A contaminação de água subterrânea por coliformes fecais em propriedades rurais está diretamente relacionada com o saneamento básico rural oferecido, assim como as doenças de veiculação hídrica contraídas por essas populações. Esta pesquisa analisa a contaminação da água de consumo humano proveniente de poços, considerando os índices de potabilidade descritos na Portaria do Ministério da Saúde nº 2.914 e na Resolução CONAMA nº 398. Tem-se como estudo de caso uma área rural no município de Caxias do Sul, estado do Rio Grande do Sul, inserida na da bacia hidrográfica do arroio Marrecas. Foram realizados estudos por meio de informações contidas em relatórios técnicos, normatizações federais e bibliografias especializadas, para contextualização, conceituação e teorização de saneamento básico rural, qualidade e contaminação da água subterrânea, doenças de veiculação hídrica e poços. Mediante o uso do estimador de densidade Kernel, levantou-se o número de residências a serem entrevistadas. Durante o processo de entrevistas, averiguou-se a existência de saneamento básico rural nas propriedades, porém a maioria dos poços não estavam protegidos do acesso e/ou de serem contaminados por animais. Isto justificou a necessidade de realização de análise da qualidade da água subterrânea consumida por meio de poços particulares. Os resultados das entrevistas diagnosticaram uma população ambientalmente consciente sobre a preservação do meio e sobre a qualidade da água consumida. Contudo, os resultados das análises indicaram que a água ingerida estava contaminada por coliformes, assim como também houve relatos de doenças de veiculação hídrica, confirmando o saneamento deficiente em algumas propriedades rurais. / The contamination of groundwater by fecal coliforms in rural properties is directly related to the available basic rural sanitation, as well as to water-borne diseases contracted by these populations. This research analyzes the contamination of potable well water, applying the potability indicators described in the Ministry of Health Directive Nº. 2914 and the Brazilian Environment Council (CONAMA) Resolution No. 398. A rural area in the city of Caxias do Sul, Rio Grande do Sul, located within the hydrographic basin of the Marrecas stream, was used as the case study. Studies were conducted by using information contained in technical reports, federal guidelines, and specialized bibliographies, for the context, concepts and of basic rural sanitation, quality and contamination of groundwater, waterborne diseases and wells. The number of households to be interviewed was determined by using the Kernel density estimator. During the interview process, the existence of basic rural sanitation was verified in the properties, however, a majority of the wells were not protected from the access and/or from being contaminated by animals. This justified the need for conducting the analysis of the quality of groundwater consumed by way of individual wells. The interviews resulted in the diagnostic of an environmentally conscious population, aware of preserving the environment and of the quality of water consumed. However, the results of the analyses indicated that the drinking water was contaminated by coliforms, and there were also reports of waterborne diseases, confirming the poor sanitation in some rural properties.

Water quality is concerning as many still lack access to safe drinking water. Alternate sources such as rivers (FC up to 1600 CFUs/100 mL) and rainwater are often polluted. Rainwater tanks require maintenance to improve water quality, but could be used for non-potable purposes or irrigation. Grahamstown infrastructural failures initiate deviations from DWAF 1996 domestic water guidelines for microorganisms within the distribution system. Frequent testing can decrease risks of waterborne diseases. Limitations to this are inaccessibility of rural areas, distances from testing centres and costs. The low cost H2S strip test able to be used onsite by communities, may aid in risk assessment. H2S strip test results are not affected by sulphate (14 to 4240 mg/L) or nitrite (up to 47 mg/L). Transportation of the H2S strip tests between 10 and 32°C does not modify results significantly. Similarly to other studies: Klebsiella spp.; Enterobacter spp. and Serratia spp. were isolated from H2S strip tests. The mH2S strip test corresponds best with HPC in treated water, while in untreated river water it has approximately 90% correspondence with FCs, while survival of FC causes discrepancies with the H2S test after 22 days. A faecal coliform inactivation rate of 0.1 CFUs/ day, may be longer than many pathogens. Faecal source tracking, not currently practised in South Africa, could aid health risk assessments for disaster management, which would improve the NMMP programme. Bacterial survival times could propose the time period for which water is unsafe. Bifidobacteria and Rhodococcus are proposed to help identify the faecal pollution source. But enumeration of Rhodococcus is too lengthy (21 days). The tracking ratio of bifidobacteria (between 0.1 to 6.25) is not source definitive. The bifidobacteria survival rate, could indicator the time since faecal pollution. The bifidobacteria average survival rate is 2.3 CFUs per day for both groups. The culturability and selectivity of agar is still poor, with total bifidobacteria less selectively culturable. Enterococci overgrowth of TB was decreased by Beerens media. SUB is still useful to identify potential human faecal inputs. A single tracking method is thus not suitable alone, but requires a combination of techniques.

Ph.D. / Members of Cichlidogyrus are monogenean ectoparasites occurring on the gill filaments of mainly cichlid fishes. An overview of the taxonomic background of the genus and motivation for the study is provided. In this study, existing information on their distribution is organised in a comprehensive table which includes 85 species, their taxonomic authors, hosts and localities from which they have been recorded. Representatives of this genus occur mainly in Africa, but have been found on cichlids as far as Mexico. Host specificity of members of the group is discussed. During the present investigation specimens of the genus Cichlidogyrus were found parasitising Pseudocrenilabrus philander philander, in the Padda Dam in Johannesburg, Gauteng, South Africa. Specimens were examined and identified as Cichlidogyrus philander, previously described from the same host, from Lake Kariba, in Zimbabwe. The morphology was studied utilizing light – and scanning electron microscopy. Specimens were stained with Horen‟s trichrome and photographed. Furthermore 100 whole mounted specimens, which were fixed and mounted in glycerine-ammonium-picrate, were measured. Larval specimens, and mature individuals with eggs in situ, were examined. The investigation of the ecology entailed monthly surveys during which a total of 245 fish specimens were collected with the aid of hand nets, over a period of 14 months (from March 2006 to June 2007). The fish were transported to the laboratory and killed by severing the spinal cord. Gills of specimens of P. p. philander (111), Gambusia affinis (105), Tilapia sparmanii (28) and one (1) 2 specimen of Cyprinus carpio were inspected, for the presence of monogeneans, with the aid of a dissection microscope. Only members of P. p. philander were parasitised by C. philander, indicating strict host specificity. The number of specimens varied from 0 to 184 per fish. The highest mean intensity of 91.6 occurred in the winter month of June 2007, although no significant correlation between season and the occurrence of this parasite was recorded. The prevalence was 100 % for ten of the fifteen surveys and no preference for host sex was recorded. The intensity of the infection correlates positively to the total length of the host, i.e. larger hosts harbour more worms. A positive correlation between condition factor and the total number of worms was found, indicating that more parasites are found on fish with a normal condition factor. No significant difference occurred between the numbers of parasites collected from gill arches on the left or right sides of fish. Statistical analysis of data showed that parasites disperse across the four gill arches with a higher proportion of parasites on the third and second gill arch. The highest proportion of the collected parasites occurred on the dorsal regions and on the distal ends of the gill filaments. Water quality variables do not significantly correlate to the prevalence, abundance or mean intensity of this parasite. This is the first ecological study conducted on specimens of C. philander, worldwide.

MESHWR / Department of Hydrology and Water Resources / Water borne diseases due to inadequate and unsafe drinking water is a global challenge that has led to a significant number of deaths and illnesses reported annually. These diseases are prevalent in less-developed countries, especially in rural areas where there is shortage of basic infrastructure and inadequate funds for piped water systems in individual households. Community members are forced to resort to collecting water from communal water points and later storing the water in containers for daily use. Recontamination of microbiologically safe drinking water during and after collection from the water source has been recognised as a problem; hence treating water at household level is one way to provide potable water for affected communities. The microbiological quality of household water may be improved by using point-of-use treatment technologies such as chemical disinfection, solar disinfection and ceramic water filters. Some of these technologies are expensive, less effective and difficult to implement in rural communities. This research thus focused on ceramic water filters and finding an appropriate method for silver application so as to produce filters that are effective in both the provision of clean drinking water and the release of silver levels that are safe for human consumption. An assessment of the efficiency of ceramic water filters made with silver nitrate as point-of -use water treatment device in Dertig Village, North West Province, South Africa was carried out. During production of filters made with silver nitrate, the filters undergo firing in an electric kiln and ionic silver is reduced to metallic nanopatches dispersed throughout the porous ceramic media. Both filters made with silver nitrate and conventional silver nanoparticles impregnated ceramic water filters were manufactured at the PureMadi Dertig Ceramic Filter Facility, South Africa. Resulting filters were evaluated and quantified for total coliform and E. coli removal as well as silver concentration in the effluent. Ceramic water filters made with silver nitrate had a high removal efficiency for total coliforms (94.7%) and E. coli (99.3%). A comparison of the performance of filters made with silver nitrate and silver nanoparticles in the provision of potable water was carried out and results showed that the different filters had similar levels of total coliform and E. coli removal, although the silver nitrate filters produced the highest average removal of 97.23% while silver nanoparticles filters produced the lowest average removal of 85.43%. Reasonable silver levels were obtained in effluent from all filters. Average effluent silver levels were 0.07±0.04mg/L, 0.6±1.10 mg/L and 0.8±1.0mg/L for 1 g, 2 g and silver nanoparticle filters, respectively (below the EPA and WHO standard of 100 mg/L). Because silver nitrate filters resulted in the lowest effluent silver concentrations, this could potentially increase the effective life span of the filter. A cost analysis of the process proved that it was cheaper to produce ceramic water filters using silver nitrate as the chemical can be purchased locally and also eliminates labour related costs. Thus, filters made using silver nitrate could potentially improve performance, reduce production costs, and increase safety of production for workers. The results obtained from this study will be applied to improve the ceramic filtration technology as point-of-use water treatment device in an effort to reduce health problems associated with microbial contamination of water stored at household level. / NRF

No description available.

The movement of the exotic and destructive plant pathogen Phytophthora ramorum into unquarantined areas via the plant nursery trade provides a potential outlet for transmission into eastern United States forests. A two-year survey of Phytophthora species in a forest adjacent to an ornamental plant nursery in Mississippi isolated P. ramorum 20 times from water and once from vegetation, with an additional detection of 14 Phytophthora species and one provisional species. Isolates were recovered from soil, water, and vegetation using baiting and filtering techniques, and verified by their DNA through Polymerase Chain Reaction (PCR) followed by genomic sequencing. This study confirms the ability of P. ramorum to sustain itself in Mississippi, although disease progression appears to be inhibited by the relatively small window of favorable environmental conditions.

The Mississippi Alluvial Plain, a robust agricultural region in the South-Central United States, provides commodities across the United States and around the world. Water for irrigation, which is necessary due to irregular rainfall patterns during the growing season, is withdrawn largely from the Mississippi River Valley Alluvial aquifer, one of the most intensely used aquifers in the United States. The groundwater-dependent region has observed recent declines in groundwater and streamflow levels, raising concerns about the availability and use of fresh-water resources. Declining water levels have prompted investigation into the current understanding of groundwater and surface-water interaction. Previous research does not adequately quantify the unobservable exchange of water between surface-water bodies and the underlying aquifer. This research was designed to advance the current understanding of the interaction between groundwater and surface water through the quantification of spatial and temporal trends in streamflow and groundwater level changes and the use of high-resolution spatial estimates of streambed hydraulic conductivity. Changes in streamflow and groundwater levels were quantified with the use of hydrograph-separation techniques and trend analyses. High-resolution estimates of streambed hydraulic conductivity were found through the correlation of waterborne continuous resistivity profiling data to hydraulic conductivity and streambed hydraulic conductivity estimates were incorporated into the existing Mississippi Embayment Regional Aquifer Study (MERAS) groundwaterlow model. Site-specific empirical relationships between resistivity and hydraulic conductivity were developed with near-stream borehole geophysical logs to improve model estimates of streambed hydraulic conductivity. Results of the quantification of changes in streamflow and groundwater levels suggested agricultural groundwater withdrawals for irrigation to be the primary source of groundwater-level declines. Results from the incorporation of high-resolution estimates of streambed hydraulic conductivity showed that the existing groundwaterlow model is sensitive to changes in streambed hydraulic conductivity, which may impact model accuracy. The incorporation of streambed hydraulic conductivity estimates derived from site-specific empirical relationships impacted MERAS model water-budget estimates. Information gained from this research will be used to improve the existing groundwaterlow model, which acts as a decision-support tool for water-resource managers at state and local levels to make informed water-use decisions for the conservation of fresh-water resources for sustainable agricultural irrigation practices.

No description available.

No description available.

No description available.