lake environment.
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    Organochlorine pesticides in soils from south-western Uganda
    (Chemosphere, 2010) Ssebugere, Patrick; Wasswa, John; Mbabazi, Jolocam; Nyanzi, Steven A.; Kiremire, Bernard T.; Marco, John A.M.
    Organochlorine (OC) residues were analysed in soil samples collected from Kihiihi sub-county, Kanungu District, which is located in south-western Uganda. Mabira Central Forest Reserve which is located in central Uganda was used as a reference site in this study. The samples were collected at 15–20 cm depths below the soil surface and extracted with organic solvents. The extracts were cleaned using florisil, and were analysed using a gas chromatograph (GC) equipped with an electron capture detector (ECD). The results were confirmed using a GC equipped with a mass spectrometer (MS). The levels of the OC residues in soil from Kihiihi sub-county varied from non-detectable (ND) to 59 μg kg−1 dry weight. The frequencies of detection for p,p′-DDT, p,p′-DDE and p,p′-DDD in the total soil samples were 47%, 24% and 11%, respectively. The o,p′compounds were detected in the following frequencies: o,p′-DDT (23%), o,p′-DDE (19%) and o,p′-DDD (8%). The low p,p′-DDE/p,p′-DDT residue ratios (0.2–0.9) in Kihiihi samples suggest recent inputs of DDT in Kihiihi sub-county. The detection frequencies for dieldrin, endosulfan-α, -β and -sulphate in the soil samples were 21%, 26%, 31% and 19%, respectively. Mabira Forest Reserve soils showed detection frequencies of p,p′-DDT (5%) and p,p′-DDE (9% of the soil samples), varying from ND to 9 μg kg−1. Although the use of OCPs has been banned, our results show that they can still be detected in the environment. Their presence may be attributed to adulteration of pesticides which are not banned and also atmospheric deposition.
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    Speciation of heavy metals in water from the Uganda side of Lake Victoria
    (International Journal of Environmental Studies, 2010) Mbabazi, Jolocam; Twinomuhwezi, H.; Wasswa, J.; Ntale, M.; Mulongo, G.; Kwetegyeka, J.; SchrǾder, K.H.
    Different forms of copper Cu, zinc Zn, lead Pb and cadmium Cd in water from the Uganda side of Lake Victoria (25°C, pH 6.75–7.18), the second largest inland freshwater lake in the world, have been studied using ion-exchange, dialysis and atomic absorption spectrophotometry. The results indicate that heavy metals Cu, Zn, Pb and Cd are present mainly in the cationic form (80–83%). Small quantities of anionic (13–22%), non-ionic, dialyzable (4–8%), and non-ionic, non-dialyzable (< 1.3–4.4%) forms were also detected for all metals except Cd. The corresponding concentrations lay in the ranges: cationic, 0.06–0.99; anionic, < 0.001–0.25; non-ionic, dialyzable, < 0.001–0.08; non-ionic, non-dialyzable, < 0.001–0.06 μg ml−1. The existence of the metals in non-ionic and nondialyzable forms is attributable to metal associations with high relative molecular mass (RMM) organic matters.
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    Trace Elements in Marketed Rastreneobola Argentea and Clarias Werneri Caught from Selected Aquatic Ecosystems in Uganda
    (International Journal of Current Trends in Engineering and Technology, 2015) Nnamuyomba, Proscovia; Mbabazi, Jolocam; Ntale, Muhammad
    Samples of two fish species Rastreneobola argentea and Clarias werneri from Lake Victoria, Lake Kyoga and Nakivubo and Lubigi wetlands were analysed for Cu, Zn, Pb and Cd using an Atomic Absorption Spectrophotometer - Perkin-Elmer Model 2380. The results revealed that Zn concentrations were the highest in both species, followed by Cu; Pb and Cd being the lowest. The concentrations of Cu, Zn, Pb and Cd in R. argentea from Lake Victoria ranged between 20.5- 115 µg/Kg, 175 - 495 µg/kg, 15 -77.5 µg/Kg and 2.5 - 4.45 µg/kg respectively, mean while their concentrations in the same fish species from Lake Kyoga ranged between 12.5 - 37.5 µg/kg (Cu), 35-100 µg/kg (Zn), 5-12.5 µg/kg (Pb), 0.5-1.5 µg/kg (Cd) dry weight. In C.werneri, heavy metals varied between 197-337.5 µg/kg (Cu), 235-670 µg/kg (Zn), 60-77.5 µg/kg (Pb) and 2.5-6.98 µg/kg (Cd) in Lubigi wetland and in Nakivubo wetland, concentrations of heavy metals ranged between 752- 1320 µg/kg for Cu, 1230-1437 µg/kg for Zn, 85-97.5 µg/kg for Pb and 2.2-7.75 µg/kg for Cd. Heavy metal concentrations obtained in this study were below permissible limits issued by WHO/FAO. Therefore, the consumption of these fish species may not pose any threat to human health. However periodic monitoring of these metals in the fish caught from water bodies located in urban areas is highly essential to public health.
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    Variations in the contents of heavy metals in arable soils of a major urban wetland inlet drainage system of Lake Victoria, Uganda
    (Lakes & Reservoirs: Research & Management, 2010) Mbabazi, Jolocam; Bakyayita, Grace; Wasswa, John; Muwanga, Andrew; Twinomuhwezi, Hannington; Kwetegyeka, Justus
    Little is known about the effects of urbanization on the chemical quality of soils in suburban wetland inlet drainage systems to the Uganda side of Lake Victoria, on which food crops are extensively grown. It is feared that pollution in the soils might eventually enter food chains through such crops being consumed by urban populations unaware of their occurrence. Soil samples were collected from cultivated areas of a major wetland drainage system (Nakivubo Channel), at Kampala, Ubanda, near Lake Victoria and from a rural control wetland site (Senge). The soil from this site had similar properties as those from the urban test site (i.e., soil texture; porosity; humus content). Analysis of heavy metals with atomic absorption spectrophotometry (AAS) yielded the following soil concentration ranges: manganese (190–780), cadmium (<0.001–1.0), zinc (6.0–10.0) and lead (10–20 mg kg)1) dry weight for the control site, and 450–900, 1.0–2.0, 131– 185, 40–60 mg kg)1 dry weight, respectively, for the urban wetland, indicative of relatively heavy metal pollution in the suburban drainage system. Heavy metal levels in cocoyam (Colocasia Esculenta) and sugarcane (Saccharum Officinarum) grown on both wetland soils also were evaluated via AAS with a modified wet-acid-digestion technique. The results highlighted high cadium and lead levels (P £ 0.0003) in the crops from urban wetland cultivation. Cadmium and lead concentrations in cocoyam from urban wetland soils exceeded those from the control site by 0.17 and 3.54 mg kg)1, respectively. The corresponding results for sugarcane indicated a similar increase of 0.56 and 2.14 mg kg)1 of juice extract. Cadmium and lead levels in both urban wetland crops were higher than the maximum permissible limits of the Codex Alimentarius Commission, indicating that these concentrations pose potential health risks to urban consumers, and call for early counter-measures to combat urban pollution entering the lake.