Master of Science in Chemistry
Permanent URI for this collection
Browse
Recent Submissions
Now showing 1 - 3 of 3
- ItemAssessment of Water Quality and Selected Heavy Metals in Water, Sediments, and Yams at Masese Landing Site, Lake Victoria, Uganda(2026) Asaba ByaruhangaThis study assessed water quality and contamination focusing on, microbial contamination, heavy metals in water, sediments, locally grown yams at Masese Landing Site on Lake Victoria in Jinja City, Uganda. 60 water and 60 sediment samples were collected from five sites, together with 10 yam samples obtained from two farms, following standard field and laboratory procedures. Physicochemical parameters analyzed were temperature, pH, turbidity, total dissolved solids (TDS), electrical conductivity (EC), and biochemical oxygen demand (BOD₅), while microbial contamination was determined using E. coli and total coliform counts. Heavy metals (Pb, As, Cd, Ni, Cu, Zn, Mn, Cr, and Fe) were analyzed using inductively coupled plasma mass spectrometry (ICP-MS), and Membrane Immediate agar (MI agar) was used for microbial analysis. The results showed that temperature (19.2–20.0°C), pH (7.98–8.22), TDS (411–541 mg/L), EC (767–809 µS/cm), and BOD₅ (0.14–0.16 ppm) were within World Health Organization (WHO) permissible limits (18–24°C, 6.5–8.5, <1000 mg/L, <1500 µS/cm, and ≤5 ppm), indicating minimal risk; however, turbidity ranged from 3.7 to 10.9 NTU, exceeding 5 NTU for WHO. Microbial analysis revealed E. coli counts of 85–195 CFU/100 ml and Total coliforms of 116–226 CFU/100 ml, far above the WHO permissible limit of 0 CFU/100 ml. Heavy metal concentrations in water (mg/L) were Pb (0.353–1.621), Cd (0.109–0.329), Ni (0.089–0.324), Mn (0.086–1.863), and Fe (1.140–12.946), while in sediments (mg/kg dry weight) they were Pb (0.619–1.139), Cd (0.091–0.313), Ni (0.033–0.177), Mn (0.022–1.257), and Fe (3.010–9.306), all exceeding WHO safe limits (Pb ≤0.01, Cd ≤0.01, Ni ≤0.07, Mn ≤0.4, Fe ≤0.3 mg/L). Higher concentrations in sediments confirmed their role as potential secondary contamination sources. Heavy metals were also detected in yam tubers, stems, and leaves, respectively; Pb (3.39, 3.51, 3.56), As (1.80, 1.67, 1.03), and Cd (4.36, 4.40, 3.94) with greater accumulation in leaves than in stems and tubers, indicating bioaccumulation potential and a pathway for human exposure. Health risk assessment using hazard quotient (HQ) indicated values greater than 1 for Pb, As, and Cd, particularly among children, suggesting potential neurotoxic and chronic health effects. Diurnal variations observed in selected parameters and metal concentrations further reflected the influence of environmental conditions and human activities. Overall, although water quality parameters were largely within acceptable limits, the presence of high microbial loads and elevated heavy metal concentrations indicating human health and the ecosystem risks. The study therefore recommends strengthening sanitation practices, routine water quality monitoring and implementation of effective control pollution strategies in the area.
- ItemEffects of Volcanic Activities on The Quality of Domestic Water and Sediments in Goma Town, Democratic Republic of Congo(2025) Shadrack Muhabura ChazigaThe town of Goma, located in the Democratic Republic of Congo near the active volcanoes Nyiragongo and Nyamuragira, faces serious threats to its water quality due to volcanic emissions, ashfall, acid rain, anthropogenic activities and the weak hydraulic infrastructure. This study evaluated the physicochemical parameters (pH, temperature, turbidity, electrical conductivity, TDS, TSS, TH, DO), selected heavy metals (As, Pb, Cd, Cr, Cu, Ni, Zn, Mn), associated health risks, and pollution sources in domestic water, and rainwater of Goma Town. Measurements of physical chemical parameters were made using an AZ 86021 multimeter; while the heavy metals were quantified with a Zeeman Agilent 280Z AA GFAAS furnace. Risks to human health were assessed using the USEPA IRIS model, principal component analyses and hierarchical cluster analyses identified pollution sources. Results revealed alkaline conditions in shore and boreholes samples of water (pH up to 8.6), while rainwater was found to be highly acidic (pH as low as 5.2), highlighting the strong influence of volcanic emissions and acid deposition. Turbidity (ranged from 1.20 to 5.40 NTU) exceeding the WHO limit (<1 NTU) at several sites. Significant contamination by heavy metals was observed, especially forAs (1.471 mg/L), Cd (0.904 mg/L), and Pb (1.301 mg/L), as compared to the limits set by the USEPA (0.05, 0.005 and 0.05mg/Lrespectively). The sediments contained high concentrations of Zn (412 mg/kg) and Mn (268 mg/kg), indicating long-term deposition, as compared to the minimum limits set by USEPA (121 mg/kg for Zinc and 460mg/kg for Mn). The risk assessment indicated hazard quotients greater than 1 for As, Cd, and Pb, which were higher than minimum limits of the USEPA (1). The carcinogenic risk of As (1.9) surpassed the thresholds of the USEPA (<1). The PCA and HCA distinguished geogenic sources (Ni, Cr, Mn) from anthropogenic contributions (Pb, Cd, Zn, Cu).Multivariate analyses distinctly separated geogenic volcanic inputs (Ni, Cr, Mn) from anthropogenic pollution (Pb, Cd, Zn, Cu), emphasizing that water contamination arises from both natural and human sources. These findings underscore the urgent need for targeted management strategies, systematic monitoring, and improved treatment technologies to ensure safe domestic water in Goma and stronger regulatory frameworks to protect public health.
- ItemAssessment of Concentration of Selected Aflatoxins in Maize Flour, Groundnut Seeds and their Detoxifications Using Manganese Peroxidase from Brassica Oleracea (Purple Cabbage) In Kampala City Uganda(2025) Tushabomwe LeonardAflatoxins are harmful secondary metabolites produced by Aspergillus species, presenting significant health complications to both humans and animals when contaminated food is consumed. In Uganda, particularly in Kampala city, there is a high consumption of seeds and or their products like maize flour and groundnut paste, yet the storage of these seeds is not appropriate. Thus, they get contaminated with aflatoxins and there are limited options for detoxification. The aim of this study was to evaluate the concentrations of specific aflatoxins (AFB₁, AFB₂, AFG₁, and AFG₂) in commonly consumed seeds in Kampala city, there is a high consumption of seeds like maize flour and groundnuts, yet contamination with aflatoxins is a critical issue due to inadequate storage conditions and limited options for detoxification. The aim of this study was to evaluate the levels of specific aflatoxins (AFB₁, AFB₂, AFG₁, and AFG₂) in commonly consumed seeds in Kampala and to assess the effectiveness of manganese peroxidase (MnP) extracted from Brassica oleracea (purple cabbage) in neutralizing these aflatoxins. Samples of maize flour and groundnut seeds were collected from local markets and analyzed with High-Performance Liquid Chromatography (HPLC) to measure aflatoxin levels. Manganese peroxidase was extracted from purple cabbage and then applied to samples contaminated with aflatoxins under optimized parameters (pH, temperature, and incubation duration). The effectiveness of MnP in degrading aflatoxins was evaluated by quantifying the residual concentrations after treatment. The findings revealed different degrees of aflatoxin contamination, with total concentrations found in the markets of Nakasero, Kisenyi, Nakawa, Kawempe, and Busega showing aflatoxin concentrations in maize at (44.00 ± 6.57, 28.79 ± 0.53, 1.79 ± 0.04, 3.492 ± 0.09, and 24.027 ± 2.67) ng/g respectively, and in groundnuts at (146.11 ± 8.43, 82.68 ± 5.87, 13.36 ± 2.65, 48.90 ± 4.23, and 19.02 ± 1.04) ng/g respectively, with all samples surpassing the 10ng/g acceptable limits established by the Uganda National Bureau of Standards (UNBS). The MnP derived from purple cabbage showed notable effectiveness in degrading aflatoxins, especially AFB₁, with the solid powdery form of purple cabbage outperforming other enzyme states due to substrate contact efficiency. The cabbage solid extract consistently exhibited the greatest degradation efficiency across all samples (20.0-94.6% for maize; 5.5-30.0% for groundnuts). The liquid extract of MnP displayed moderate effectiveness (15.0-80.2% for maize; 2.7-30.0% for ground nuts), indicating its potential as an affordable and environmentally friendly detoxification solution. This research underscores the necessity for enhanced aflatoxin monitoring in the food supply of Kampala city and recommends enzymatic detoxification as a practical strategy for improving food safety.