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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.
491

Transformation of Nitrogen in Highway Runoff Management Systems

Tolbert, Robert D. 01 January 1984 (has links) (PDF)
The operation and maintenance of highways contributes a variety of pollutants to surface and subsurface waters. Solids, heavy metals, nutrients, oil and grease, pesticides and bacteria can all be associated with highway runoff. Although the full extent of the effect of all of these runoff constituents upon the quality of surrounding waters is not well defined, this study will mainly concentrate on nutrient contaminants (essentially nitrogen). The last decade has seen increasing efforts in research and development to abate contaminant discharges from highway runoff using a number of treatment facilities such as retention/detention basins, swales and wetland systems. An evaluation of the effectiveness of these systems in removing nitrogen by physical, chemical and biological uptake is the aim of this research endeavor. This information could prove invaluable in an overall assessment of the effectiveness of highway runoff treatment systems.
492

Pollution survey of Claytor Lake

Dodge, Peter Cook, Eye, John David January 1949 (has links)
The conclusions of this survey should be considered with the fact in mind that it was in the nature of a preliminary or reconnaisance rather than a final survey. While the authors feel that the conclusions drawn are justified by their test results it should be realized that the data is not comprehensive or complete enough to draw any final conclusions regarding the overall sanitary condition of the lake. Considering the test results, the following conclusions and recommendations are presented: 1. There is evidence of pollution throughout the portions of the lake tested, during the extent of the sampling season. 2. The pollution at Sections 1, 2, and 3 showed a tendency of being localized in relatively narrow well defined channels, while that at Section 4 seemed to be dispersed throughout the cross section. 3. The water in the vicinity of the V.P.I. property and the upstream part of the state park property would, in general, meet the various bacteriological requirements of health departments for bathing areas. 4. The water just below the proposed bathing area at the downstream part of the state park showed evidence of pollution in amounts which might make the use of this area questionable unless careful control is maintained by frequent bacteriological tests. 5. There was no evidence of a trend or fluctuation in pollution during the period of study. 6. In general, there was no correlation between the results of the bacteriological tests and the chemical and physical results. / M.S.
493

Physio-morphological effects of abrupt thermal stress on diatoms

Lanza, Guy R. 20 May 2010 (has links)
Introduction: Increased temperature as a stress factor in aquatic environments has recently received much attention. Human population growth accompanied by expanded demands for electrical energy has resulted in increased construction of power generating facilities. Conventional fossil fuel power plants are being built to produce many times the electricity of those built in previous years. Nuclear power plants, not economically feasible in small sizes, are being constructed to generate even more electrical energy per unit than the new conventional units. Nuclear power facilities produce heat less efficiently and, thus, require approximately fifty percent more cooling per BTU than usual methods (Kolflat, 1968). Increased exposure of populations and communities of aquatic organisms to thermal pollution can thus be anticipated when natural water systems are utilized as a cooling source. The majority of research effort relative to the effects of heated waste waters on aquatic systems has been directed towards macro- as opposed to micro-organisms. While the use of microorganisms in general pollution monitoring is not a nevi concept; for examples see Kolkwitz and Marsson (1908); Butcher (1947); Fjerdingstad (1962), most of the existing effort has been in the area of correlation of species to various polluted situations. The major disadvantages of such approaches as well as the use of populations and communities of microorganisms in pollution monitoring are discussed in Cairns and Lanza (1971) and Cairns, etc. (submitted)... <i>Vita removed Nov. 30, 2011. GMc</i> / Ph. D.
494

Determining Sources of Fecal Pollution in Washington D.C. Waterways

Porter, Kimberly Rae 15 December 2003 (has links)
Antibiotic resistance analysis (ARA) of Enterococci was used to determine sources of fecal contamination in three District of Columbia waterways: Rock Creek, the Anacostia River, and the Potomac River. These three waterways were identified as exceeding water quality standards set for fecal coliform levels and were designated by the District of Columbia to the Environmental Protection Agency's 303 (d) impaired waters list. A library profile of 1,806 enterococcus isolates from known sources was built based on antibiotic resistance patterns from thirty concentrations of nine antibiotics. These sources included human, cattle, chicken, horse, goat, sheep, deer, raccoon, muskrat, goose, seagull, coyote, duck, wild turkey, dog, and cat. Antibiotic profiles were characterized for 24 unknown enterococci isolates on each of 198 samples (38 samples from the Potomac River, 79 samples from the Anacostia River, and 81 samples from Rock Creek) collected periodically from July 2002 through April 2003. Two major storm events were also sampled during this period. These isolate profiles were compared to the known source library using logistic regression. Three dominant sources of fecal pollution were detected in the Potomac River: livestock (30%), human (29%), and wildlife (22%). Three dominant signatures were also detected in Rock Creek: horse (26%), human (26%), and wildlife (24%). Human was the only dominant source detected in the Anacostia River, averaging 43% over the sampling period. The results of this study indicate that human is a substantial contributor to the fecal contamination problems, especially in the Anacostia River, but there are significant agricultural and wildlife contributions as well. Significant and predictable seasonal variations were also detected, indicating the influence of precipitation on source distributions. The results of this study will aid the Metropolitan Washington D.C. Council of Governments in making important management decisions to help improve the water quality in and around the Washington D.C. area. Expanding the limits of ARA was also an integral part of this research. Three new and even controversial analytical techniques were run on the data collected from this project in an attempt to improve confidence and provide direction to the results of this study. The first was a comparison of the more commonly used statistical analysis model discriminate analysis (DA) with logistic regression (LR). No significant difference was found between the output of the two models for the known source libraries, therefore no suggestion could be made in favor of one model over the other. Another analytical test of the data was the introduction of a standard requiring isolates to meet a minimum of 80% similarity to the known source profiles where it was classified. With the 80% cutoff, between 41% and 44% of the isolates could not be classified to any source and were placed in an unknown category. Based on the remaining isolates, source distributions were recalculated and were not statistically different than those calculated with no restriction for isolate similarity for matching. The last major test of the data was the analysis of the library for representativeness via pulled sample cross validation and the exclusion of all duplicate patterns from the known source library. These analyses did not confirm the representativeness of the databases, but results were further analyzed based on the implications these analyses have on library based methods. / Master of Science
495

The sewage lagoon: its social, economic, and planning implications

Cherches, Charles William January 1961 (has links)
The basic objectives of this study were to determine: (1) the extent of water pollution contributed by our communities in the form of municipal and industrial wastes, (2) an investigation of the extent of use, performance characteristics, and costs or the sewage lagoon, (3) the planning aspects of the sewage lagoon, (4) the extent of anti-pollution law enforcement, and (5) the existing financial aid available to communities tor the construction of' sewage lagoons. The findings of this study indicate that: 1. The extensive contribution to the water pollution problem by municipalities and industry is serious. The projection of future water use based upon present standards of use and recovery indicates a very serious water problem in the near future. A need exists for an inexpensive method or sewage treatment. 2. Sewage lagoons are relatively new but are widely used. They have proved to be relatively inexpensive and are achieving a high standard of purification. 3. Possible secondary benefits resulting from the use of sewage lagoons may prove to be of substantial value to municipalities in terms of efficient land use and the preservation of open land for alternate future uses. 4. The enforcement of the existing anti-pollution laws have been ineffectively enforced; however, new emphasis is being placed upon legal proceedings I rather than the voluntary compliance that has been practiced in the past. 5. With proper planning, a community can conceivably use several governmental programs for financial assistance both in grants-in-aid and long term loans for the construction or a sewage lagoon. / Master of Science
496

The effect of salinity on nutrient release from riverine and tributary estuarine sediments to the Chesapeake Bay under oxidizing and reducing conditions

Lee, Wen-Hsiung January 1988 (has links)
The primary objective of this study was to determine the salinity effect on nutrient release and the denitrification rate in a sediment-water system. To accomplish this objective, bench-scale microcosm studies of York River sediments and Occoquan Reservoir sediments were conducted. Seawater and freshwater were mixed in various ratios to simulate seasonal, salinity-varying environments in the Chesapeake Bay and its tributary estuaries. Experiments were conducted under aerobic, anaerobic, and anoxic conditions. The results showed that high salinity can cause flocculation of particles and result in lower concentration of phosphate under aerobic conditions, but the flocculation effect was not obvious under anaerobic conditions. The release of ammonia was governed by the salinity; the increasing salinity accelerated the release of ammonia by ion exchange. The denitrification rate under anoxic conditions in the system was not influenced by the salinity. / Master of Science
497

Energy levels and anaerobic endproducts in the brains of two species of teleost fish at death in anoxic water

DiAngelo, Constance Rose 14 November 2012 (has links)
The brain of fish, as in other vertebrates, is responsible for many functions basic to life and is also thought to be an anoxia-sensitive tissue. Therefore, during anoxia, the maintenance of energy within the brain is of paramount importance to the survival of the animal. Studies concerning energy levels and storage and the use of anaerobic metabolism in fish brains following exposure to anoxia are lacking. Rainbow trout (<u>Salmo gairdneri</u>) and brown bullhead catfish (<u>Ictalurus nebulosus</u>) occupy ecologically distinct habitats. Their tolerance of anoxia is different; trout survived l2 minutes while bullhead survived 62 minutes in anoxic water. Brains from control and anoxiaâ exposed trout and bullheads were analyzed using enzymatic assays and high pressure liquid chromatography (HPLC). Control bullhead brains had higher concentrations of glycogen, ATP, CrP, and glucose than control trout. With anoxia, bullheads showed a significant decrease in ATP, CrP, and glycogen with no change noted for glucose, ketone bodies (betaâ hydroxybutyrate and acetoacetate), or alternative anaerobic endproducts (succinate, alanine, propionate, isobutyrate, isovalerate, and ethanol). Lactic acid increased two-fold with anoxia. The bullhead was able to generate ATP by depleting its CrP stores and through classical anaerobic glycolysis. Death was most likely due to an inability to maintain ATP levels. Catfish may survive anoxia longer than trout in part due to greater fuel stores. Rainbow trout brain stored approximately one sixth the amount of glycogen as bullheads. With anoxia, these stores were depleted but there was no significant decrease in ATP, CrP, or glucose; the alternative endproducts also did not change. There was a l00% increase in lactic acid, suggesting that anaerobic glycolysis helped maintain ATP levels. Death may be due to factors other than ATP depletion such as lactic acid injury and increased intracellular free calcium. / Master of Science
498

Aquatic microbial community responses to stress: comparison of nontaxonomic and taxonomic indices

Toczydlowski, David G. 14 November 2012 (has links)
Three nontaxonomic indices; ATP/Chlorophyll <u>a</u>(ATP/Chla), ATP/ADP, and Chlorophyll <u>a</u>/Pheopigment (Chla/Pheo) were compared to the taxonomic measures of species diversity (d) and species richness as indicators of stress in aquatic environments. Field and laboratory microcosm responses of indigenous microbial communities exposed to municipal sewage treatment plant (STP) effluent were monitored. The STP effluent produced increased adenylate concentrations, ATP/ADP and ATP/Chla ratios, and decreased Chla, Chla/Pheo, d, and species richness relative to upstream reference communities. Nontaxonomic responses were consistent in four separate field tests. Significant differences in responses were discernible in 3 d when communities were transferred from reference to polluted sites. Chla/Pheo decreased more rapidly than other measurements. The predictive capability of laboratory flow through microcosm tests was examined by simultaneously transferring communities from upstream reference sites to downstream field sites and to various dilutions of field effluent in the laboratory. / Master of Science
499

Contamination of a soft-water stream ecosystem in southwest Virginia by highway-generated heavy metals

VanHassel, John Herbert January 1979 (has links)
Study of two sections of a stream associated with highways of different traffic densities and a third section used as a reference area demonstrated that concentrations of lead, nickel, cadmium, and zinc in sediments, benthic macroinvertebrates, and fish were highly correlated to the amount of traffic associated with the respective sampling site. Highest sediment concentrations of lead, nickel, and zinc occurred in spring, most likely due to accumulation and subsequent runoff in snow. Accumulation of these metals in invertebrates and fish is probably a more· time-dependent process. Concentrations in these organisms were related to physiological and ecological factors as well as the relative availability of each metal at each study site. The major physiological factor influencing accumulation of heavy metals in stream organisms seemed to be the relative amount of tissue with a high affinity for these metals in each organism. The major ecological factor influencing accumulation of heavy metals seemed to be the relative amount of sediment association characteristic of each species. Invertebrates contained the highest levels of each metal, followed by bottom-oriented fish with a small proportion of muscle, while species of fish with a large percentage of muscle inhabiting the upper water column contained the lowest concentrations. Biomagnification of these four metals was not demonstrated. Significant bioaccumulation of lead, nickel, and cadmium in bone; and cadmium in the kidneys of fish was found to occur. Major biological uptake of lead, nickel, cadmium, and zinc in these organisms was via water and/ or sediment-water interaction. / Master of Science
500

Chemical, biological, and physical aspects of a small stream highly polluted by sewage over a long period of time

Beck, William McKinley January 1951 (has links)
The average individual is well aware of the need for ample supplies of water for domestic consumption and industrial use, for transportation, power, irrigation, and for recreation. Few, however, realize the scarcity and the value of this most versatile of a nation’s resources. The false impression of abundance that has long existed, created a certain sense of values which permitted misuse and abuse of the nation's supply of water. Increasing population and vast industrial growth leave created conditions that citizens can no longer ignore. In recent years considerable public opinion has been directed to the undesirable effects of extensive domestic and industrial pollution of the nation's waters. New legislation designed to control the uses of the country's waters and the abatement of pollution have been initiated and other programs arc proposed from time to time as public support increases. This thesis was designed to add to that fund of data upon which intelligent programs must necessarily be based. It presents some of the chemical, biological and physical aspects of a small, highly polluted stream, and an attempt was made to correlate the collected data sith the available information on the subjects involved. / Master of Science

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