• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 1294
  • 774
  • 167
  • 48
  • 24
  • 23
  • 20
  • 17
  • 15
  • 15
  • 15
  • 15
  • 15
  • 15
  • 14
  • Tagged with
  • 3044
  • 3044
  • 733
  • 673
  • 651
  • 648
  • 359
  • 341
  • 239
  • 231
  • 216
  • 202
  • 199
  • 196
  • 188
  • 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

Estudos limnológicos de balneabilidade no Parque Natural Municipal Cachoeira da Marta (Botucatu, SP, Brasil): relação com possíveis fontes poluidoras

Traficante, Daniela Polizeli [UNESP] 22 June 2011 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:22:23Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-06-22Bitstream added on 2014-06-13T19:48:42Z : No. of bitstreams: 1 traficante_dp_me_jabo.pdf: 1568154 bytes, checksum: e9230b2e4ff60845b3fe6ffebb26eea6 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Universidade Estadual Paulista (UNESP) / O município de Botucatu está localizado na região centro-sul do Estado de São Paulo, a 230 km da capital, com altitudes variando de 400 a 950 metros. Essa geomorfologia propicia a formação de quedas d’água, cujo relevo chamado “Cuesta” é divisor de águas entre a Bacia do Rio Paranapanema e a Bacia do Rio Tietê. É na microbacia do Alto Rio Capivara (Bacia do Tietê) onde está situado o Parque Natural Municipal Cachoeira da Marta, Unidade de Conservação de Proteção Integral, conhecido como “Parque da Marta”, tendo como principal atrativo a Cachoeira da Marta (38 metros de queda d’água), sendo um local muito procurado para a prática de atividades de lazer e ecoturismo. A Cachoeira é abastecida pelas águas do Córrego do Roseira, tendo como principal afluente o Córrego do Canela, que ao se juntarem, formam o Rio Capivara. O presente estudo teve como objetivos avaliar as condições limnológicas de balneabilidade da Cachoeira da Marta em interface com as possíveis fontes potenciais de poluição para propor medidas de recuperação e conservação através da analise dos parâmetros físico-químicos (TºC da água, pH, Condutividade elétrica, Oxigênio dissolvido, Nitrogênio total e Fósforo total) e microbiológicos (Coliformes totais e termotolerantes). As coletas de água foram bimensais durante 12 meses, de Junho/2009 a Maio/2010, em 5 pontos amostrais diferentes, sendo 3 pontos (P1, P2 e P3) no Córrego do Roseira, 1 ponto na junção dos Córregos do Roseira e Canela (P4) e 1 ponto no Córrego do Canela (P5). Os P2, P3 e P4 se localizavam dento do Parque da Marta. Para a comparação das médias nos pontos amostrais foi realizada a analise de variância (ANOVA) seguidas do Teste de Tukey (Tukey’s Studentized Range – HSD) para as variáveis que apresentaram distribuição normal e o teste não paramétrico de Kruskal-Wallis para as variáveis... / Botucatu is a municipality located in the central south region of Sao Paulo State, 230 km away from de the capital at altitudes ranging from 400 to 950 meters. The landforms in this region favor the formation of waterfalls; the relief, called “Cuesta” is a water divisor for the watersheds of Paranapanema and Tiete Rivers. In the micro-watershed of Capivara Highest River (Tiete watershed) is located the Marta’s Waterfall Natural Park, a protected area, know as “Marta’s Park”, where the Marta’s waterfall (38 meters by heigh) is the principal atractive and have been searched for tourism and leisure activities. The waterfall is supply by the Roseira River and his principal tributary is the Canela River and when they to join up, they transformer in the Capivara River. This study aimed to evaluate the limnological conditions for the bathing water quality by the Marta’s Waterfall associated with the possible potential source by pollution and suggest conservation and recovery measures through the physicochemical (water temperature (ºC), pH, eletric condutivity, dissolved oxigen, total nitrogen, total phosporus) and microbiological parameters (total and thermotolerants coliforms). The water samples were bimonthly collected for 12 months, between June/2009 ande May/2010, in different sites over the streams , in 5 diffrents collections sites, 3 sites (P1, P2 e P3) are inside in Roseira River, 1 site in the joiing at Roseira and Canela Rivers (P4) e 1 site located in Canela River (P5). For comparison of medias in the collections sites was realized the variance analisys (ANOVA) followed by the Tukey’s Studentized Range (HSD) for the medias that showed normal distribution and the nonparametric Kruskal-Wallis test for the medias that doesn’t showed normal distribuition, both in the 5% significance level. In the collection sites 1 and 5 were founded medias for dissolved oxigen... (Complete abstract click electronic access below)
72

Calculating Willingness-To-Pay As a Function of Biophysical Water Quality and Water Quality Perceptions

Silva, Carlos G. 01 May 2014 (has links)
When estimating economic value associated with changes in water quality, recreation demand models typically depend upon either (i) biophysical measures of water quality as collected by natural scientists or (ii) the perception of water quality by recreationists. Models based upon biophysical metrics (such as oxygen concentration, pollutant concentrations, Secchi depth measurements, etc.) operate on the assumption that people can perceive and respond to these metrics, or respond to factors that are, indeed, correlated with the biophysical measure. Economists have often estimated willingness-to-pay (WTP) measures associated with unit changes in biophysical measures without examining the degree to which the measures are truly correlated with perceptions. Recreation demand models that are based upon respondents’ perceptions of water quality necessarily assume that perceptions correlate well with the measures used by scientists to evaluate water quality. Again, WTP for unit changes in perceptions have been estimated without examining the relationship to the underlying biophysical measures. The relationship between biophysical metrics and perceptions is rarely addressed, yet it has profound implications for water quality management and policy. Consider a federal or state agency wishing to manage the quality of its waters in an economically efficient way. Through mandated water quality monitoring regulations, an agency may have many years of biophysical measurements, but these measures are in no way linked to people’s perceptions of water quality and, thus, to WTP. Using biophysical measures of water quality and recreation use data recently collected in Utah, this study links technical measures of water quality at a water body to survey respondents’ perceptions of water quality at the same site. This approach is akin to estimating an ecological production function wherein biophysical measures are “inputs” to water quality perceptions (the output). Truncated Negative Binomial models of water-based recreation are used to estimate welfare effects of changes in water quality as measured through (i) unit changes in biophysical measures, (ii) unit changes in perceptions, and (iii) unit changes in biophysical as they change perceptions through the ecological production function.
73

A questionnaire and a concentrator sampling technique used to evaluate water quality degradation in water distribution systems

Manning, Deborah Kathleen January 1982 (has links)
Two approaches for the examination of microbially-caused degradation of water quality within water distribution systems were considered: the results of a questionnaire were analyzed and a sampling technique utilizing a concentrator was evaluated. A questionnaire, completed by water treatment plant operators in Virginia, was analyzed to ascertain what complaints regarding water quality were being received and what the causes of the complaints were. The most frequently reported complaints were those of taste and odor. Although they were not the sole factor, it appears nuisance bacteria were causative agents in degradation problems related to turbidity and red water. The Pellicon cassette system concentrator was evaluated for use during sampling in water distribution systems. The evaluation included determining the range of percent recovery in the retentate to be expected and the factors affecting this recovery. Thirty to sixty percent recovery of bacteria (Pseudomonas cepacia or Escherichia coli) in the retentate can be expected. The percent reduction in volume was the system parameter which most affected the percent recovery. / Master of Science
74

Periphyton growth in the Waipara River, North Canterbury

Hayward, Shirley January 2003 (has links)
Periphyton was monitored monthly at four sites on the Waipara River from July 1999 to January 2002. Interactions with river flows, nutrients and invertebrates were examined to determine how these factors controlled periphyton development. Comparison of the Waipara River to other New Zealand streams indicated that periphyton biomass at the uppermost site (Site 1) was generally low to moderate. Further downstream, moderate to high biomass occurred at sites 2 and 4. Biomass at Site 3 was generally low, although some very high values occurred on occasions. Periphyton biomass at sites 2 and 4 exceeded periphyton guidelines for the protection of aesthetic/recreational values at least once during each full year monitored. In contrast, the guidelines were rarely exceeded at Site 1. Dissolved inorganic nutrients were generally poor indicators of the nutrient status of the river because of plant uptake. Cellular N and P values indicated nutrient enrichment at sites 2 and 4, which correspondingly had the highest biomass values. Conductivity tended to positively correlate with temporal and spatial patterns in periphyton biomass and was useful as a surrogate indicator of nutrient supply regimes. It correlated negatively with river flows, indicating higher nutrient concentrations may occur during reduced flows. Notable differences occurred in biomass development between periods of contrasting flow regimes. In particular, annual mean and maximum biomass at the three downstream sites was considerably higher during a period of low stable flows compared to a period of higher base flows. However, at the uppermost site, differences in biomass between these periods were much less pronounced. Invertebrate densities increased significantly with increasing periphyton biomass at the three downstream sites. There was little indication that invertebrates had any major control on periphyton biomass at these sites. However, at the uppermost site, although the invertebrate densities were generally much lower than at the other sites, they are more likely to have a controlling influence on periphyton biomass. Overall, the nutrient supply regime of the Waipara River is the primary controller on biomass development. Flow regimes (both frequency of disturbance and extent of low flows) operate as secondary controls of biomass.
75

Whole lake and mesocosm studies on the role of nutrients and zooplankton grazing in a system of shallow and deep lakes

Beklioglu, Meryem January 1995 (has links)
No description available.
76

Factors affecting coagulation of turbid water and softening hardwater with Moringa oleifera seed extracts

Muyibi, Suleyman Aremu January 1995 (has links)
No description available.
77

Nitrate removal from groundwater using a rotating biological contactor with alternative carbon sources

Mohseni-Bandpi, Anoushiravan January 1996 (has links)
No description available.
78

Nitrate transport component for SHETRAN catchment modelling system

Birkinshaw, Stephen J. January 1997 (has links)
No description available.
79

The distribution and population dynamics of Corixidae

Feakes, Karl Anthony January 1996 (has links)
No description available.
80

Paint wastewater treatment using Fe3+ and Al3+ salts

Ntwampe, Irvin Oupa Lesele 10 September 2014 (has links)
A PhD thesis submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Doctor of Philosophy in Engineering. Johannesburg / This study involves the investigation of the paint wastewater treatment using inorganic coagulants such as FeCl3, Fe2(SO4)3, AlCl3 and Al2(SO4)3 in a jar test during rapid and slow mixing for 250 and 100 rpm respectively, settled the samples, measure the pH and turbidity. The pH, turbidity and area covered by the flocs were used as measurements in this study to determine the quality of treated paint wastewater. In the first experiment, 200 mL sample of 169.2 g of paint wastewater dissolved in 1L of potable water was poured into six 500 mL glass beakers sample dosed with FeCl3 only, combined FeCl3 and Ca(OH)2 or Mg(OH)2 as well as FeCl3-Ca(OH)2 and FeCl3-Mg(OH)2 polymers respectively, run through a jar test with rapid and slow mixing. The supernatant was extracted after 1 hour settling to measure the pH and turbidity. The observations showed that combined FeCl3 and Mg(OH)2 as well as FeCl3-Mg(OH)2 polymers yielded identical and slightly higher turbidity removal than combined FeCl3 and Ca(OH)2 and FeCl3-Ca(OH)2 polymers. Another batch of experiments was carried out using the same metal salts with Ca(OH)2 and Mg(OH)2 respectively for pH adjustment. The samples were treated in a jar test using various dosing patterns such as dosages, dosing prior or during mixing, combined dosages interchangeably, retention time. A third batch of experiments was carried out by dosing synthetic polymers of FeCl2-Ca(OH)2 and FeCl2-Mg(OH)2 respectively using similar dosing patterns. The results obtained in first set of experiments, were Fe3+ and Al3+ salts were added in paint wastewater showed that the changing pH correlates with turbidity removal. It was also observed that dosing prior or during mixing do not play any significant role in wastewater treatment. Another observation showed that flocculation of the paint wastewater dosed with FeCl2-Ca(OH)2 or FeCl2-Mg(OH)2 polymers do not show correlation between the pH and turbidity, which indicates that the pH is not an indicator of turbidity removal in a more alkaline solutions such as paint wastewater. A second study was carried out using the same paint wastewater samples (200 mL) and samples dosed with Fe3+ and Al3+ salts treated in a jar test and immediately two drops of supernatant were placed on a microscope slide and view it under a microscope connected to a camera, images were captured after 1, 60 and 90 minutes respectively (Exp A). Samples were prepared from the original paint wastewater and the standard solution of Fe3+ and Al3+ in a small scale using identical metal salt/paint wastewater volume ratios as above. Two drops from the paint wastewater and metal salt solution were place on a microscope slide and images were captured as above using 1, 60 and 90 minutes respectively (Exp B). All the visuals were printed and the visuals obtained in Exp A were compared with their corresponding visuals in Exp B in accordance with time. The results obtained showed that the percentage area covered by flocs treated in a jar test (Exp A) correlates linearly with the percentage area covered by the flocs from a microscope slide (Exp B). The results obtained using this technique also confirm that the reaction between the drops of a sample and the drops of coagulant produces well-developed solid hydrolysis species. A third study was carried out by pouring 200 mL of the same paint wastewater samples into six 500 mL glass beakers and with Fe3+ and Al3+ salts as above, run through a jar test during 30, 45 and 60 seconds rapid mixing (250 rpm) only for 2 minutes respectively. The samples settled for 1 hour, and then pH and turbidity were measured. Another experiment was carried out using the similar method as above with samples run through a jar test at 250 rpm during 30, 45 and 60 seconds rapid mixing (250 rpm) for 2 minutes followed by slow mixing (100 rpm) for 10 minutes (combined rapid and slow mixing). The samples settled for 1 hour, and then pH and turbidity were measured. The results obtained from the jar tests (comparison between flocculation during rapid mixing only and combined rapid and slow mixing) showed that the pH in the samples with rapid mixing shows an insignificant change compared to their corresponding samples with combined rapid and slow mixing; turbidity in the samples with 30, 45 and 60 seconds rapid mixing showed that most of the flocs are formed within 30 seconds. There is a correlation between the pH and turbidity when paint wastewater is dosed with Fe3+ or Al3+ metal ions in their respective metal salts without pH adjustment. The Fe3+ and Al3+ of the same concentration yield a similar pH and turbidity trend.

Page generated in 0.033 seconds