321 resultados para toxicidade de metais pesados
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Diuron (3-(3,4-Dichlorophenyl)-1,1-dimethylurea) is a substituted urea herbicide widely used on agricultural crops such as soy, cotton and sugar cane. In a previous long-term study this herbicide exerted carcinogenic activity on the urinary bladder and renal pelvis mucosa of Wistar rats and breast of mice. Also, it was shown to be carcinogenic to the mice skin in a initiation-promotion assay. In 1997, the northamerican EPA evaluated Diuron as a “known/likely” carcinogen for humans (USEPA, 2004). In a previous study developed at this laboratory, male Wistar rats treated with Diuron 2500 ppm during 20 weeks presented increased indices of cell proliferation and incidences of simple urothelial hyperplasia (HS) in the urinary bladder. Under scanning electron microscopy (SEM) severe urothelial necrosis and hyperplasia were observed. However, in that study the urinary bladders of animals exposed to lower doses of Diuron were not examined under SEM. Therefore, the possible dose-response influence of Diuron on the urothelium under SEM is not known. The present study aimed to analyze under SEM the urinary bladder of male Wistar rats exposed to 125 ppm, 500 ppm and 2500 ppm doses of Diuron through diet during 20 weeks and to compare to the previous histological findings in the same material. Under SEM, 125 ppm and 2500 ppm groups presented significantly (p<0,05) increased incidences of simple hyperplasia, i.e., 7/10 and 8/10 respectively, compared to control group and the 500 ppm group The sensitivity of SEM was higher since it detected a 45% incidence of hyperplasiaswhile the histological analysis found only 27%. Considering SEM as the gold-standard, histology showed a 44% sensitivity, 86.4% specificity, a positive predictive value of 72,7% and negative predictive value of 65,5% and accuracy of 67,5%. Scanning Electron Microscopy...(Complete abstract click electronic access below)
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In order to enable the reuse of the large surplus volume of petroleum produced water for irrigation of crops inedible, the quality evaluation of this water is very important. This work aimed to evaluate the effectiveness of the diffusive gradient in thin films technique (DGT) for the determination of labile Cu (II), Mn (II) and Zn (II) in petroleum produced water destined to reuse in agriculture. Samples were collected at the exit of the wastewater treatment plant (WWTP) (after separation oil/water and flotation) of a Petrobrás onshore production region. Basically, the laboratory experiments with DGT devices involved the evaluation of the behavior of the main variables of the technique for determination of analytes in the samples (diffusion coefficients, immersion time, fractionation of organic and inorganic species, and performance of diffusion gels with different porosities, among others). Also, experiments were conducted based on the solid phase extraction (SPE) protocol with Chelex- 100 resin using previously established protocols to support the study. During the project the possibility of in situ immersions in water treatment plants was evaluated. The DGT technique presented satisfactory results for determination of Mn in produced water, and can be used for in situ determinations. However, the results obtained for Cu and Zn show the need of additional studies
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Petroleum and its subproducts are considered a treat for the environmental quality because of the many environmental accidents that may occur during exploitation, transport and storage. A common remediation technique used in the contaminated areas is based on the use of surfactants, mainly the chemical ones, because they have low production costs. In the other hand, some microorganisms have indicate capacities of producing surfactants that emulsify substances and as result, offer a bigger contact surface for the microbiota degradation. This biossurfactants stand out in comparison with the chemical surfactants because they present lower micelar concentration values, are more tolerant for temperature and pH variation, because they are biodegradable, have low toxicity, higher emulsification and hydrocarbon solubilization index. In this way, after the surfactant application, a toxicity evaluation have to be made to identify the treatment effects. In soil, the activity of some microbial enzymes can show the environmental behavior of the contaminant under different treatment conditions. Dehydrogenase is one example of those enzymes that can demonstrate indirectly the effect of the pollutant on the soil microorganisms. The aim of this paper was to evaluate the toxicity after the addition of a surfactant and/or Pseudomonas aeruginosa LBI in soil contaminated by a mineral automotive lubricant. The previous mentioned bacteria are a potential biossurfactant (rhamnolipid) producer. In order to evaluate the toxicity, the dehydrogenase test was run. In this test, trifeniltetrazolium compound (TTC) after utilized as an electron acceptor, turns into trifenil formazan (TPF), that can be indirectly quantified using the absorbance measured by the spectrophotometer UV-visible. In this way, it was possible to quantify the dehydrogenase activity from the contaminated soil samples... (Complete abstract click electronic access below)
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The continuous advance of the Brazilian economy and increased competition in the heavy equipment market, increasingly point to the need for accurate sales forecasting processes, which allow an optimized strategic planning and therefore better overall results. In this manner, we found that the sales forecasting process deserves to be studied and understood, since it has a key role in corporate strategic planning. Accurate forecasting methods enable direction of companies to circumvent the management difficulties and the variations of finished goods inventory, which make companies more competitive. By analyzing the stages of the sales forecasting it was possible to observe that this process is methodical, bureaucratic and demands a lot of training for their managers and professionals. In this paper we applied the modeling method and the selecting process which has been done for Armstrong to select the most appropriate technique for two products of a heavy equipment industry and it has been through this method that the triple exponential smoothing technique has been chosen for both products. The results obtained by prediction with the triple exponential smoothing technique were better than forecasts prepared by the industry experts
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Diplópodos são animais detritívoros sendo considerados importantes macro-artrópodos do solo, desempenhando importante papel na manutenção do equilíbrio do ecossistema. Comumente não apresentam população numerosa, mas desequilíbrios ambientais, mudanças climáticas e utilização de pesticidas podem eliminar possíveis competidores ocasionando explosões populacionais. Dotados de um corpo cilíndrico com 25 a 100 segmentos com cutícula; o exoesqueleto da maioria dos diplópodos é fortemente calcificado. Possuem diplossegmentos que se originam da fusão entre dois segmentos durante o desenvolvimento e a grande parte destes diplossegmentos apresenta dois pares de pernas, de onde deriva o nome Diplopoda. O tubo digestório destes animais é formado por três regiões: o intestino anterior, o médio e o posterior. Trabalhos com morfologia do tubo digestório de milípides são raros e na maioria antigos. Assim, este trabalho de conclusão de curso objetivou realizar uma revisão bibliográfica sobre as descrições morfológicas existentes sobre o tubo digestório de diplópodos visando rever a nomenclatura utilizada para os diferentes componentes presentes nas regiões que o compõem, principalmente para o tecido presente na região do intestino médio denominada até então de camada de “corpo gorduroso” constituinte do intestino médio. Foi intuito também, rever a utilização do tubo digestório de diplópodos como biomarcador em bioensaios de solos impactados. Após a revisão dos dados na literatura, ficou claro que a camada presente no intestino médio de diplópodos, denominada de “corpo gorduroso”, na realidade é constituída por células hepáticas, as quais foram descritas na literatura como sendo de distribuição aleatória, sem formar uma camada contínua
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A concentração de dióxido de carbono (CO2) global eleva-se a cada ano, isso deve-se a um desequilíbrio entre as taxas de emissão deste gás por atividades antropogênicas e fontes naturais e a taxa que a biosfera e oceanos o removem da atmosfera. O CO2 é um importante constituinte químico do ambiente, pois este é um gás que aprisiona radiação infravermelha emitida pela superfície da Terra, contribuindo, assim, para a manutenção da temperatura global necessária a vida. As alterações na concentração de CO2 na atmosfera afetam inúmeros animais que dependem que estas estejam altamente controladas para poderem sobreviver. Em abelhas Apis mellifera valores elevados de temperatura ou níveis de CO2 dentro da colméia podem ter efeitos deletérios. Estes insetos são considerados bioindicadores naturais, pois apresentam diferenças fisiológicas conforme as condições do ambiente, sendo utilizadas na avaliação de efeitos a várias substâncias presentes no meio. Atualmente uma das técnicas utilizadas para a avaliação do efeito de estímulos externos é a utilização da marcação da proteína c-Fos através da expressão do gene c-fos, que indicam tanto a existência de atividade celular como também possibilita a identificação de áreas cerebrais determinadas. Esta proteína foi utilizada com o intuído de verificar se concentrações elevadas de gás carbônico são capazes de alterar as funções cerebrais da abelha Apis mellifera, comprometendo sua atividade de orientação e, conseqüentemente seu forrageamento. Marcações positivas à proteína Fos foram observadas nas regiões dos lobos ópticos e ocelos tanto do grupo controle quanto dos grupos Resumo Jacob, C. R. O. 9 expostos ao gás dióxido de carbono para todas as idades coletadas, estes resultados estão relacionados com a...(Resumo completo, clicar acesso eletrônico abaixo)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Ensuring availability of quality water for human consumption causes becomes an increasing number of studies for the analysis of effluent before and after treatment, so that its release into receiving bodies do not cause significant changes in the river water and on the biological communities related to them. The biomarkers of toxicity have long been used to verify the potential toxic effluent and its correlation with the treatment efficiency of them. In this context, the cladoceran Ceriodaphnia dubia stands out because it is a benthic aquatic organism highly sensitive to environmental changes. In this study, to evaluate the interference of the release of treated wastewater of oil refinery in Rio Atibaia, we sought to determine the toxicity on population dynamics of Ceriodaphnia dubia microcrustacean in water samples upstream and downstream from the launch site, compared with samples from Rio Jaguarí at the point of capture by the company itself and treated effluent. We have studied the number of offspring produced in 10 replicates, each starting with a test individual of up to 24 hours for each sample and correlated the results with physical-chemical and microbiological tests performed by a laboratory technician. For most tests, the results indicate that the treated effluent gives sub-lethal toxicity to the microcrustacean, as delay the onset of the reproductive cycle of the same
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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The objective of this work is to use the technique of diffusion by concentration gradient films (DGT) for evaluation of dissolved urano in hydro bodies. For this we chose this work as a systems investigation of water bodies in the region of Poços de Caldas, state of Minas Gerais, because, there is a large amount of mining of uranila. The technique to be used to evaluate the potential for dissolved metals analysis involves the use of passive samplers with application in in situ. This allows detection with excellent sensitivity and selectivity allowing the determination of the labile fraction of dissolved metals
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Aquatic ecosystems are suffering many impacts caused by human activities resulting from the activities occurring around them. With technological progress observed in recent years, this environment has received large amounts of chemicals from industries, agriculture and urban area that affect the aquatic biota. Among these sources of contamination, the oil industry has contributed to the pollution of aquatic environments with both effluents as produced water well as oil spills and their derivatives having toxicity to various organisms. With all the environmental issues has increased concern about water quality and has been used ecotoxicological tests with aquatic organisms to ecosystems to assess the toxicity of chemicals present in the water. In this context the microcrustacea Daphnia similis stands out as a freshwater organism very representative of the aquatic fauna of rivers and high sensitivity to environmental impacts. Thus, the present study aimed to evaluate the lethal toxicity of crude oil and produced water on this microcrustacea. The results showed that the microcrustacea presented high sensitivity to contaminants primarily crude oil. There was also the influence of environmental variables pH and temperature on the survival of organisms
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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