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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.
101

Écotoxicité de la deltaméthrine et du malathion sur différentes souches de "Daphnia magna" (Crustacea, Cladocera) : apport de la protéomique dans la recherche de nouvelles cibles cellulaires / Ecotoxicity of deltamethrin and malathion with diverse strains of Daphnia magna (Crustacea, Cladocera) : contribution of proteomics investigation in the search for new cellular targets

Toumi, Héla 30 September 2013 (has links)
L’objectif de ce travail a consisté à évaluer différents effets écotoxiques de la deltaméthrine et du malathion sur trois souches du crustacé cladocère Daphnia magna. Deux de ces 3 souches appartiennent au même clone A (souches 1 et 3), ce qui a permis d’observer des différences de sensibilité inter- et intra-clonale. Les tests d’écotoxicité aiguë (48h) ont révélé, aussi bien pour la deltaméthrine que pour le malathion, que la souche 1 est plus sensible que la souche 2, elle-même plus sensible que la souche 3. Les tests chroniques (21 jours) ont montré que le critère commun majoritairement affecté par les deux pesticides est le nombre de nouveaux nés par adulte. Ces tests ont confirmé la sensibilité de la souche 1. La deltaméthrine et le malathion sont embryotoxiques puisque l’exposition des daphnies aux fortes concentrations de deltaméthrine et de malathion a induit des malformations. Pour ces effets, la souche 1 est également plus sensible que la souche 2, elle-même plus sensible que la souche 3. Nous avons aussi observé l’apparition de mâles, mais uniquement dans la descendance de la souche 1 exposée à la deltaméthrine. Le dosage de l’activité spécifique de l’acétylcholinestérase (AChE), pour les deux insecticides, a montré une inversion de l’ordre de sensibilité des souches. L’AChE, biomarqueur d’exposition et d’effet, peut être donc considérée aussi comme biomarqueur de susceptibilité. L’analyse protéomique a permis de révéler plusieurs cibles cellulaires de la deltaméthrine chez la souche 1 par rapport à la souche 2. Elle est surtout venue confirmer la plus grande sensibilité de la souche 1 par rapport à la souche 2. L’ensemble de ces résultats rappelle que le facteur génétique est une source de variation et souligne les perspectives offertes par l’analyse protéomique / The aim of this work was to evaluate different ecotoxic effects of deltamethrin and malathion on three strains of the cladoceran Daphnia magna. Two of the three strains belong to the same clone A (strains 1 and 3), which allowed to observe differences in inter-and intra-clonal sensitivity. The acute ecotoxicity tests (48h) showed for both deltamethrin and malathion, that one strain is more sensitive than strain 2, itself more sensitive than strain 3. Chronic tests (21days) showed that the common criterion mainly affected by both pesticides is the number of neonates per adult. These tests confirmed the sensitivity of the strain 1. Deltamethrin and malathion are embryotoxic as daphnid exposure to high concentrations of deltamethrin and malathion induced malformations. For these effects, strain 1 is also more sensitive than strain 2, itself more sensitive than strain 3. We also observed the appearance of males, but only in the offspring of the strain 1 exposed to deltamethrin. The determination of the specific activity of acetylcholinesterase (AChE), for both insecticides, showed a reversal of the order of susceptibility testing. Thus, as a biomarker of exposure and effect, AChE can also be considered as a biomarker of susceptibility. Proteomic analysis revealed several cellular targets of deltamethrin in strain 1 compared to strain 2. It confirms the greater sensitivity of strain 1 compared to strain 2. All these results point out that the genetic factor is a source of variation and highlight the opportunities offered by proteomic analysis
102

Ekotoxikologické posouzení bodových zdrojů znečištění v ekosystému / Ecotoxicological Assessment of Point Pollution in the Ecosystem

Doležalová, Šárka January 2018 (has links)
The main subject of this dissertation is the ecotoxicological evaluation of significant point sources of pollution. These include wildfires and wide fires of factories and also industrial and urban wastewater treatment plants. The local application of pyrolytic product obtained from sewage sludge as the point source of pollution was also included in the thesis. Tests in aquatic and contact arrangement with using both water and soil organisms for ecotoxicity evaluation of selected matrices were chosen. Crustaceans Thamnocephalus platyurus, Daphnia magna Straus and sea bacteria Vibrio fischeri were selected as representative organisms of water animals. Duckweed Lemna minor was chosen as water plant. Further collembola Folsomia candida and earthworm Eisenia fetida were chosen as representatives of soil animals. Finally onion Allium cepa L. and mustard Sinapis alba are representatives of terrestrial plants. Submitted thesis deals about analytes of interest, their properties and ways of distribution to the environments. The output of the thesis is a comprehensive assessment of the effects of selected point sources of pollution on aquatic and terrestrial ecosystems organisms and ecotoxicological risks assessment. The fire extinguishing agents have been proven to be the most stressful substances for all selecteded organisms.
103

Posouzení účinnosti pokročilých oxidačních procesů prostřednictvím testů ekotoxicity / Assessment of the effectiveness of advanced oxidation processes via ecotoxicity tests

Procházková, Petra January 2019 (has links)
Recently, an increasing problem in wastewater treatment is the insufficient removal of organic pollutants. These substances can be toxic to the environment already in a small amount, either acutely or chronically. The goal is therefore to develop of technologies that ensure their effective removal. One possibility is to use advanced oxidation processes. Advanced oxidation processes work on the principle of non-selective oxidation mediated by OH radicals. Several methods such as O3/H2O2 (Peroxone), UV/H2O2 or Fenton´s reaction can be used to generate them. The aim of this thesis was to evaluate the effectiveness of the used advanced oxidation processes in wastewater treatment via ekotoxicity tests. Wastewater samples treated with advanced oxidation processes on the pilot unit showed low values of acute toxicity for selected test organisms (D. magna, T. platyurus, S. alba, L. minor). For the sample of waste water that was treated with the UV/H2O2 on AOP laboratory unit, there was an increase in acute toxicity on the testing organism D. magna and L. minor. The similar effect was observer in the tests with the D. magna with the model samples treated with the same method, while the tests on the L. minor showed a reduction in toxicity.
104

Posouzení účinnosti čištění odpadních vod pomocí testů ekotoxicity / Assessment of the efficiency of wastewater treatment plant using ecotoxicity tests

Urminská, Barbora January 2015 (has links)
The possibilities of environmental pollution control are increasing and more advanced wastewater treatment methods are being emphasized, as well as more specific control of contaminants presence in treated waters. That is why it becomes relevant to perform not only chemical analysis but also ecotoxicological bioassays as the means of evaluation of biological effects caused by wastewater discharges to ecosystems. No wastewater treatment plant is able to treat the water perfectly – it can only decrease the pollution level to an acceptable value. Therefore it is important to find out if the treatment process is sufficient to provide a satisfactory decrease of ecotoxicity and also what effects to the organisms in recipient will be caused by wastewater discharges. The thesis is focused on the evaluation of wastewater ecotoxicity. In the experimental part of the thesis, wastewater samples were collected at four wastewater treatment plants in the Czech Republic. At one of them also the sludge samples were taken. The aim was to evaluate the efficiency of wastewater treatment by selected ecotoxicological bioassays. The results have shown that the efficiency of wastewater treatment plants with secondary treatment is sufficient to reduce acute toxic effects to the minimum. Average toxicity removal was over 80 % at three of four evaluated wastewater treatment plants. At the fourth WWTP it was 41 %, however, at this WWTP high efficiency of treatment is not necessary.
105

Studium hlavních aspektů mykoremediace - vliv biodostupnosti, biodegradace a toxicity organických polutantů / Study of main mycoremediation aspects - effect of bioavailability, biodegradation and toxicity of organic pollutants

Čvančarová, Monika January 2014 (has links)
Many organic compounds are released to the environment and can be harmful to living organisms. These compounds are often persistent and toxic. Some are mutagens, carcinogens, endocrine disruptors or they can cause an increase in bacterial resistance. They tend to accumulate in nature and their transformation is a long-term process. Therefore, various remediation techniques are needed for decontamination. Remediation and bioremediation processes depend on many factors which should be critically evaluated. This dissertation thesis studies the relationship between bioavailability, biodegradation and toxicity of polychlorinated biphenyls, polycyclic aromatic hydrocarbons and fluoroquinolone antibiotics. These compounds of different origin, character and properties were degradated by ligninolytic fungi. Desorption behaviour of pollutants from historically contaminated sites, degradation potential of ligninolytic fungi, ongoing degradation mechanisms, transformation products and their toxicity were studied as important factors for evaluation of mycoremediation and its environmental impact. The results show that determination of bioaccessible fraction by sequential supercritical fluid extraction is very useful for precise prediction of biodegradability of pollutants. The evidence that ecotoxicity and...
106

Využití tkáňových linií pro toxikologii v životním prostředí / Utilization of tissue cultures for toxicology of the environment.

Polanská, Daniela January 2020 (has links)
5 Abstract Five substances from the group of so-called personal care products, known for their low degradability and regular environmental detection, were tested for toxicity using two fish tissue lines (RTgill-W1 a RTG-2) isolated from rainbow trout (Oncorhynchus miykiss). The tested substances were hexadecylpyridinium chloride (HDP), chlorhexidine (CHX), octenidine (OCT), thymol (THM) and triclosan (TCS). A cell viability assay was performed with each of these compounds using Alamar Blue ™ (AB), 5-carboxyfluorescein diacetate acetoxymethyl ester (CFDA-AM) and neutral red (NR) protocols. The results were used to construct dose-response curves along with an EC50 value for each of these substances. The EC50 values ranged from 0,51 (HDP) to 33,75 µg.ml-1 (THM) for RTgill-W1 and from 0,31 (HDP) to 33,37 µg.ml-1 (THM) for RTG-2. The theoretical LC50 estimation was calculated according to Tanneberger et al. (2013). For all substances, cytochrome P450 1A activity was monitored using 7-ethoxyresorufin-o-deethylase (EROD), four out of five tested chemicals were statistically positive for EROD, the highest EROD response was observed for the most toxic compound - HDP. Only TCS did not show statistically significant cytochrome P450 1A activity. In addition, oxidative stress was measured with the fluorescent dye...
107

Potrebbe l'applicazione di pesticidi influenzare l'abbondanza, la struttura, la biodiversità e la funzionalità della comunità microbica del suolo? / COULD PESTICIDE APPLICATION AFFECT ABUNDANCE, STRUCTURE, BIODIVERSITY AND FUNCTIONALITY OF SOIL MICROBIAL COMMUNITY?

PERTILE, GIORGIA 17 March 2016 (has links)
In agricoltura, i pesticidi sono stati usati molto frequentemente per salvaguardare le colture dagli attacchi di parassiti e dalle malattie. Questi pesticidi, oltre a uccidere gli organismi target, molte volte colpiscono anche gli organismi non-target. Tra gli organismi non-target, possiamo individuare molti microrganismi utili a determinare la fertilità e la qualità del terreno. La presenza di questi xenobiotici nel terreno può influenzare i principali cicli biogeochimici (N, C, S, P) e altre vie metaboliche (es. β-ketoadipate). In questo studio abbiamo analizzato gli effetti di isoproturon, tebuconazole e chlorpyrifos sull’abbondanza, sulla struttura e sulla diversità della comunità microbica. Inoltre, abbiamo anche studiato gli effetti di questi pesticidi sui geni coinvolti nel ciclo dell’azoto. Si è potuto notare che l’abbondanza della comunità batterica è molto influenzata dall’applicazione del fungicida tebuconazole . Per quanto riguarda gli studi sulla funzionalità e diversità della popolazione microbica, l’applicazione di questi pesticidi sembra non indurre una chiara dose-dipendente e un effetto tempo. Diversamente, in relazione all’analisi sulla diversità microbica, possiamo affermare che l’applicazione di questi tre pesticidi ha influenzato il numero di OTU rilevate; tuttavia, l’indice di diversità (H’) ci dice che l’uso di questi pesticidi porta ad un incremento della diversità all’interno dei campioni trattati. In conclusione, è possibile affermare che l’applicazione di questi pesticidi influenza l’abbondanza e la funzionalità della popolazione microbica, ma non induce una diminuzione della diversità all’interno della medesima comunità. / In agriculture, pesticides have been frequently used to protect crops from pest and disease attacks. Many times such pesticides, besides killing the target organisms, hit non-target organisms. Among the non-target organisms, we can find many useful microorganisms that determine fertility and soil quality. The presence of these xenobiotics in soil can influence the main biogeochemical cycles (N, C, S, P) and other metabolic pathways (eg. Β-ketoadipate). In this study, we investigated the effects of isoproturon, tebuconazole and chlorpyrifos on the abundance, the structure and the diversity of the microbial community. We have also studied the effects of these pesticides on the genes involved in the nitrogen cycle. It was observed that the abundance of the bacterial community is significantly affected by the application of the fungicide tebuconazole. As for the studies on the functionality and the diversity of the bacterial population, the application of these pesticides does not seem to induce a clear dose-dependent nor a time effect. On the contrary, with respect to the analysis on microbial diversity, we observed that the application of these three pesticides did influence the number of detected OTU, whereas the diversity index (H') tells us that the use of such pesticides leads to an increase of diversity within the treated samples. Finally, we can conclude that the application of these pesticides affects the abundance and function of the microbial population, but does not lead to lower diversity within the same community.
108

Geoestatística e Ecotoxicologia como ferramentas para gestão de reservatórios / Geostatistics and Ecotoxicology as tools for reservoir ecotoxicology management. Case study of Reservoir Guarapiranga (São Paulo, BR)

Leal, Philipe Riskalla 14 February 2017 (has links)
Neste trabalho, objetivou-se o avaliar ecotoxicidade potencial do sedimento do Reservatório Guarapiranga da cidade de São Paulo (Brasil) frente a contaminação por metais, a fim de discutir sua qualidade e sua atual política de gerenciamento ambiental. Os metais analisados foram: Al, Cd, Cr, Cu, Fe, Mn, Pb e Zn. Utilizou-se das ferramentas de sistema de informação geográfica, geoprocessamento de imagens e da geoestatística para avaliação da dispersão espacial dos metais ao longo do sedimento do Reservatório, considerado por este trabalho como aquela região de maior implicação ecotoxicológica para contaminantes metálicos. Analisaram-se também as variáveis granulometria, matéria orgânica, nitrogênio total, fósforo total e umidade do sedimento, a fim de se estudar quimiometria do sedimento, a fim de melhor compreender as distribuições dos contaminantes ao longo do sedimento. Denominou-se esta classe de variáveis quimiométricas de parâmetros estruturais do sedimento. Observou-se grande variabilidade quantitativa e espacial entre os metais analisados, denotando que o Reservatório Guarapiranga sofre contaminação por diferentes vias no sistema. Observou-se falta de correlação quimiométrica entre os parâmetros estruturais do sedimento com os contaminantes metálicos, denotando grande variabilidade interna desse sistema. Referente a política de manejo do Reservatório, especialmente relativa ao controle algal e cianofítico, observou-se um gerenciamento de grande impacto ecossistêmico, focado mais no custo imediato do que em planejamentos de longo prazo. Tal gerenciamento, hoje, traz risco ecotoxicológico ao reservatório, mas também toxicidade potencial à própria população abastecida pelo reservatório quanto àquela sob exposição direta a este reservatório por meio de recreação, esportes náuticos, ou alimentação / In this work, the metal ecotoxicological potential of an urban reservoir\'s sediment has been assessed, in order to discuss its management policies and its implications to the society and to the ecosystem. The Reservoir Guarapiranga has been selected as the model environment for this study, once it possess a long history since its damming, several studies regarding its water and sediment conditions and an easy accessibility. The metals of greater implication to the Guarapiranga\'s cause were the Al, Cd, Cr, Cu, Fe, Mn, Pb and Zn, being selected as the main parameters for this study. Several scientific areas have been applied in this work. Among them, it is cited the Geographical Information System, geostatistical analysis, imagem geoprocessing, geochemical and chemometric analysis and, finally, the ecotoxicology. In order to better understand the relationship between the sediment and its contaminants, this study also assessed the granulometry, organic matter, total nitrogen, total phosphorous and the umidity of the sediment as explainable variables, translated as chemometric variables. My results showed great variability among the metals analized, denoting that each metal has its own path of contamination (contamination source point) in the reservoir, but a main direction (axis) of dispersion on the sediment. This later, mostly due to hydrological and eolic aspects of the ecosystem. Also, it\'s been observed lack of correlation between the chemometric and the metals parameters of the sediment, which also demonstrated the variation and stochasticity of the ecosystem. Lastly, the reservoir\'s environemntal management policies specially related to the algal and cyanophitic controlhave been analized through an ecotoxicological prisma, and it been denoted that it lacks long-term considerations, focusing only at punctual or short to middle-term solutions,resulting in the terrible ecotoxicological condition observed in the Guarapiranga\'s reservoir. Here, I punctuate the importance of new policy making, and its importance to the ecosystem and to the society, once hazardous condition of a reservoir is unberable not only through a ecosystemperspective, but as a sociological one
109

Phytoremédiation d'un sol contaminé de la Bekaa (Liban) : Valorisation de la biomasse par production d'huiles essentielles à activités biologiques / Phytoremediation of a polluted soil in the Bekaa valley (Lebanon) : Valorization of the biomass by producing essential oil with biological activities

El Alam, Imad 30 January 2018 (has links)
Situé au sein de la plaine de la Bekaa au Liban, le fleuve du Litani est sujet à divers rejets agricoles, industriels, domestiques et urbain. Lors de l'irrigation des parcelles agricoles, les eaux du fleuve contaminent le sol et les cultures présentant ainsi un risque pour la santé de l'Homme et l’environnement. Parmi les méthodes de remédiation émergentes et en adéquation avec le développement durable figure la phytoremédiation assistée par les champignons mycorhiziens arbusculaires (CMA). Cependant, la rentabilité de ce mode de gestion constitue l'un des principaux freins à son développement et la valorisation de produits biosourcés, à hautes valeurs ajoutées, issus de la biomasse végétale produite sur ces sols contaminés permettrait d'abaisser les coûts globaux de gestion et de requalification de ces sols pollués. Parmi les filières de valorisation éco-innovantes, la culture de plantes à parfums aromatiques et médicinales (PPAM) productrices d'huiles essentielles (HE) à activités biologiques peut être suggérée comme une option prometteuse. Ainsi, l'objectif de ce travail de thèse a consisté tout d'abord à caractériser le sol d'une parcelle expérimentale située à Marj-Bekaa et directement irriguée par les eaux du Litani, puis à proposer un mode de gestion basé sur la production d'HE pouvant ainsi répondre aux attentes environnementales, économiques et sociales. Nos résultats montrent que la parcelle expérimentale, située à Marj-Bekaa et directement irriguée par les eaux du Litani, est principalement contaminée par des éléments traces métalliques [Ni (88 mg.Kgˉ ¹), Cr (122 mg.Kgˉ ¹), V (170 mg.Kgˉ ¹) et Mn (551 mg.Kgˉ ¹) et des polluants organiques [les alcanes (2.5 g.Kgˉ ¹ du sol)]. Cette contamination est à l'origine d'une (1) cytotoxicité vis-à-vis des cellules pulmonaires et hépatiques mise en évidence grâce au dosage de deux activités enzymatiques, la lactate déshydorgénase et la déshydorgénase mithochondriale mais aussi d'une (2) écotoxicité révélée par la réduction (i) des taux de germination des graines (blé, trèfle, luzerne, ray-grass et fétuque), (ii) de la biomasse microbienne du sol [bactéries Gram-positive et Gram-négative, champignons mychoriziens à arbuscules (CMA), champignons saprotrophes et ectomycorhiziens], (iii) de l'abondance et de la diversité des spores de CMA et (iv) de la richesse et de la diversité végétales. Cependant, toutes les plantes indigènes étaient mycorhizées. C'est pourquoi, la faisabilité de la phytoremédiation assistée par les CMA du site expérimental de la Bekaa, a été testée à la fois en microcosmes et in situ en utilisant une plante aromatique productrice d'HE, l'origan (Origanum syriacum L.). Nos résultats ont montré que non seulement l'origan possède un potentiel de dissipation des alcanes mais en plus cette plante ne transfère pas ces polluants dans les HE extraites à partir de sa biomasse aérienne. Par ailleurs, il a été constaté que la mycorhization a une influence sur la composition des HE. En outre, notre étude a permis l'évaluation de diverses activités biologiques (antifongiques, antioxydante et anti-inflammatoire) d'une gamme d'HE extraites de différentes espèces végétales dont l'origan et ce en présence et en absence des cyclodextrines (HP-β-CD), oligosaccharides cycliques qui complexent les HE et augmentent leurs biodisponibilités. / Located in the Bekaa valley in Lebanon, The Litani River is exposed to agricultural, industrial, domestic and urban wastewaters. Through the irrigation of agricultural soils, the river's water contributes to soil and culture contamination and represents a risk for human health and environment. Amongst the emergent sustainable remediation methods, there is arbuscular mycorrhizal fungi (AMF) assisted-phytoremediation. However, one of the limitation in using phytoremediation as depollution method is its socio-economic profitability. Among the eco-innovative valorization processes with high profitability, the cultivation of aromatic and medicinal plants producing essential oils (EO) with biological activities has been suggested as a promising option. Thus, this thesis work aims firstly at characterizing the soil of an experimental site located at Marj-Bekaa and directly irrigated by the Litani's water and secondly at proposing a mode of management of the contaminated soil based on the production of EO that can meet environmental, economic and social expectations. Our findings showed that the soil sampled in Marj-Bekaa is mainly contamined by metal trace elements [Ni (88 mg.Kgˉ ¹), Cr (122 mg.Kgˉ ¹), V (170 mg.Kgˉ ¹) and Mn (551 mg.Kgˉ ¹) and alkanes (2.5 g.Kgˉ ¹ of soil). This contamination is causing (i) cytotoxicity against both bronchial and hepatic human cells revealed by the evaluation of two enzyme activities, extracellular lactate dehydrogenase and mitochondrial dehydrogenase, as well as (2) ecotoxicity pointed out by the reduction of (i) seed germination (wheat, clover, alfalfa, ryegrass and tall fescue), (ii) soil microbial biomass [Gram-positive and Gram-negative bacteria, arbuscular mycorrhizal fungal (AMF), ectomycorrhizal and saprotrophic fungi], (iii) abundance and diversity of AMF spores as well as (iv) the plant diversity and richness. The AMF-assisted phytoremediation of the Bekaa experimental site was evaluated both in microcosms and in situ experiments using an aromatic plant producing EO, oregano (Origanum syriacum L.). Our results revealed that oregano plant possess an alkane's dissipation potential and no polluant transfer is detected in EO. Moreover, the mycorrhization modified the EO composition. On the over hand, our study evaluated several biological (antifungal, antioxidant and anti-inflammatory) activities of a range of EO extracted from many plant species including oregano, in the presence and the absence of cyclodextrines (HP-β-CD), cyclic oligosaccharides that encapsulate EO and enhance their bioavailabilities.
110

Sistema de análises em fluxo empregando multicomutação para avaliação de toxicidade aguda com Vibrio fischeri / A multicommuted flow-based system for acute toxicity evaluation with Vibrio fischeri

Adame, Andressa 25 April 2014 (has links)
Um sistema de análises em fluxo com multicomutação foi desenvolvido para a mecanização do bioensaio de toxicidade aguda com a bactéria Vibrio fischeri, o qual é baseado na diminuição da luminescência bacteriana causada por espécies tóxicas.Microbombas solenoide foram utilizadas para melhorar as condições de mistura, permitindo também que diluições fossem realizadas em linha com a alteração do volume de amostra e a sobreposição parcial entre a zona da amostra e a suspensão bacteriana. Uma cela de fluxo em espiral, posicionada na janela de emissão de um espectrofluorímetro, foi empregada para as medidas de luminescência e um banho de água construído em laboratório, baseado no efeito Peltier, foi utilizado para manter a temperatura do bioensaio em (13,0±0,1) °C. Um pequeno volume da suspensão bacteriana (120 ?L) foi selecionado visando minimizar o consumo e, consequentemente, os custos do ensaio. O tempo de contato entre a suspensão bacteriana e a amostra foi reduzido para 5 min para aumentar a frequência de amostragem e evitar a atenuação da luminescência devido ao tempo de vida curto das bactérias. Os valores de CE50 para os controles positivos foram estimados em 2,5 ± 0,7, 2,0 ± 0,5 e 10 ± 4 mg L-1 para o Zn(II), Cu(II), e Cr(VI), respectivamente, sendo concordantes com os valores da literatura. Os valores de CE50 para alguns poluentes emergentes (parabenos, cafeína, acetaminofeno, diclofenaco e ácido salicílico) concordaram com os obtidos utilizando o kit comercial BioTox(TM), realizado em micro placa, a nível de confiança de 95 %. Os coeficientes de variação foram estimados em 2,4 e 2 % (n = 10), na ausência e na presença de 0,6 mg L-1 de Zn(II), respectivamente. O sistema de análises em fluxo proposto é, então, uma alternativa simples, rápida, robusta e precisa para a determinação da toxicidade aguda utilizando pequenos volumes de amostra e suspensão bacteriana. Além disso, o sistema apresenta vantagens em comparação com os bioensaios em batelada e em fluxo, tais como ajuste de salinidade e diluições das amostras em linha e a determinação da cinética de toxicidade das espécies químicas / A multicommuted flow system was developed for automation of the acute toxicity bioassay using Vibrio fischeri bacteria, which exploits the decrease of the bacterial luminescence caused by toxic species. Solenoid micro-pumps were employed to improve mixing conditions and to perform on-line dilutions of the tested compounds by changing the sample volume and exploiting the partial overlap between sample zone and the bacterial suspension. A spiral flow cell, placed at the emission window of a spectrofluorimeter, was employed for signal measurement and a lab-made water bath based on the Peltier effect was used for maintain the temperature of the bioassay at (13.0±0.1) oC. A low volume of the bacterial suspension (120 ?L) was selected in order to minimize its consumption and, consequently, the costs of the assay. The contact time between bacterial suspension and sample was reduced to 5 min to increase the sampling rate and to avoid luminescence fading due to the bacteria short lifetime. EC50 values for positive controls were estimated as 2.5 ± 0.7, 2.0 ± 0.5 and 10 ± 4 for Zn(II), Cu(II), and Cr(VI), respectively, being in agreement with literature values. The EC50 values for some emerging pollutants (parabens, caffeine, acetaminophen, diclofenac and salicylic acid) agreed with those obtained from commercial BioTox(TM) kit performed in micro plate at the 95% confidence level. The coefficients of variation were estimated as 2.4 and 2 % (n=10), in the absence and presence of 0.6 mg L-1 Zn(II), respectively. The proposed flow system is then a simple, fast, robust and accurate alternative for acute toxicity determination, using low sample and bacterial suspension volumes. Furthermore, the system presents advantages in comparison to batch and previous flow-based bioassays, such as the achievement of in-line salinity adjustment and sample dilutions, and the determination of toxicity kinetic for every assayed chemical species

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