Ground water has traditionally been considered safe for human consumption without treatment. However, it is an increasingly significant cause of human disease. Although ground water accounts for only approximately 20% of the nation's water supply, over 50% of the waterborne disease outbreaks in the United States are due to the consumption of contaminated ground water. It has been estimated that 65% of the cases of illness in these outbreaks are caused by enteric viruses. Little, however, is known about the persistence of viruses in ground water. The purpose of this study was to try to determine the chemical, physical, and biological factors influencing virus survival in ground water. This information will be helpful in developing criteria for determining safe distances between drinking water wells and sources of potential contamination such as septic tanks and waste application sites. Ground water samples were obtained from eleven sites throughout the United States. In addition, twenty samples were collected from the Tucson basin. The water temperature was measured at the time of collection. Several physical and chemical characteristics (including pH, nitrates, turbidity, and hardness) were determined for each sample. Separate polypropylene tubes containing 50 ml of water were inoculated with each of three viruses: poliovirus-1, echovirus-1 and MS-2 coliphage. Duplicate tubes containing water which had been filtered to remove the indigenous bacteria were also inoculated with viruses. The tubes were incubated at the in situ ground water temperature; selected samples were incubated at two additional temperatures. One-ml subsamples were withdrawn at predetermined intervals over a 30-day period and assayed to determine the number of microorganisms remaining. Multiple regression analysis revealed that temperature was the only water characteristic significantly correlated with the decay rates of all three viruses. Bacteria did not have a consistent effect on the decay rate of the viruses. In addition, no significant differences were found among the decay rates of the three viruses, suggesting that MS-2 coliphage may be able to be used as a model of animal virus behavior in the environment.

Thesis (Ph. D.)--Oregon State University, 2007. / Printout. Includes bibliographical references (leaves 135-150). Also available on the World Wide Web.

Thesis (Ph.D.). / Written for the Dept. of Natural Resource Sciences, Macdonald College of McGill University. Title from title page of PDF (viewed 2008/07/24). Includes bibliographical references.

Thesis (M.S.)--State University of New York at Binghamton, Department of Biological Sciences, 2008. / Includes bibliographical references.

Thesis (M.S.)--Missouri State University, 2008. / "May 2008." Includes bibliographical references (leaves 81-83). Also available online.

Thesis (MSc)--University of Stellenbosch, 2003. / ENGLISH ABSTRACT: Biofouling of water systems is a problem extensively experienced in industry. Although this subject is the focus of many studies, the ability of microorganisms to survive exposure to biocides is still poorly understood. This study aimed to assess the biocidal effect of ozone on planktonic cells and biofilm communities, to evaluate different ozone generation techniques, and to follow population shifts within the biofilm community. Specific objectives included determining the effect of different ozone concentrations, the effect of different exposure times, and an assessment of microbial responses after exposure to sub-lethal ozone concentrations. Typically, 300 ml of an ovemight bacterial culture was exposed to ozone that was generated by anodic oxidation (0.3% wt or 18- 20% wt, respectively) or silent electric discharge (3.5% wt 03). The ozone was purged into the culture for 5-, 7-, 10- and 15 min., respectively. Enumeration of cells following ~10 min. exposure to 18-20% wt ozone showed a significant reduction in viable cell numbers. In contrast, when exposed to the two lower 03 concentrations, there was little change in the viable cell numbers even after prolonged exposure (30- and 60 min.). To evaluate biofilms, ozone was bubbled into the irrigation that was pumped through replicate flow cell channels. Response to ozone exposure was evaluated after staining the biofilms with the Baclight Viability probe, observation with fluorescence microscopy, and image analysis. The higher ozone concentration (18-20% wt 03) more effectively disrupted the biofilm structure of denser biofilms than the lower concentration, especially after 90 min. exposure. When compared to the controls, the 90 min. exposure resulted in a notable reduction in viable cells from 69% to 38% and a corresponding increase in nonviable cells from 29% to 62%. The lower concentration ozone (3.5% wt 03) was effective against the less dense, thinner biofilms evaluated, but not effective against the thicker biofilm. An analysis of the differences between continuous culture biofilms and batch culture biofilms showed that the biofilms in the batch system were less rigid. To evaluate microbial response to biocides, techniques such as Biolog whole-community metabolic profiles and terminal restriction fragment length polymorphisms (T-RFLP) were used. Biolog analysis of planktonic cells revealed changes following exposure to sub-lethal biocide concentrations, however carbon utilisation profiles resembled that of the controls after 24-48 hours. For biofilm communities, no carbon utilization differences could be detected under these conditions. There was, however differences in T-RFLP patterns between treated and untreated biofilm communities. / AFRIKAANSE OPSOMMING: Biobevuiling van watersisteme is 'n probleem wat algemeen in industriëe ervaar word. Alhoewel hierdie onderwerp die fokus van vele studies is, word die vermoëns van mikroorganismes om blootstelling aan biosiede te weerstaan steeds swak verstaan. Die doel van hierdie studie was om die biosidiese effek van osoon op planktoniese selle en biofilm gemeenskappe waar te neem, om die verskillende osoon generasie tegnieke te evalueer, asook om verskuiwings in die samestelling van die biofilm gemeenskap waar te neem. Spesifieke doelwitte sluit in die bepaling van die effek van verskillende osoon konsentrasies, die blootstellingtye, en 'n waarneming van mikrobiese reaksies na blootstelling aan sub-dodings osoon konsentrasies. Drie honderd ml van 'n oornag bakteriese kultuur was aan osoon, wat deur anodiese oksidasie (0.3% wt of 18% - 20% wt) of geluidlose elektriese ontlading (3.5% wt), gegenereer is, blootgestel. Tye van blootstelling was 5-, 7-, 10-, of 15 min., onderskeidelik. Bepaling van selgetalle na :2:10 min. blootstelling aan 18 - 20% wt osoon, het 'n betekenisvolle verlaging in die getal lewensvatbare mikrobeselle getoon. In teenstelling hiermee, het blootstelling aan twee laer osoon konsentrasies min verskil in die lewensvatbare selgetalle, selfs na verlengde blootstellingstye (30- en 60 min.), getoon. Om biofilms te evalueer is osoon in die medium geborrel wat deur replikaat vloeisel kanale gepomp is. Na osoon blootstelling, was die vloeisel onderwerp aan beeld analise deur gebruik te maak van die Baclight lewensvatbare peiler en fluoressensie mikroskopie. Die hoër osoon konsentrasie (18 - 20% wt 03) het die struktuur van dikker biofilms meer effektiefuiteengeskeur as die laer konsentrasie, veral na 90 min. blootstelling. In vergelyking met die onderskeie kontroles, het die getalle van lewensvatbare selle na 90 min. blootstelling drasties verlaag vanaf 69% tot 38% en 'n ooreenstemmende toename in die nie-lewensvatbare selgetalle vanaf 29% tot 62%. Die laer osoon konsentrasie (3.5% wt 03) was meer effektief teenoor die minder digte en dunner biofilms wat ge-evalueer was, maar nie so effektief teenoor die dikker biofilms nie. 'n Analise van die verskille tussen kontinue-kultuur biofilms en lotkultuur biofilms het getoon dat die lot-kultuur biofilms minder rigied is. Vir die evaluering van mikrobiese reaksies na biosied blootstelling, is tegnieke soos Biolog gemeenskap metaboliese profiele en eind-restriksie-fragment-lengte polimorfisme (TRFLP) gebruik. Biolog analise van planktoniese selle het verskille getoon na blootstelling aan sub-dodelike biosied konsentrasies. Koolstof benutting het wel na 24 - 48 ure met dit van die kontrole ooreengestem. Vir biofilm gemeenskappe was daar geen noemenswaardige verskille in koolstof benutting nie. Daar was wel verskille in T-RFLP patrone tussen die onbehandelde en biosied-behandelde biofilm gemeenskappe.

Enteric viruses are viruses which replicate in the intestinal tract of man and animals. One mode of transmission for enteric viruses is the fecal-oral route. Drinking water which has been contaminated with sewage or sewage effluent has been implicated as a means for the spread of enteric viruses. Monitoring water for virus contamination requires two steps: 1) the collection and the concentration of the water sample and 2) the isolation and identification of the virus present. Current methods for the detection of enteric viruses in water requires the use of animal cell culture. This technique has several drawbacks, such as: 1) long incubation periods, up to two and three weeks, before some enteric viruses are detected, 2) not all viruses can be detected in one cell line, and 3) not all viruses have been grown in cell culture. More rapid techniques, such as fluorescent antibody or radioimmunoassay do not have the needed sensitivity to detect the low levels of virus found in contaminated water. These techniques also require the production of an antibody for each different virus type. An alternative technique for the detection of viruses in water was sought. Recent advances in recombinant DNA technology now makes it possible to detect viruses without the use of cell culture or antibodies. Gene probes that hybridize to the RNA of poliovirus and hepatitis A virus were tested for their ability to detect different enteric viruses. The probes were labeled with ³²P dCTP and ³²P dATP to a specific activity greater then 1.0 x 10⁹ cpm/ug DNA. Gene Screen Plus (NEN) was chosen as the hybridization membrane since it was more sensitive to virus detection than the other membranes tested. A dot-blot apparatus (Bio Rad) was used to apply the samples. Results were visualized by autoradiography for thirty-six hours at -70° C. One infectious unit of poliovirus and hepatitis A virus was detected using labeled cDNA probes. Upon comparison, the dot blot assay was as sensitive as tissue culture for the detection of poliovirus in beef extract, secondary effluent, and tapwater. Environmental samples, such as secondary effluent, reclaimed wastewater and unchlorinated drinking water were also assayed for poliovirus and hepatitis A virus with the use of gene probes. The results presented here offer an alternative method for screening water samples for the presence of enteric viruses.

Fens are increasingly recognised as important habitats in terms of biodiversity, and this has been formalised in recent legislation (EC Habitats Directive, 92/43/EEC). The influence of groundwater and surface water inputs on the fen habitat increases its vulnerability to water pollution, particularly from nutrients. Despite the conservation importance and potential vulnerability of the habitat, fens have not been widely studied in Scotland, in terms of extent, location, sensitivity to increased nutrient inputs, or in comparison to similar European sites. This study found that fens were widespread throughout mainland Scotland, and that basin fens were the most commonly occurring fen type, representing 43% of the 355 sites assessed. A survey of 18 basin fens found that 72% were potentially vulnerable to elevated nutrient inputs, being surrounded by improved/modified land. Despite this, only four sites showed greater nutrient concentrations in sub-surface water samples or water inputs. There was, however, a significant amount of variation in hydrochemistry between the sites. Detailed studies further assessed spatial and temporal variations in hydrochemistry, and associated hydrologic regimes on two similar basin fens, one in an agricultural catchment, the other surrounded by unimproved grassland. Spatial patterning of vegetation was associated with both base-richness and nutrient concentrations of subsurface water, and the frequency of water inundation. General relationships between the six fen vegetation types and the observed hydrological and hydrochemical variation were presented.

Thesis (M.S.)--University of Nevada, Reno, 2005. / "December 2005." Includes bibliographical references (leaves 69-72). Online version available on the World Wide Web.

Thesis (M.Sc.)--Memorial University of Newfoundland, 2001. / Bibliography: leaves 117-125.