Department of Environmental Science
https://hdl.handle.net/20.500.12504/145
2024-03-29T07:26:26ZCompetitive and noncompetitive batch sorption studies of aqueous cd(ii) and pb (ii) uptake onto coffea canephora husks, cyperus papyrus stems, and musa spp. peels
https://hdl.handle.net/20.500.12504/1602
Competitive and noncompetitive batch sorption studies of aqueous cd(ii) and pb (ii) uptake onto coffea canephora husks, cyperus papyrus stems, and musa spp. peels
G. K., Bakyayita; A. C., Norrström; R. N., Kulabako
Coffea canephora, Cyperus papyrus, and Musa spp. were studied for competitive and noncompetitive removal of aqueous Cd2+ and Pb2+. The optimal conditions were pH 4.5 and agitation time 3.0 hours. Biomass constituent ions showed no interference effects whereas cation exchange capacity values corresponded to the sorption efficiencies. XRD spectroscopy revealed surface oxygen and nitrogen groups that provide binding sites for metal ions. The maximum sorption efficiency ranges for metal ions in noncompetitive media were 95.2–98.7% for C. canephora, 42.0–91.3% for C. papyrus, and 79.9–92.2% for Musa spp. and in competitive sorption 90.8–98.0% for C. canephora, 19.5–90.4% for C. papyrus, and 56.4–89.3% for Musa spp. The Pb2+ ions uptake was superior to that of Cd2+ ions in competitive and noncompetitive media. In competitive sorption synergistic effects were higher for Cd2+ than Pb2+ ions.
The pseudo-second-order kinetic model fitted experimental data with 0.917 ≤ 𝑅2 ≥ 1.000 for Pb2+ ions and 0.711 ≤ 𝑅2 ≥ 0.999 for
Cd2+ ions. The Langmuir model fitted noncompetitive sorption data with 0.769 ≤ 𝑅2 ≥ 0.999; moreover the Freundlich model fitted
competitive sorption data with 0.867 ≤ 𝑅2 ≥ 0.989. Noncompetitive sorption was monolayer chemisorption whereas competitive
sorption exhibited heterogeneous sorption mechanisms.
2015-09-01T00:00:00ZAssessment of levels, speciation, and toxicity of trace metal contaminants in selected shallow groundwater sources, surface runoff, wastewater, and surface water from designated streams in lake Victoria Basin, Uganda
https://hdl.handle.net/20.500.12504/1601
Assessment of levels, speciation, and toxicity of trace metal contaminants in selected shallow groundwater sources, surface runoff, wastewater, and surface water from designated streams in lake Victoria Basin, Uganda
G. K., Bakyayita; A. C., Norrström; R. N., Kulabako
The levels, speciation of elements, and toxicity of selected trace metals as well as other parameters in selected surface water, shallow groundwater sources, landfill leachate, and associated surface runoff in the Lake Victoria basin, Uganda, were studied. The WHO guidelines, Ugandan standards, Canadian guidelines and Swedish EPA were used for assessment. The shallow groundwater was acidic with pH values below 6.5. The pH, dissolved organic carbon, flouride, and sulphate levels for all springs were below the guideline values although 52.8% was contaminated with nitrates while 39% was contaminated with chloride ions. Some surface water samples had levels of major elements, such as iron, chromium, aluminium, and manganese, above the guideline values. Speciation studies showed that 74% of the metal ions was bound to dissolved organic matter in surface water, whereas in landfill leachates, the dominant ionic species was metal hydroxides or fulvic acid bound. Risk analysis based on the Swedish EPA showed varied risks of negative effects in 30%–76% of the sample sites ranging from high to increased risk in surface water, whereas the results from modelling sorption data using the Bio-met tool showed potential risk to toxicity effects of Cu2+, Ni2+, Zn2+, and Pb2+ in 15.3%–30.8% surface water samples and 8.3%–62.5% groundwater samples.
2019-05-01T00:00:00ZInvestigating changes in climatic dry conditions across the water management zones in Uganda
https://hdl.handle.net/20.500.12504/1220
Investigating changes in climatic dry conditions across the water management zones in Uganda
Kerudong, Acayerach Paskwale
Prolonged insufficient precipitation associated with evapotranspiration affects
society in various ways such as wilting of crops. Studies with comprehensive
analyses of climatic droughts while considering hydro-climatic differences among
the various Water Management Zones (WMZs) in Uganda are inadequate. This study
addressed this, by extracting extreme climatic indices (ECI) from precipitation and
potential evapotranspiration (PET), characterizing climatic drought across the WMZs
and analyzing connection of variability in the indices to large-scale oceanatmosphere
conditions from 1979 to 2013. Examples of the extracted ECIs included
number of dry days (NDD), number of consecutive dry days, and sum of PET, above
a defined threshold. The long term statistics of the extreme climatic conditions
showed Kyoga and Victoria as the driest and wettest WMZs in Uganda. The extent
and severity of drought were found to depend on the threshold for extracting the
ECIs. Furthermore, the severity of the drought was found to be disproportionate
across the country with the Kyoga and Victoria WMZs being the most and least
severely affected by the impacts of climatic drought. Generally, all WMZs exhibited
decreasing trends in the NDD over the study period, indicating that the country was
becoming wetter recently. Across the country, the Indian Ocean Dipole (IOD) was
negatively correlated with variability of a number of ECIs of both precipitation and
PET. However, correlation between Quasi Biennial Oscillation (QBO) and
variability of several ECIs was generally positive (p<0.05).
Key words: Drought, Climatic Indices, Evapotranspiration, Variability, Trend
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2022-09-01T00:00:00ZImpact of implementation of community-based wetland management plan on the conservation of lake Mulehe wetland in Kisoro, Uganda
https://hdl.handle.net/20.500.12504/1207
Impact of implementation of community-based wetland management plan on the conservation of lake Mulehe wetland in Kisoro, Uganda
Birungi, Kabasharira Joan
Increased encroachment, mismanagement and degradation of wetland resources such as
Lake Mulele in Uganda has called for continuous involvement of surrounding people into
their management. The Ugandan government and other conservation agencies such as
IUCN, Wetland Management Department have encouraged the implementation of
CBWMPs since 1992. This study’s objective was therefore to determine the impact of
Community Based Wetland Management Plan on conservation of Lake Mulehe wetland in
Kisoro, South Western Uganda. The study ascertained land cover changes in Lake Mulehe
wetland, examined impacts of CBWMP on community perceptions and practices towards
wetland conservation and established the emerging threats to the conservation of L. Mulehe
wetland. The study undertook both qualitative and quantitative research designs that
included observational survey methods, household interview, FDGs and Key informant
interviews. Land cover analysis identified seven (7) key land cover types (Built up, forest,
tea plantation, woodland, bush land, and subsistence farming). A small increment of 0.07%
in wetland land cover between 2004 and 2018 with subsistence and bushland taking a front
case with 64.04% and 11.20% respectively was also observed. L. Mulehe CBWMP
positively influenced the conservation perceptions and practices of the surrounding
communities thus 68% respondent agreed that there was improvement in vegetation, water
and soils although the imagery analysis revealed otherwise. A 86.7% correlation between
age of respondents and participation in conservation activities also confirm a positive
impact of CBWMP on the wetland. The CBWMP has also boosted the conservation status
of L. Mulehe. In addition, CBWMP has influenced conservation of L. Mulehe wetland
through perception change. Such positive impacts of CBWMP in Mulele can be used by
both NEMA and Ministry of water and environment in enhancing conservation of wetlands
in other areas among different community members.
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2022-09-01T00:00:00Z