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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
71

Microbiological assessment of water quality and prevalence of waterborne diseases in rural areas of Masaka, Rwanda

Uwimpuhwe, Monique 28 May 2014 (has links)
Submitted in fulfilment of the requirements for the Master of Technology Degree: Environmental Health, Durban University of Technology, 2012. / Waterborne diseases represent substantial global burden of disease and children under the age of five are more susceptible to these diseases compared to adults. The aim of this study was to determine the microbiological quality of Nyabarongo River water used for domestic purposes, women’s knowledge, attitudes and practices (KAP) on water usage and waterborne diseases and its link to the diarrhoea outbreaks experienced in two rural communities: Rusheshe and Ayabaraya of Masaka in Rwanda. A total of 35water samples were collected from Nyabarongo River and from study households which used slow sand filtration (SSF) or Sûr’Eau as treatment methods and analyzed for total coliform and faecal coliform indicators. For household samples turbidity was also analyzed. Retrospective records from Masaka Health Centre were reviewed to determine the prevalence of waterborne diseases from the study areas during 2010. Further, a structured questionnaire was administered to 324 women residents of the study areas to elicit information on their KAP on water handling and waterborne diseases. SPSS Predictive Analytic Software (PASW) Statistics version 18.0 (IBM, Somers, NY) and STATA Release (Version 11.0, College Station, Texas USA) were used for data analysis. Results showed that the mean values of total and faecal coliforms of river and household water samples were above the WHO and Rwandan recommended guidelines. The mean values of total coliform and faecal coliform were significantly lower (p ≤ 0.05) in both filtered and Sûr’Eau treated water than in river water. No statistical differences of means were observed for both total coliform and faecal coliform counts between samples taken from filtered and Sûr’Eau treated water containers (p=0.80 (TC) and p = 0.56 (FC). However, turbidity values were significantly lower in filtered water using SSF than in Sûr’Eau treated water samples (p =0.002). Out of 2814 records form Masaka Health Centre during 2010, 160 cases were identified as having diarrhoeal diseases. Furthermore, respondents who used Nyabarongo River as source of water were more likely to have symptoms of diarrhoea (OR =5.35; CI: 2.12 - 14.46; p <0.05). The frequency of diarrhoea were significantly higher among people who did not wash hands before food preparation (p = 002) and after using a toilet (p = 0.007) than among those who did. There was a statistically significant association of level of education levels and drinking water treatment practices at the household level (p < 0.05). Respondents with primary school education only and those with high school education were more likely to wash their hands after using a toilet (OR= 5.24, CI 1.42-19.38, p =0.01 and OR = 7.15, CI = 1.79 -28.62, p=0.01, respectively) than those who did not attend school. No significant associations were identified between educational levels and washing hands before food preparation. The findings of this study points to the facts that water sourced from Nyabarongo River is unsafe for human consumption even after prescribed treatment, such as the use of SSF and Sûr’Eau, and could increase the prevalence of waterborne diseases and therefore calls for urgent provision of potable water. Women in the study areas had limited knowledge regarding water storage practices for prevention of household water contamination and this; underscore the need for more water handling practices and hygiene education in rural communities. / Durban University of Technology.
72

Scale-dependent effects of spatial and temporal variability on benthicmacroinvertebrate communities in Hong Kong streams

梁士倫, Leung, Sze-lun. January 2002 (has links)
published_or_final_version / Ecology and Biodiversity / Doctoral / Doctor of Philosophy
73

The impacts of harmful algal blooms on a Florida reef fish community

Unknown Date (has links)
Coral reefs worldwide are threatened by many environmental disturbances including harmful algal blooms (HABs) which have been increasing on Florida coasts over the past decade. Research has mainly focused on HAB identification, percent cover and other effects on the benthos but the relationship of HABs with upper trophic levels has received less attention. To study this relationship, a two-year investigation on a 10-m deep reef off of Hallandale Beach, was conducted. Stationary fish census coupled with benthic transect videos were conducted quarterly between April 2005-July 2007. A significant correlation between Lyngbya sp. blooms and alterations in fish assemblages was observed. Lyngbya had a negative interaction with fish species and abundance; additionally, HAB sample periods were significantly different from low algal abundance periods. Blooms of Dictyota sp. had no measurable relationship with the fish assemblage indicating HABs may have variable impacts on fishes depending on family, species and chemistry of the algae. / by Rex E. Baumberger, Jr. / Thesis (M.S.)--Florida Atlantic University, 2008. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2008. Mode of access: World Wide Web.
74

Water Quality Indicators in Watershed Subbasins with Multiple Land Uses

Aull, Malia Elizabeth 03 May 2005 (has links)
The wide use and accessibility of surface waters leads to multiple sources of contamination. The two main forms of pollution are from point and nonpoint sources. Point sources are regulated by the federal government; however, nonpoint sources are more difficult to regulate since there is no defined origin. Due to this problem, surface water monitoring is performed by state agencies which can include the testing of several different water quality indicators chosen by the state. This thesis examines several water quality indicators from two watershed subbasins with different land uses. The types of contamination and sources were evaluated from the data, which was analyzed based on sampling site, season, and two statistical tests. The water quality indicators that were examined in this study included physical, chemical, and microbiological indicators. The two subbasins that were monitored were located in the Wachusett reservoir watershed in central Massachusetts. One subbasin, Malagasco Brook, was located south of the reservoir. Six sampling sites were chosen in proximity to a swampy area, a nursery, and condominium housing complex. The second subbasin, Beaman Pond, was located to the northwestern side of the reservoir and was monitored at three sites. These sites were located in a residential area in addition to a special use two acre farm. Analyses were performed by site and by season to find trends in the data. Statistical correlation and ANOVA analyses were performed in order to better understand the relationships of the water quality indicators. From these analyses, it was determined that organic carbon and human sources of contamination were significant in the Malagasco Brook subbasin. Organics originated in the headwaters and nursery area, and the residential area was a possible source of microorganisms. The Beaman Pond subbasin was found to be affected by both human and animal sources of contamination. Downstream of the farm, animal contamination was found and supported by measurement of microbial source tracking indicators. The other two sites were affected by human sources, a result of septic systems. Strong correlations were found between several water quality parameters, including temperature and dissolved oxygen, turbidity and particle counts, and fecal coliforms and enterococcus. Based on data usefulness and ease of measurement, it is recommended that temperature, DO, conductivity, pH, dissolved organic carbon, turbidity or particle counts, and fecal coliforms be included in a routine watershed monitoring program.
75

Investigation of the presence and change over time of water quality parameters in selected natural swimming areas in Oregon

Van Ess, Erica 02 May 1997 (has links)
Few studies, and none in Oregon, have examined the presence and change of water quality parameters over time in popular natural swimming areas. This information is necessary to better understand water quality and risk of illness from either fecal contamination or cross-infection from other swimmers. The purpose of this study was to quantitatively measure bacterial and selected physical and chemical parameters, and collect background information for changes to the current state water quality criteria. Five natural swimming areas in Linn, Benton and Polk counties were chosen and sampled biweekly for physical, chemical, and bacterial parameters over a nine week period from June 28 to August 31, 1996. The results showed differences in bacterial levels over the sampling period which often varied by degrees of magnitude between sites. For example, the range in Escherichia coli levels was between 0 and 1000 colonies/100mL sample for two sites on the same sampling day. Similarly, the range in fecal coliform levels was between 5 and 500 colonies/100mL sample. The daily colony counts at each site exceeded the state standards at least 10% of the time for E. coli and 21% of the time for fecal coliform. At the most popular swimming site, Montieth Park. the fecal coliform regulatory levels were exceeded 79% of the time and E. coli levels were exceeded 42% of the time. This may be due to turbidity, high bather load, or a broken sewer line. The 30 day log mean of these values shows consistently elevated fecal coliform problems only at Montieth Park. For the other sites, the log means did not exceed the state and federal regulatory limits for fecal coliform or E. coll. This raises questions about which estimates should be used to assess public health risk. None of the other parameters in this study were correlated with bacterial counts, so it appears that none of these factors is solely responsible for elevated bacterial levels. Further testing should be done at Montieth Park to determine the cause of the elevated fecal coliform levels. Any follow-up studies should test several different indicator organisms in addition to E. coli for comparison and assessment of their relationship to public health risk. / Graduation date: 1997
76

Suspended Sediment Transport Dynamics and Sediment Yields in Relation to Watershed Characteristics, Upper Green River Basin, Kentucky

Otoo, James Nii Aboh 01 April 2010 (has links)
Sediment delivery is a major problem in the Green River, Kentucky, home of 71 of the state’s 103 known mussel species and 151 fish species. The river also provides water for many of its surrounding counties. This research focuses on how suspended sediment loads, grain size, and sediment concentration during runoff events are related to watershed characteristics. The research characterized suspended sediment loads, grain size, and sediment concentration during runoff events and how they were related to watershed characteristics such as hydro-climatic regime, watershed size, geology and soils, topography and landuse conditions and land cover conditions. The study focused on Brush Creek and Pitman Creek watersheds in the Upper Green River Basin. This research can help in the planning and development of effective environmental strategies by screening out mitigation measures that would not be effective for implementation to minimize sediment load and suspended sediment concentration in the Green River, thereby improving the water quality of the river. Water quality was monitored using data sondes positioned at selected sites in the two watersheds. Water samples were collected during turbidity thresholds of 100 NTU and analyzed for suspended sediment concentrations. Regression models between ‘discharge and stage’ and also between ‘average turbidity and suspended sediment concentration’ were formulated and load estimates were made and compared. Four sets of samples were collected, two at Brush Creek on 11 April (Brush Creek’s event 1) and 3 May (Brush Creek’s event 2) and the other two at Pitman Creek on the 12 February (Pitman Creek’s event 1) and 3 March (Pitman Creek’s event 2) all in the year 2008. The suspended sediment samples collected for all four events were well graded but had relatively more silt than clay and sand. This could be due to the fact that more time and energy was needed to break the bonds in clay minerals or particles and also to the fact that more energy was also needed to transport sand compared to silt. Brush Creek watershed’s particles had smaller grain sizes than Pitman Creek watershed’s particles. All four events showed clockwise hysteresis indicating that most of the sediments from both watersheds during the events were derived from the bed and banks of the channel or area adjacent to the channel. The 11 April event (Brush Creek’s event 1) produced an estimated load of 1.1 x 105 kg and a sediment yield of 5.3 x 102 kg/km2. The 3 May event (Brush Creek’s event 2) produced an estimated load of 3.8 x 104 kg and a sediment yield of 1.8 x 102 kg/km2. Brush Creek watershed’s estimated load for the period compared was 4.9 x 105 kg and a sediment yield of 2.3 x 103 kg/km2 (53 kg/km2/day). The 12 February event (Pitman Creek’s event 1) produced an estimated load of 2.9 x 105 kg and a sediment yield of 8.4 x 102 kg/km2. The 3 March event (Pitman Creek’s event 2) produced an estimated load of 5.7 x 105 kg and a sediment yield of 1.6 x 103 kg/km2. Pitman Creek watershed’s estimated load for the period compared was 1.1 x 106 kg and a sediment yield of 3.1 x 103 kg/km2 (71 kg/km2/day). Pitman Creek watershed’s higher number of stream network per unit area, its high elevation and relief, its high percentage of erodible soil per unit area, its lesser area of protection of erodible soil by its vegetation compared to Brush Creek watershed’s are responsible for its higher sediment load and yield.
77

Ecological water quality indices in environmental management

Leung, Wai-shun, Wilson., 梁威信. January 2006 (has links)
published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management
78

Faecal water pollution loads as a function of population growth in Sedibeng and Soshanguve, South Africa.

Teklehaimanot, Giorgis Zekristos. January 2013 (has links)
M. Tech. Water Care. / Aims determining whether inadequate treatment of wastewater and the faecal pollution load of effluents and receiving water bodies in Sedibeng District and Soshanguve peri-urban area of Tshwane Metropolitan Municipality were a function of population growth. To achieve the aim of this study, the following objectives were pursued: Assess the variation in nutrient load and compliance of the physicochemical quality of effluents and receiving water bodies in terms of the South African and World Health Organization standards. Furthermore, the water quality index was also used to assess the overall physicochemical quality status of effluent and receiving water bodies. Assess the compliance of the microbial quality of effluents of the four wastewater treatment plants and their respective receiving water bodies in terms of the South African and World Health Organization limits. Determine the prevalence of Salmonella Typhimurium, Shigella dysenteriae and Vibrio cholerae in the targeted wastewater treatment works effluent and their respective receiving water bodies. Determine the possible public health risks of Escherichia coli, Salmonella Typhimurium, Shigella dysenteriae and Vibrio cholerae infections that could be acquired due to ingestion of or exposure to untreated water from the targeted receiving water bodies. Capture information regarding population growth and wastewater treatment plants in Sedibeng District and Soshanguve peri-urban area of Tshwane Metropolitan Municipality and determine whether under performance of the targeted wastewater treatment works could be attributed to population growth.
79

Environmental management of mariculture in Hong Kong

Choi, King-wah, David., 蔡景華. January 2002 (has links)
published_or_final_version / abstract / toc / Civil Engineering / Doctoral / Doctor of Philosophy
80

Assessing the Source of Fecal Contamination in Streams on Kaua'i Based on Concentration and Genotypes of FRNA Bacteriophages

Vithanage, Gayatri 08 1900 (has links)
Extensive data from O'ahu indicate that all streams on this island consistently exceed the USEPA standards (200 fecal coliform/100 ml, 33 enterococci/100 ml) for water quality. Soil was determined to be the source of the elevated counts of these bacteria. In tropical areas, as Hawai'i, these bacteria are able to survive and multiply in the soil. Thus, these bacteria can end up in nearby streams after heavy rains or due to erosion. As a result, the USEPA recommended indicator bacteria (fecal coliform, enterococci) cannot be used to reliably determine when waters in tropical areas are fecally contaminated. Several alternative indicators have been proposed for such areas such as C. perfringens and FRNA coliphages. Extensive monitoring data does not exist for the other islands of Hawai'i. Kaua'i differs from O'ahu in that it is older, wetter and contains an abundance of cesspools. The Nawiliwili Watershed, on the island of Kaua'i, was chosen for this study. Sampling was conducted over a period of one year, and all samples were assayed for the traditional USEPA indicators (fecal, coliform, enterococci) as well as two alternative indicators (C. perfringens, FRNA coliphages). Of the 14 sites sampled, 12 contained levels of fecal coliform and enterococci that exceeded the USEPA standards (200 fecal coliform/100 ml and 33 enterococci/100 ml. This is similar to what has been documented in O'ahu streams. Based on the concentrations of these indicator bacteria, the USEPA would deem these sites as sewage contaminated. However, monitoring of these same sites for C. perfringens indicated that there was no sewage contamination (geometric mean values fell below the proposed standard of 50 CFU/100 ml). FRNA coliphage data indicate that cesspools may be leaching into nearby streams. Two streams (Nawiliwili, Papakōlea) had geometric mean levels greater than the 50 PFU/100 ml (based on O'ahu streams). Other streams in the watershed may be sporadically contaminated by cesspool because elevated FRNA coliphage levels were detected on occasion. Genotyping these FRNA coliphage isolates furthered supported the theory that cesspools were contaminating these sites because 98% of the FRNA isolates were typed as human while only 2% were typed as of animal origin. Current USEPA standards (fecal coliform, enterococci) are not reliable indicators of sewage pollution in tropical areas, thus, alternative indicators such as C. perfringens and FRNA coliphages may prove to be better indicators in these areas.

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