Browsing by Author "Ntambi, Emmanuel"
Now showing 1 - 10 of 10
Results Per Page
Sort Options
Item Analysis for Organochlorine Pesticide Residues in Honey from Kabale District, South-Western Uganda(American Journal of Analytical Chemistry, 2019) Ntirushize, Benon; Wasswa, John; Ntambi, Emmanuel; Adaku, ChristopherThis study was motivated by the reported accumulation of Organochlorine Pesticides (OCPs) residues in the various environmental matrices within Uganda, resulting from their use in agriculture and health sectors. This raised a concern of the likelihood of the accumulation of the OCPs residues in the honey produced within the country which would affect its purity as well as quality and consequently its competition on the world market. Sixty representative honey samples were collected from selected local beekeepers from four sampling stations in Muko sub-county, Kabale, and extracted for OCPs using a solid-phase procedure followed by a florisil column packed clean-up method and Gas Chromatography-Electron Capture Detector (GC-ECD) analysis. Confirmation of the selected samples was done using an Agilent (6890N, USA) gas chromatograph combined with a mass spectrometer. Recoveries of spiked samples ranged from 71% to 96%, except for pp-DDE (54%), with relative standard deviations from 2% to 14% in terms of repeatability, and from 4% to 17% in terms of reproducibility. Limits of quantification were from 0.003 to 0.1 mg∙kg−1. Endosulfan sulfate was the most frequently detected in 38% of the samples, followed by HexaChloroBenzene (Lindane) in 21% of the samples. Residues of DDT and their metabolites were detected in 17% of the samples. Mean concentrations of the pesticide residues detected range from ND (not detected) to 1.53 μg/Kg. The acceptable Maximum residual limits (MLRs) are 200 - 300 μg∙kg−1 fresh weight for dieldrin, 500 μg∙kg−1 for DDT and break down products, and 50 μg∙kg−1 wet weight for Lindane (WHO/FAO 2011). Results indicate that the levels of OCP residues detected in honey from the country’s South Western District of Kabale were within the acceptable limits, and hence this honey was safe for human consumption.Item Assessment of Seasonal Variation in Water Quality in River Rwizi Using Multivariate Statistical Techniques, Mbarara Municipality, Uganda(Journal of Water Resource and Protection, 2017) Ojok, Walter; Wasswa, John; Ntambi, EmmanuelAssessment of seasonal variations in surface water quality characteristics is an essential aspect for evaluating water pollution due to both natural and anthropogenic influences on water resources. In this study, temporal variations of water quality in river Rwizi section within Mbarara municipality, Uganda, were assessed using multivariate statistical methods. This river section is a major source of water for the inhabitants of Mbarara municipality. Water samples from five sites were analyzed for physicochemical parameters such as pH, EC, turbidity, temperature, TSS, TDS, alkalinity, salinity, colour, NH3-N, 24 SO − , total hardness, BOD, COD, DO, Ca, Mg, Fe, and Mn. About 50% of sites recorded colour above 800 Pt Co, 60% of sites recorded turbidity above maximum permissible limit of 100 mg/l, attributable to erosion and mineral matter. pH for dry season ranged between 6.5 and 8.5 whereas for rainy season was below 6.0. All study sites recorded total Fe above 0.3 mg/l and Mn below 0.5 mg/l, attributable to chemical weathering of host rock materials as well as from industrial effluent. About 60% of sites recorded COD above 100 mg/l, 40% and 80% of study sites showed BOD above 50 mg/l in dry and rainy seasons respectively. Hardness ranged between 50 and 100 mg/l indicating that the water is moderately soft. Colour, turbidity, alkalinity, TSS, TDS, salinity, pH, hardness, Fe, Mn, NH3-N, BOD, COD, and DO were higher in rainy season, as a result of erosion, discharge of domestic and industrial waste. Mg, Ca, and 2 4 SO − were higher during dry season due to high evaporation of water from the river. PCA/FA determined that 81.2% of the total variance was explained by the first factor for the dry season and 69.2% for rain season. These results revealed that water pollution resulted primarily from domestic waste water, agricultural runoff and industrial effluents.Item Heavy Metal Bioaccumulation by Maize Grown on a Ferralsol Amended with Urban-Based Biosolid Wastes(Journal of Agricultural Chemistry and Environment, 2021) Ntambi, Emmanuel; Ntale, Muhammad; Tenywa, John StephenOrganic waste materials as soil amendments are one of the topical approaches applauded for achieving sustainable agriculture world-over. The objective of this study was to investigate the effect of urban-based biosolid waste (UBBW) application on heavy metals (Cr, Cu, Zn and Pb) bioaccumulation by maize (Zea mays L.) plants. A pot experiment was conducted three times, using an acid Ferralsol from Makerere University Agricultural Research Institute, Kabanyolo (MUARIK) in Uganda. Treatments included the application of three types of UBBW, namely sewage, brewery and abattoir, each applied independently at the rates of 0, 50 and 100 g per pot filled with 4 kg soil. This was equivalent to 0, 2.5 and 5.0 metric tonnes of dry materials per hectare. Phosphorus fertiliser was also applied at 0, 0.795 and 1.591 g P per pot, equivalent to rates of 0, 25 and 50 kg P ha-1. The brewery waste applied at rates ≥ 2.5 t·ha-1 and phosphorus at 25 kg P ha-1 resulted in shoot Cu concentrations below the World Health Organisation (WHO) safe limit (73.3 mg·kg-1); and Zn slightly above the WHO safe limit (99.4 mg·kg-1). In contrast, the concentrations of chromium in the maize plants were well above the WHO safe limit (2.3 mg·kg-1), irrespective of the applied type of UBBW. Shoot metal bioaccumulation followed the order zinc > copper > chromium, with Pb being below the detection limit. The safest UBBW was abattoir waste; while the least environmentally suitable was sewage waste. It is clear that irrespective of the type of UBBW, their application to Ferralsol causes less bioaccumulation of Pb and Cr in maize plants compared to Zn and Cu.Item Hydrochemistry and fluoride contamination in Ndali-Kasenda crater lakes, Albertine Graben: Assessment based on multivariate statistical approach and human health risk(Groundwater for Sustainable Development, 2021) Ojok, Walter; Wanasolo, William; Wasswa, John; Bolender, James; Ntambi, EmmanuelHydrochemistry of crater lakes (n = 15) in the Ndali-Kasenda cluster was deciphered using standard methods of the American Public Health Association to understand the major ion chemistry; spatial distribution, occurrence, and non-carcinogenic health risks due to exposure to fluoride levels in the lakes in Ndali- Kasenda cluster, Albertine Graben. Numerous economic activities take place in and around the crater lakes which serve as major sources of domestic water whose origin of potential contaminants is ambiguous. In this study, WHO (2017) regulatory limit exceedance included F , pH, Ca2+, Fe2+, Mn2+, and TDS. A strong positive correlation was observed between F and TDS; F and pH; F and EC; F and HCO3 . However, concerning hydrogeochemical signature, the lakes are mainly of Ca–HCO3 type and low in Na–K–HCO3 type due to rock water interaction in the geology of the area. Principal component analysis (PCA) performed on Ndali-Kasenda hydrogeochemical data resulted in six principal components (PCs) explaining 88.6% of the total variance. The PCs represented the primary processes that control the crater lake hydrogeochemistry in the Ndali-Kasenda area which include; weathering of rocks reactions, ion exchange, and evaporation processes. The hazard quotient (HQ) for noncarcinogenic health risks associated with exposure to Ndali- Kasenda fluoride levels via ingestion revealed that HQ for infants surpassed the acceptable HQ limit for all the lakes studied, while 86.67 % of the sampled lakes exceeded the HQ value for children via ingestion. Based on the hydrogeochemical parameters analyzed, aside from L. Murigamire and L. Wankenzi, water from the other studied lakes is chemically not acceptable for drinking purposes. An urgent need to take ameliorative action in this area to protect the inhabitants from exposure to excess fluoride in drinking water was recommended.Item Mobility of Chromium, Copper and Arsenic in Amended Chromated Copper Arsenate Contaminated Soils(Asian Journal of Applied Chemistry Research, 2020) Kiwanuka Nakiguli, Caroline; Ojok, Walter; Omara, Timothy; Wasswa, John; Ntambi, EmmanuelThe use of copper-based preservatives such as chromated copper arsenate (CCA) and creosote to prolong the life of lumber present environmental concerns because they contain heavy metals and polycyclic aromatic hydrocarbons which are toxic to humans. The aim of this study was to investigate the effects of sewage sludge biosolid amendment on the distribution and mobility of chromium, copper and arsenic in chromated copper arsenate contaminated soils subjected to phytoremediation using maize (Zea mays L.). Place and Duration of the Study: Random composite soil samples from Kitetika wood factory, Wakiso, Uganda and sewage sludge biosolid from National Water and Sewerage Corporation plant in Bugolobi, Kampala, Uganda were collected and prepared. Maize grains were obtained from FICA Seeds Limited (Uganda). The pot experiments and analysis of samples were done at Mbarara University of Science and Technology (Mbarara) and Directorate of Government Analytical Laboratory, Kampala (Uganda), respectively. Methodology: The fresh CCA contaminated soils and sewage sludge biosolid were analyzed for physicochemical parameters and heavy metals (chromium, copper and arsenic). Sewage sludge biosolid was added to 1 kg of the contaminated soils at 5-25% (w/w) in 2 L plastic containers, watered and maintained at 25 ℃ for 14 days to stabilize. Controls were set up with unamended soils. Thereafter, maize was planted in the potted soils for 40 days. The concentrations of the trace metals in the soils were determined after 20 and 40 days of maize growth by atomic absorption spectroscopy. Results: The concentrations of chromium, copper and arsenic in fresh CCA contaminated soils were 365.8 ± 6.18 mg/kg, 109.72 ± 14.04 mg/kg and 28.22 ± 3.8 mg/kg, respectively. Basing on mobility factor, bioavailability of the trace metals followed the chemical sequence copper (8.9%) < chromium (17.1%) < arsenic (30.2%). Conclusion: The maize variety experimented could be used to phytoextract or phytostabilize the trace metals in the CCA contaminated soils without or with 5-25% amendment. Amendment with sewage sludge biosolid improved the phytoremediation potential of maize. Arsenic was the most mobile and bioavailable metal in CCA contaminated soils. Further studies should use other local maize varieties such as Longe series.Item Physicochemical quality of water from Chuho springs, Kisoro district, Uganda(2021) Nkurunziza, Gerald; Omara, Timothy; Nakiguli, Caroline Kiwanuka; Mukasa, Paul; Byamugisha, Denis; Ntambi, EmmanuelIn the current study, water from Chuho springs used as the main water source in Kisoro municipality, Uganda were assessed for their suitability as drinking water. The temperature, turbidity, conductivity, total dissolved solids, dissolved oxygen, biological oxygen demand, total hardness, total alkalinity, calcium, magnesium, phosphates, iron, copper, arsenic, chlorides and the fluoride content of the water samples were determined. Not all the parameters met World Health Organizations’ guidelines for drinking water. Temperature, dissolved oxygen and fluorides were outside the recommended limits of 15 ℃, 10-12 mg/L and 1.5 mg/L, respectively. Further studies should assess the microbiological and sanitary profile of the springs. __________________________________Item Pollution Status, Source Apportionment, Ecological and Human Health Risks of Potentially (Eco)toxic Element-Laden Dusts from Urban Roads, Highways and Pedestrian Bridges in Uganda(Cham: Springer International Publishing, 2021) Opolot, Mark; Omara, Timothy; Adaku, Christopher; Ntambi, EmmanuelThe occurrence of potentially (eco)toxic elements (PTEs) in street, indoor and roadside dusts have been associated with potential human health risks. For the first time, the pollution levels of PTEs—copper (Cu), nickel (Ni), manganese (Mn), zinc (Zn), lead (Pb), cadmium (Cd) and chromium (Cr)—were investigated in 24 dust samples from eight selected sampling sites on urban roads, highways and pedestrian bridges constructed over River Manafwa, a flood-prone river in Eastern Uganda. Concentration of PTEs in the sample digests were quantified by atomic absorption spectrometry. Multivariate geostatistical (Pearson’s Correlation, Principal Components and Hierarchical Cluster) analyses were used to apportion sources of the contaminants. Contamination, ecological and human health assessment indices and models were employed to establish any potential risks the elements could pose to the environment and humans. The study revealed that there is severe PTE pollution of dusts from roads, highways and pedestrian bridges in Eastern Uganda when compared with their crustal averages, except for Cu, Ni and Cr. The mean concentrations (mg kg1) of Cu (11.4–23.2), Ni (0.20–23.20), Mn (465.0–2630.0), Zn (26.8–199.0), Pb (185.0–244.0), Cd (0.178–1.994) and Cr (5.40–56.60) were highest in samples obtained near high-traffic areas. Source apportionment studies suggested that Cu, Ni, Mn and Cr are from combustion processes and vehicular traffic, whereas Pb, Zn and Cd came from traffic and geogenic contributions. Assessment using the pollution load index indicated that only dust from Zikoye–Bushika road, the junction of Zikoye–Bushika and Bududa–Manafwa roads and Manafwa town were substantially polluted as the indices were greater than 1. Further assessment of pollution degree of the dust samples using index of geo-accumulation revealed that the dusts were practically uncontaminated to medium-to-strongly contaminated. Health risk assessment showed that there are non-carcinogenic health risks that could emanate from direct ingestion of PTEs in dusts by children. This study therefore opens the lead for investigation of the contamination levels and the health risks of PTEs in dusts from industrial areas as well as busy Ugandan cities such as Kampala, Jinja, Mbarara and Gulu.Item Spatial Variation in Physicochemical Surface Water Quality in River Rwizi, Western Uganda(Journal of Water Resource and Protection, 2019) Walter, Ojok; Wasswa, John; Nakiguli, Caroline K.; Ntambi, EmmanuelRiver Rwizi originates from the Buhweju hills. It is a major source of water for the inhabitants of Mbarara Municipality and surrounding environment. In this study, spatial variation of water quality in River Rwizi section within Mbarara Municipality was determined using cluster analysis. Laboratory analysis was conducted on water samples from five sites along the river section using standard methods for: pH, EC, TSS, TDS, turbidity, temperature, total hardness, alkalinity, salinity, colour, NH3-N, 24 SO − , BOD, COD, DO, Ca, Mg, Fe, and Mn. Cluster analysis grouped the study sites into slight pollution (Spencon, GBK), moderate pollution (Katete) and high pollution (BSU, Kakoba) for dry season. For rain season, order was: slight pollution (BSU, Spencon), moderate pollution (GBK) and high pollution (Kakoba, Katete), basing on similarity of water quality variables. These results show that water pollution resulted primarily from domestic waste water, agricultural runoff and industrial effluents. Thus, water from River Rwizi is not suitable for drinking in both dry and wet seasons.Item Spatio-temporal Variations and Potential Health Risks of Heavy Metals in Water from River Manafwa, Uganda(Letters in Applied NanoBioScience, 2022) Opolot, Mark; Omara, Timothy; Adaku, Christopher; Ntambi, EmmanuelThe epicenter of flash flood inundations and landslides in Uganda have been areas around Mt. Elgon. By implication, it has led into loss of lives, food and water insecurity. This study assessed the seasonal variations in physiochemical parameters and heavy metals (HMs) content of water from River Manafwa (R. Manafwa) which is the major water source used around Mt. Elgon. Potential insidious human health risks associated with consumption and dermal contact with water from the river were assessed using target hazard quotient and incremental lifetime cancer risk methods. Results of atomic absorption spectrometry analysis showed that the concentrations of the HMs in the wet and dry seasons ranged from below detection limit to 1.407 ± 0.001 mg/L, which were below WHO limits. Health risk assessments indicated that there are discernable non-carcinogenic health risks from ingestion of water from R. Manafwa, as the total target hazard quotients were above 1 for some of the samples. Cancer risk values indicated that there are no potential cancer risks from ingestion of water from the river. This study recommends that regulatory authorities should intervene to mitigate pollution of R. Manafwa through strengthening restrictions on sand mining and dumping of wastes into the river.Item Synthesis and characterization of hematite biocomposite using cassava starch template for aqueous phase removal of fluoride(Carbohydrate Polymer Technologies and Applications, 2022) Ojok, Walter; Ntambi, Emmanuel; Bolender, James; Wasswa, John; Wanasolo, William; Moodley, BrendaIn this study, facile synthesis of α-Fe2O3 biocomposite was mediated by cassava starch as a soft template. Batch mode evaluated its sorption behavior for fluoride removal from aqueous media. Characterization studies using analytical techniques confirmed the existence of porous α- Fe2O3 biocomposite with heterogeneous surfaces having a varied affinity for fluoride. The sorption process was optimized using central composite design (CCD) in response surface methodology (RSM) with a good model prediction (R2 = 0.9066). A study of the interaction effect showed the synergy of process variables on fluoride removal with the result’s intensity indicated by the nature of contour plot curvature. Based on the RSM optimization, an optimum fluoride removal efficiency of 85.26 % can be achieved at an initial fluoride concentration of 55 mg/L, α- Fe2O3 biocomposite dose of 0.55 g, pH of 7.5, and contact time of 95 min. Sorption equilibrium data were well modeled by Freundlich isotherm (0.9916), indicating multilayer sorption on a heterogeneous surface of the sorbent with a varied affinity for fluoride. Presence of co-existing anions reduced fluoride removal efficiency in the order PO43 > HCO3 > SO4 2 > NO3 > CƖ . At the same time, its kinetics was better modeled by pseudo-second-order kinetics (R2 = 0.9764), showing that the sorption process is rate-limiting. The sorption thermodynamics study showed that the process was spontaneous, exothermic, and entropy-driven physisorption. Hence, the results signify that the green synthesized α- Fe2O3 biocomposite could be a potential sorbent for sustainable defluoridation.