• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 97
  • 93
  • 8
  • 8
  • 8
  • 8
  • 8
  • 4
  • 3
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • Tagged with
  • 222
  • 222
  • 101
  • 101
  • 39
  • 31
  • 27
  • 26
  • 22
  • 22
  • 22
  • 17
  • 16
  • 15
  • 15
  • 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.
31

Aquatic toxicology of selected rice insecticides, with special reference to their effects on fish culture in West Java, Indonesia

Koesoemadinata, Santosa January 1990 (has links)
Insecticides are widely used in SE Asian countries to control insect pests in rice, mainly stemborers (Chilo suppresallis) and brown plant hoppers (Nilaparvata lugens). The use of highly toxic insecticide compounds, however, is known to cause serious problem for fish culture in wet rice fields in many of these countries, particularly in Indonesia where this practice assumes a tremendous "house hold economic" importance, as well as being an essential part of the nation's inland aqua-culture production system. The laboratory and field experiments described were carried out to establish whether the application of five selected rice insecticides (fenobucarb, isoprocarb, buprofezin, diazinon and alphamethrin) would influence the growth and production of common carp fingerlings (Cyprinus carpio LINN.) raised in wet rice fields. Laboratory static toxicity tests revealed that the carbamate insecticides (fenobucarb and isoprocarb) were the least toxic insecticide compounds. The 96 hour Median Lethal Concentration (i.e the concentration that killed 50% of the test fish in 96 hours exposure period, under specified conditions) of these insecticides were 5.8mgl-1 and 5.3mgl-1, respectively. The synthetic pyrethroid insecticide alphamethrin was the most toxic insecticide with 96h-LC50 of 0.037mg1-1, while the organophosphate diazinon and the thiadiazin buprofezin showed intermediate toxicity to common carp (96h-LC50 = 2.3mgl-1 and 1.5mgl-1, respectively). A series of five field experiments were consecutively conducted, using 24 specially constructed rice field plots to accomodate the culture of common carp fingerlings for a period of 21 days. A single application of three dose regime, i.e 1/2X, 1 X and 2X of the recommended dose rate for insect control was given as treatment in each experiment. The survival of fish in all experiments were not significantly influenced by the insecticide treatment (P > 0.05). The growth rate and the production of fish biomass in rice fields treated with isoprocarb, buprofezin, diazinon and alphamethrin, were also found to be comparable with those in the untreated control plot (P > 0.05). In the rice fields treated with the highest dose rate of fenobucarb (1500gha-1 ,Al), the growth and production of fish were significantly lower than those in the untreated control rice fields (P < 0.05). Observations on the rice field biota revealed no definite pattern in the temporal changes of the population of zooplankton and macroinvertebrates both in the insecticide treated plots as well as in the untreated control plots. The minimum effects of the insecticide treatment to fish and rice field biota observed in the experiment were presumably due to several factors, mainly because a significant amount of the compounds were adsorbs by the rice field soil and aquatic vegetations and not onto the water, causing less toxicity, followed by the rapid flushing of the chemicals from the rice field system. The composition of the diet of common carp fingerlings in the rice field was found to be similar with those reported in the natural ponds, consisting mainly of aquatic insects (and their larvae), crustaceans, benthic macroinvertebrates and plant detritus. Based on the results of the present experiments, of the five insecticide compounds tested, diazinon and fenobucarb appeared to produce greater risk to fish when used in rice-fish farming. The use of agrochemicals in rice-fish farming should be carefully managed and controlled, using selected low toxic and non-persistent insecticides based on the result of laboratory and field toxicity tests.
32

Parabenos em água superficial : estudo analítico e aplicação em amostras ambientais /

Luizete, Milena Fontes. January 2013 (has links)
Orientador: Wagner Vilegas / Coorientador: Mary Rosa Rodrigues de Marchi / Banca: Eny Maria Vieira / Banca: Mario Sérgio Galhiane / Resumo: Produtos de cuidado pessoal são amplamente utilizados pela população. Em sua composição existe uma classe de compostos denominada parabenos que é utilizada pela sua propriedade bactericida e função de conservantes, sendo que tem sido apontados com possíveis alteradores endócrinos para a biota aquática. A literatura internacional relata a presença destes compostos em água naturais, em diversos países, muitas vezes em altas concentrações. No Brasil não há publicações nos quais os parabenos foram determinados em matriz aquosa. Considerando-se que pouca atenção tem sido dada à otimização e validação de método para análise de parabenos em amostras aquosas, neste trabalho desenvolveu-se à validação de método para a análise de parabenos em água de rio, fazendo-se o uso de cartuchos de poliestireno- divinilbenzeno (PSDVB) para extração em fase sólida (SPE) e cromatografia gasosa (CG) acoplada a espectrometria de massas (EM), em tandem, para a quantificação de metil, etil, propil, i-butil, e n-butil parabenos. A recuperação do método foi avaliada em amostras de água obtida no Ribeirão das Cruzes (Araraquara-SP) fortificadas em 3 níveis de concentração: 1; 0,5 e 0,1 ng L-1. A extração dos analitos (500 mL, n=3) resultou em valores de recuperação entre 56 - 100%, e CV menores que 11%. Foi avaliado o efeito de matriz, que indicou ser mandatória a utilização de curvas construídas na matriz para obtenção de dados confiáveis. O método validado foi aplicado com bom desempenho (recuperação do surrogate metilparabeno-d4 superior a 80% com CV <5%) às amostras de água do Ribeirão das Cruzes, a montante a jusante da Estação de Tratamento de Esgoto (ETE) de Araraquara. No ponto a montante todos os parabenos estiveram abaixo dos limites de detecção do método, no entanto para as amostras... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Personal care products are widely used by the population. In its composition there is a class of compounds called parabens which is used for its bactericidal property and function of preservatives, and has been identified with potential endocrine disrupters on aquatic biota. The international literature reports the presence of these natural compounds in water, in many countries, often in high concentrations. In Brazil there are no publications in which the parabens were determined in aqueous matrix. Considering that little attention has been paid to the optimization and validation of method for analysis of parabens in aqueous samples in this study was developed to validate the method for the analysis of parabens in river water, making the use of cartridges polystyrene-divinylbenzene (PSDVB) for solid phase extraction (SPE) and gas chromatography (GC) coupled with mass spectrometry (MS), tandem for the quantification of methyl, ethyl, propyl, i-butyl, and n-butyl parabens. The recovery of the method was evaluated in water samples obtained in Ribeirão das Cruzes (Araraquara-SP) fortified at 3 levels of concentrations: 1, 0.5 and 0.1 ng L-1. The extraction of analytes (500 mL, n = 3) resulted in recovery values between 56-100% and CV less than 11%. The effect of matrix, which indicated that it was mandatory to the use curves built into the array to obtain reliable data. The validated method was applied with good performance (recovery of surrogate methyl-d4 than 80% with CV <5%) to water samples from Ribeirão das Cruzes, upstream to downstream of Sewage Treatment Plant (WWTP) in Araraquara. At any point upstream parabens were below the detection limits method, however to samples collected downstream of the STP only the methyl and ethyl paraben were identified, only possible to quantify the methylparaben... (Complete abstract click electronic access below) / Mestre
33

Determinação espectrofotométrica da caboxiemoglobinemia em indivíduos expostos ocupacionalmente ao monóxido de carbono / Spectrophotometric determination of caboxiemoglobinemia occupationally exposed individuals in carbon monoxide

Malheiro, Ana Cristina Calhabeutt Gabriel da Costa 06 December 1991 (has links)
O monóxido de carbono (CO) constitui sério risco à saúde de indivíduos expostos a este gás. Os efeitos nocivos aparecem como conseqüência de sua combinação com a hemoglobina formando a carboxiemoglobina(COHb). A avaliação da exposição ao CO pela monitorização biológica é realizada, preferencialmente, pela determinação da carboxiemoglobinemia. O método espectrofotométrico proposto, para a determinação de COHb, utiliza a leitura na região Soret (420 e 432 nm) e fatores de calibração do espectrofotômetro. É realizado estudo comparativo entre o uso do CO obtido por reação química e o de cilindro de gás no preparo de solução 100% de COHb. O método apresenta boa precisão (coeficiente de variação de 2 e 6% para 4,98 e 1,01 % de COHb, respectivamente) e sensibilidade (0,50 % de COHb) adequadas à avaliação da exposição ao monóxido de carbono. A quantificação da COHb não é comprometida pelo teor hemoglobínico nem pela opalescência (lipemia) da amostra colhida no período pós-prandial. É apresentada a carboxiemoglobinemia em fumantes (n= 119) e não-fumantes (n= 189) que constituem 4 grupos de indivíduos expostos ocupacionalmente ao CO (n=209) e um grupo controle (n=99); e a análise estatística dos resultados (teste não-paramétrico). / Carbon monoxide (CO) is recognized as a high risk hazard to the health of exposed workers. Combining with hemoglobin it reduces the oxigen carrying capacity of the blood. The individual overall exposure may be assessed through the carboxyhemoglobin (COHb) content of blood samples, as a biological exposure index. A spectrophotometric method is proposed using measurements in the region Soret (420 - 432 nrn) together with calibration factors of the instrument. A comparative study is made between the use of CO from compressed gas cilinders and the CO delivered by a chemical reaction in preparing the saturated COHb solution. The method presents precision (coefficient of variation is 2 and 6% to 4,98 and 1,01% of COHb, respectively) and sensitivity (0,5% of COHb), which are adequate to the purpose. Hemoglobin and lipidic content of samples showed no effect in the COHb measurement. Carboxyhiemoglobin level of four groups of exposed workers (n = 209) and a control group (n = 99) among smokers (n = 115) and non-smokers (n = 189) were determinated using the method. The statistical analysis of the results are presented (non-parametric test).
34

Estudo da viabilidade de sedimentos formulados para a aplicação em estudos ecotoxicológicos e químicos: ênfase para os interferentes endócrinos 17alfa-etinilestradiol e 17beta-estradiol /

Arine, Ana Lúcia Fermino de Oliveira. January 2015 (has links)
Orientador: Renata Fracácio / Banca: Leonardo Fernandes Fraceto / Banca: Cleoni dos Santos Carvalho / Resumo: O uso de sedimentos formulados em laboratório vem sendo largamente adotado e recomendado por organizações de proteção ambiental e outras entidades internacionais de importância, como U.S.EPA, OECD e ASTM, devido, principalmente, à sua fácil reprodutibilidade por diferentes laboratórios e por ser livre de organismos e contaminantes indesejados no estudo. Visando a representatividade de ambientes lóticos tropicais, este estudo propôs analisar diferentes formulações de sedimento para a aplicação em estudo toxicológico de interferentes endócrinos (IE), sendo eles o 17β-estradiol (E2) e 17α-etinilestradiol (EE2). Foram avaliados os parâmetros oxigênio dissolvido, dureza e pH de 5 formulações de sedimento durante um período de 15 dias e a adaptação da espécie bentônica Hyalella azteca com relação aos parâmetros sobrevivência, crescimento e reprodução. A toxicidade do E2 e EE2, ambos à concentração de 30 ng/L, foi verificada sobre o organismo nectônico Ceriodaphnia dubia, exposto por 8 dias em solução extraída da formulação de sedimento que continha menor quantidade de matéria orgânica, contaminada em laboratório. Os parâmetros avaliados foram sobrevivência e reprodução, sendo utilizados os métodos estatísticos de Kruskal- Wallis, teste t e teste t por bioequivalência. O comportamento químico dos compostos foi analisado quanto ao tempo de degradação em ambiente com sedimento formulado (após 2, 24 e 48 horas de contato) e à capacidade de retenção ao sedimento após 2 horas de contato através de quantificação por cromatografia gasosa acoplada a espectrometria de massa (GC-MS). Os resultados mostraram que os sedimentos formulados contendo menores proporções de matéria orgânica (1 e 3% em massa) tiveram melhor estabilização em relação ao pH e também boa aceitação pela espécie H. azteca. Porém, o ambiente composto pelo mesmo sedimento não foi ideal para testes com C. dubia... / Abstract: The use of laboratory-formulated sediments have been widely adopted, and recommended by environmental protection organizations and other international agencies as USEPA, OECD, and ASTM, mainly for easy reproducibility by different laboratories, and for being free of unwanted contaminants and indigenous organisms. Aiming at the representation of tropical lotic environments, different sediment formulations were analyzed for use in toxicology studies of endocrine disruptors (EI), namely 17β-estradiol (E2) and 17α-ethinyl estradiol (EE2). Five different formulations were evaluated regarding dissolved oxygen, water hardness and pH over a period of 15 days, and on the adaptation of the benthic species Hyalella azteca regarding survival, growth, and reproduction parameters. The toxicity of E2 and EE2, both at the concentration of 30 ng/L, was observed in the nektonic organism Ceriodaphnia dubia, exposed to a solution extracted from spiked formulated sediment containing a minor amount of organic matter in a 8-days test. Survivability and reproduction parameters were evaluated using Kruskal-Wallis, t-test and bioequivalence t-test statistical methods. Chemical behavior of the compounds was analyzed regarding environmental degradation time in formulated sediment (after 2, 24, and 48 hours of contact), and sediment retention capacity after 2 hours of contact by quantification by gas chromatography-mass spectrometry (GC-MS). Results showed that the formulated sediments which contained smaller fractions of organic matter (1% and 3% dry weight) had better stabilization in relation to pH, and good acceptance by the species H. azteca. However, the formulated sediment environment was not ideal for C. dubia, which was therefore replaced by filtered interstitial water for E2 and EE2 tests. There was a statistically significant reduction in the number of newborns when exposed to control sediment and contaminants (Kruskal-Wallis, t-test, and bioequivalence ... / Mestre
35

Riskstudie av en förändrad användning av bromerade flamskyddsmedel / A study of risk in a changing use of brominated

Almberg, Ellinor January 2007 (has links)
<p>Denna uppsats är en kvalitativ studie om hur riskbilden ändras i en övergång från de idag förbjudna bromerade flamskyddsmedlen till andra alternativ med hänsyn till befintlig kunskap och effekter på människa och miljö. Användningen av bromerade flamskyddsmedel BFR har ökat stort sedan 50-talet. Idag uppskattas den totala produktionen till 200 000 ton/år. De fem vanligaste bromerade flamskyddsmedlen och de som främst tas upp i detta arbeta är: Tetrabrombisfenol A (TBBP-A), Penta-, Octa-, och Decabromdifenyleter (PBDE) samt Hexabromcyklodekan (HBCDD). Dessa ämnen finns i många olika varianter där egenskaperna kan variera. Några karaktäristiska egenskaper för dem alla är låg flyktighet, hög löslighet i fett och att de är långlivade. Bromerade flamskyddsmedel används i allt från textilier, byggmaterial till elektriska produkter och i kretskort till datorer. Bromerade flamskyddsmedel kan läcka ut i miljön under hela dess produktionscykel. Varje år frigörs tonvis BFR till den Europeiska miljön.</p><p>PBDE har påträffats i många djur spridda över stora delar av världen. De negativa egenskaperna anses inte tillräckligt starka för ett EU-förbud av TBBP-A, HBCDD och DecaBDE. På djur har dock effekter som beteendeförändringar på råttor, förändringar i hormonbalans och försämrad inlärningsförmåga upptäckts. Halter av BFR har även funnits i mänsklig bröstmjölk, vilket är en stor riskfaktor då små barn och foster är särskilt utsatta. Utvecklingen av det centrala nervsystemet är till exempel mycket komplex där förändrad hormonbalans kan ha förödande konsekvenser.</p><p>De fem Svenska myndigheter som har kontaktas anser alla att användningen av bromerade flamskyddsmedel är problematiskt men för att minska den risken krävs främst åtgärder på EU nivå. De olika verkens uppdrag har varierande inriktningar men ska samtliga antigen arbeta för ökad säkerhet, ökad information eller för en hållbar samhällsutveckling – något som försvåras av det faktum att användningen av BFR medför en rad osäkerheter. Det finns många faktorer som kan verka för en ökad, respektive en minskad användning av BFR. Lagar och förordningar såsom REACH och RoHS direktivet kan verka hämmande på användningen samtidigt som starka brandskyddskrav och lobbying kan göra att marknaden istället växer. Det finns alternativ till bromerade flamskyddsmedel både tekniska lösningar där säkerheten finns i produktens utformning men även nya tekniker att flamskydda plaster.</p><p>Slutsatsen är att; risken minskar i och med förbud som förbjuder likartade ämnen, dock inte tillräckligt snabbt. Kunskapsnivån stiger när det gäller befintliga ämnen men när det gäller bromerade alternativ så finns det fortfarande för lite kunskap.</p> / <p>This paper is a qualitative study about the changing image of risk when the use of brominated flame retardants BFR goes from prohibited ones, to alternative flame retardants, with the account of existing knowledge and the effects on humans and the environment. The use of brominated flame retardants has been going through a large increase since the 1950s. Today the global production estimates 200 000 ton each year. The five most common BFR and those the focus lay on in this paper are: Tetrabromobisphenol A TBBP-A, Penta-, Octa- and Decabromodiphenylether (PBDE) and Hexabromocyclododecane HBCDD. These substances are all exist in many different variants where the properties could vary. Some characteristic properties for all of them are low general volatility but high solubility in fat and that they are persistent. BFR are used in many different areas like textiles, building material, electrical products and in printed circuit cards for computers. BFR can leak out during the products whole life-cycle. Each year, tonnes of BFR release to the European environment.</p><p>PBDE have been discovered in animals, scattered over big parts of the world. The evidence of the negative effects is not considered to be strong enough for a full ban of TPPP-A, HBCDD or DecaBDE in the European Union. However effects like impairing learning functions, changes in the spontaneous behaviour and different hormone levels have been detected in tests on laboratory animals. Levels of BFR have also been found in human breast milk. This is a big risk factor because small children and embryos are particularly sensitive. The neurological development is for example very complex and a changing hormone level could have devastating consequences.</p><p>All the five Swedish authorities that have been contacted in this paper consider the usage of brominated flame retardants as a problem and have the opinion that the solution lay in measures in a European Union level. The agencies have different commissions but all of them work, either for an increased security and information level, or for a sustainable society development. The fact that the use of BFR involves many insecurities, make their tasks even more difficult to reach. Different circumstances can lead to either an increase or a decrease usage of BFR. Legislation and directives can inhibit the use of BFR whereas lobbying and fire safety demands could have the opposite effect. Alternative fire retardants have been developed; both technical solutions where the safety lay in the design of the product but also new way of protect plastics from fires.</p><p>The conclusion is; the risk will decrease if legislation prohibits a whole group of chemicals, but not fast enough. The level of knowledge about the existing chemicals is rising but the knowledge about the brominated options is still to low.</p>
36

Riskstudie av en förändrad användning av bromerade flamskyddsmedel / A study of risk in a changing use of brominated

Almberg, Ellinor January 2007 (has links)
Denna uppsats är en kvalitativ studie om hur riskbilden ändras i en övergång från de idag förbjudna bromerade flamskyddsmedlen till andra alternativ med hänsyn till befintlig kunskap och effekter på människa och miljö. Användningen av bromerade flamskyddsmedel BFR har ökat stort sedan 50-talet. Idag uppskattas den totala produktionen till 200 000 ton/år. De fem vanligaste bromerade flamskyddsmedlen och de som främst tas upp i detta arbeta är: Tetrabrombisfenol A (TBBP-A), Penta-, Octa-, och Decabromdifenyleter (PBDE) samt Hexabromcyklodekan (HBCDD). Dessa ämnen finns i många olika varianter där egenskaperna kan variera. Några karaktäristiska egenskaper för dem alla är låg flyktighet, hög löslighet i fett och att de är långlivade. Bromerade flamskyddsmedel används i allt från textilier, byggmaterial till elektriska produkter och i kretskort till datorer. Bromerade flamskyddsmedel kan läcka ut i miljön under hela dess produktionscykel. Varje år frigörs tonvis BFR till den Europeiska miljön. PBDE har påträffats i många djur spridda över stora delar av världen. De negativa egenskaperna anses inte tillräckligt starka för ett EU-förbud av TBBP-A, HBCDD och DecaBDE. På djur har dock effekter som beteendeförändringar på råttor, förändringar i hormonbalans och försämrad inlärningsförmåga upptäckts. Halter av BFR har även funnits i mänsklig bröstmjölk, vilket är en stor riskfaktor då små barn och foster är särskilt utsatta. Utvecklingen av det centrala nervsystemet är till exempel mycket komplex där förändrad hormonbalans kan ha förödande konsekvenser. De fem Svenska myndigheter som har kontaktas anser alla att användningen av bromerade flamskyddsmedel är problematiskt men för att minska den risken krävs främst åtgärder på EU nivå. De olika verkens uppdrag har varierande inriktningar men ska samtliga antigen arbeta för ökad säkerhet, ökad information eller för en hållbar samhällsutveckling – något som försvåras av det faktum att användningen av BFR medför en rad osäkerheter. Det finns många faktorer som kan verka för en ökad, respektive en minskad användning av BFR. Lagar och förordningar såsom REACH och RoHS direktivet kan verka hämmande på användningen samtidigt som starka brandskyddskrav och lobbying kan göra att marknaden istället växer. Det finns alternativ till bromerade flamskyddsmedel både tekniska lösningar där säkerheten finns i produktens utformning men även nya tekniker att flamskydda plaster. Slutsatsen är att; risken minskar i och med förbud som förbjuder likartade ämnen, dock inte tillräckligt snabbt. Kunskapsnivån stiger när det gäller befintliga ämnen men när det gäller bromerade alternativ så finns det fortfarande för lite kunskap. / This paper is a qualitative study about the changing image of risk when the use of brominated flame retardants BFR goes from prohibited ones, to alternative flame retardants, with the account of existing knowledge and the effects on humans and the environment. The use of brominated flame retardants has been going through a large increase since the 1950s. Today the global production estimates 200 000 ton each year. The five most common BFR and those the focus lay on in this paper are: Tetrabromobisphenol A TBBP-A, Penta-, Octa- and Decabromodiphenylether (PBDE) and Hexabromocyclododecane HBCDD. These substances are all exist in many different variants where the properties could vary. Some characteristic properties for all of them are low general volatility but high solubility in fat and that they are persistent. BFR are used in many different areas like textiles, building material, electrical products and in printed circuit cards for computers. BFR can leak out during the products whole life-cycle. Each year, tonnes of BFR release to the European environment. PBDE have been discovered in animals, scattered over big parts of the world. The evidence of the negative effects is not considered to be strong enough for a full ban of TPPP-A, HBCDD or DecaBDE in the European Union. However effects like impairing learning functions, changes in the spontaneous behaviour and different hormone levels have been detected in tests on laboratory animals. Levels of BFR have also been found in human breast milk. This is a big risk factor because small children and embryos are particularly sensitive. The neurological development is for example very complex and a changing hormone level could have devastating consequences. All the five Swedish authorities that have been contacted in this paper consider the usage of brominated flame retardants as a problem and have the opinion that the solution lay in measures in a European Union level. The agencies have different commissions but all of them work, either for an increased security and information level, or for a sustainable society development. The fact that the use of BFR involves many insecurities, make their tasks even more difficult to reach. Different circumstances can lead to either an increase or a decrease usage of BFR. Legislation and directives can inhibit the use of BFR whereas lobbying and fire safety demands could have the opposite effect. Alternative fire retardants have been developed; both technical solutions where the safety lay in the design of the product but also new way of protect plastics from fires. The conclusion is; the risk will decrease if legislation prohibits a whole group of chemicals, but not fast enough. The level of knowledge about the existing chemicals is rising but the knowledge about the brominated options is still to low.
37

Toxicity of Prudhoe Bay crude oil to mallard duck (<i>anas platyrhynchos</i>) embryos

Lusimbo, Wanjala Simiyu 01 January 1999 (has links)
This study was undertaken to assess rates and timing of mortality and hatchability, to identify pathological changes and compare them to those observed in chicken embryos, and to determine whether mallard duck chorioallantoic membrane (CAM) is a target organ of toxicity of Prudhoe Bay crude oil (PBCO). Mortality and hatchability were determined in embryos exposed to 10[mu]l of PBCO on days 3, 6, 9 and 12 of incubation. Pathological changes in embryos and the CAM, hematological parameters and body and plasma calcium concentration were assessed in live embryos exposed to PBCO on day 12. Oil-exposed embryos had high mortality, low hatchability and high prevalence of pathological changes. Mortality was characterized by initial death that coincided with development and maturation of the CAM and a sublethal effect that resulted in live, mature embryos, which were unable to hatch. This mortality at hatching contributed greatly to total mortality. Lesions included hepatic and renal necrosis, liver enlargement, subcutaneous edema, reduced body weight and ratio of body weight to fresh egg weight, short crown-rump, third toe and metatarsal lengths, depletion of lymphocytes in the bursa of Fabricius, renal hematopoiesis, and diffuse changes in the CAM which included necrosis and hyperplasia, of chorionic epithelium, soft swelling of mesenchymal cells, hemorrhages and reduced vascular density. There also were high proportions of reticulocytes and polychromatophilic and primary erythrocytes. Prevalence of lesions in the CAM was greatest during the stage of acute toxicity, suggesting that injury to the CAM may have a role in acute oil. toxicity. The distribution of lesions in the CAM suggests a direct effect on the CAM cells of toxic components or their metabolites. Injury to the CAM did not affect its role in mobilization of calcium from the eggshell. Body and plasma calcium in oil-exposed and control embryos were not different. Embryos exposed to PBCO did not develop anemia nor any damage to the red blood cells. The spectrum of morphological changes in oil-exposed embryos suggests retarded and altered development The rate and timing of mortality and pathological changes in oil-exposed mallard embryos were similar to those reported in oil-exposed chicken embryos.
38

Sorption of selected endocrine disrupters by synthetic membrane vesicles and effects of natural organic matter

Yamamoto, Hiroshi. January 2002 (has links)
Thesis (Ph. D.)--University of Texas at Austin, 2002. / Vita. Includes bibliographical references. Available also from UMI Company.
39

Sorption of selected endocrine disrupters by synthetic membrane vesicles and effects of natural organic matter

Yamamoto, Hiroshi, 1973- 10 May 2011 (has links)
Not available / text
40

Effects of chiral contaminants to aquatic organisms pharmaceuticals as model compounds for enantiomer specific ecological hazard assessment /

Stanley, Jacob K. Brooks, Bryan William, January 2006 (has links)
Thesis (Ph.D.)--Baylor University, 2006. / Includes bibliographical references (p. 93-103).

Page generated in 0.106 seconds