Rozprawy doktorskie na temat „Hydrocarbon accumulation”
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Casenave, Viviane. "Architecture et dynamique des migrations d'hydrocarbures dans une couverture sédimentaire à hydrates de gaz : implications sur le système pétrolier (bassin du Bas Congo)". Thesis, Montpellier, 2017. http://www.theses.fr/2017MONTT143/document.
Pełny tekst źródłaEvidence of fluid flow features and their mechanisms of migration through the sedimentary pile are a known phenomenon on continental margins. It has been widely studied over the past twenty years, notably due to the improved resolution of seismic data and the abundance of data in these areas due to oil and gas exploration.The Lower Congo basin, offshore West Africa, is a prolific petroleum province that has been extensively studied, and has been in operation for over 30 years. The area of interest is located above a producing oil field (the Moho license), in which hydrocarbons are trapped in turbidite channels. The work is primarily based on the analysis of geophysical data including 3D and 2D-THR seismic, multibeam bathymetry and corresponding backscatter, as well as background data (samples taken from ROV photos, geochemical analyses).The analysis of this important seismic dataset revealed abundant evidence of fluid migration in the Mio-Pliocene sedimentary pile. They mainly correspond to indications of vertically focused migration, including current fluid expulsion structures on the seafloor, and buried structures, interpreted as fossile and indicating former activity of the fluid expulsion system. The studied fluid migration features mainly consist of pockmarks (depressions) and carbonate cementations. These two types of indicators can build vertical stacks, over several hundred meters, highlighting the durability of the fluid escapes and suggesting the development of real pipes.A new type of pockmarks has been discovered, the spider structures, which are located above a turbiditic reservoir, and which result from a focused migration of thermogenic hydrocarbons. They are related to gas hydrates, in the context of a sloping BSR (Bottom Simulating Reflector), due to the presence of the hydrate wedge. A dynamic model of their functioning is proposed, showing that these structures develop upslope, due to the gas migration under the sloping BSR. A study of the BSR, in the particular context of the hydrates wedge, allows to propose a model of gas escapes, linked to the dissociation of the hydrates, during a sea level fall. This model presents a dissociation of gas hydrates of regional scale (associated with biogenic gas), localized at the gas hydrate wedge zone of the last lowstand. Finally, the network of fluid escape structures of the Mio-Pliocene interval was investigated in order to understand its architecture and the mechanisms of fluid migration in the study area. Hydrocarbons appear to migrate mainly along certain portions of faults and vertically crosscutting the sedimentary pile through pipes or chimneys. The base of the Pliocene, associated with a sea level fall, marks the formation of the first paleo-spiders, as well as a level containing numerous evidence of gas. A model of this network of fluid migrations is proposed, integrating the indicators of hydrocarbon migrations through the sedimentary pile, and the major event of the Pliocene base. This study seems to indicate that a the sea level fall constitute a trigger for the fluids migrations, in the basin.This work thus marks the starting point of a larger-scale investigation which consists in, on the one hand, searching for similar structures (spiders and bands of pockmarks) in other basins ; and, on the other hand, by comparing fluid flow events with the eustatic curve
Dylewski, Mary. "Subsurface analysis of the 'Trenton' Limestone, north-central Ohio, and its relationship to hydrocarbon migration and accumulation". Connect to resource, 1985. http://rave.ohiolink.edu/etdc/view.cgi?acc%5Fnum=osu1265287066.
Pełny tekst źródłaMileo, Paulo Graziane MendonÃa. "UtilizaÃÃo da simulaÃÃo molecular na prediÃÃo da acumulaÃÃo de alcanos em estruturas metalorgÃnicas". Universidade Federal do CearÃ, 2014. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=11829.
Pełny tekst źródłaO gÃs natural, cuja maior parte à constituÃda de metano, à um combustÃvel que vem se expandindo no mercado energÃtico global por possuir uma queima mais limpa que outros derivados petrolÃferos e por ser mais eficiente energeticamente. No entanto, ele possui como grande desvantagem frente a outros combustÃveis a dificuldade em ser armazenado devido a sua baixa densidade. Materiais microporosos vÃm sendo utilizados para aumentar tal densidade por meio da adsorÃÃo. No entanto, um dos problemas encontrados na utilizaÃÃo desses materiais se trata da diminuiÃÃo da capacidade adsortiva apÃs ciclos de carga e descarga de tanques de armazenamento. O estudo desse problema, porÃm, demanda um grande nÃmero de experimentos e uma aparelhagem relativamente sofisticada. Este trabalho propÃs a simulaÃÃo molecular como uma metodologia vÃlida a ser utilizada para o estudo da retenÃÃo de alcanos em carbono ativado e em oito estruturas metalorgÃnicas: IRMOF-1, ZIF-8, CuBTC, PCN-11, PCN-14, UiO-66, MIL-100 e MIL-101. Considerou-se o gÃs natural como uma mistura de metano (C1), etano (C2), propano (C3) e butano (C4) nas proporÃÃes de, respectivamente, 84,7:10:0,9:0,1. Para a validaÃÃo dos modelos utilizados nassimulaÃÃes, as isotermas simuladas de C1, C2, C3 e C4 foram ajustadas Ãs experimentais obtidas da literatura para cada um dos materiais. Foram entÃo realizadas isotermas multicomponentes e estudo de sÃtios de adsorÃÃo para o estudo da retenÃÃo de hidrocarbonetos e da influÃncia de fatores composicionais e estruturais nesse fenÃmeno. Observou-se que as MOFs MIL-100 e ZIF-8 sÃo as mais recomendadas para uso em tanques de GNA por critÃrios de capacidade, eficiÃncia adsortiva e estabilidade. Verificou-se ainda que MOFs que apresentam sÃtios de adsorÃÃo pouco dispersos apresentam uma maior tendÃncia à acumulaÃÃo de hidrocarbonetos.
Natural gas, which consists mostly of methane, is a fuel that has been expanding in the global energy market by having a cleaner burning than other petroleum derivatives and are more energy efficient. However, it has a great disadvantage compared to other fuels: it is difficult to be stored due to its low energy density. Microporous materials have been used to increase the energy density by adsorption. However, one of the problems encountered in using these materials it comes to the decrease in adsorption capacity after charge and discharge cycles of the storage tanks. The study of this problem, however, requires a large number of experiments and a relatively sophisticated equipment. This paper proposes themolecular simulation as a valid methodology to study the retention of alkanes in activated carbon, and eight metalorganic structures: IRMOF - 1, ZIF - 8, CuBTC, PCN- 11, PCN -14, UiO -66, MIL -100 and MIL- 101. We considered the natural gas as a mixture of methane (C1), ethane (C2), propane (C3) and butane (C4) in the proportions respectively 84,7:10:0,9:0,1. For the validation of the models used in the simulations, the simulated isotherms of C1, C2, C3 and C4 were adjusted to fit the experimental ones, obtained from the literature data for every material. Multicomponent isotherms were then performed, the retention of hydrocarbons were studied as well as the influence of compositional and structural factors to this phenomenon. We noticed that the MOFs MIL-100 and ZIF-8 are the most recommended to use in GNA tanks according to the criteria of capacity, adsorption efficiency and stability. We verified as well that MOFs that have adsorption sites too localized present a larger tendency to the accumulation of hydrocarbons.
Schellaars, Samantha. "The effect of hydrocarbon accumulation upon seismic response within the Barrow Sub-basin, North West Shelf of Australia : a model-based study /". Adelaide, 1993. http://web4.library.adelaide.edu.au/theses/09SB/09sbs322.pdf.
Pełny tekst źródłaSiuta, Chase Michael. "Measuring Material Properties of Proton Exchange Membranes using Pressure Loaded Blister Testing and Digital Image Correlation". Thesis, Virginia Tech, 2011. http://hdl.handle.net/10919/76858.
Pełny tekst źródłaMaster of Science
Amalfi, Frederick A., i Milton R. Sommerfeld. "Accumulation of Heavy Metals and Petroleum Hydrocarbons in Urban Lakes: Preliminary Results". Arizona-Nevada Academy of Science, 1988. http://hdl.handle.net/10150/296412.
Pełny tekst źródłaA preliminary survey of several urban lakes in the Phoenix metropolitan area was undertaken to assess the degree of accumulation of priority pollutant metals and petroleum -based hydrocarbons in these impoundments. Three sediment samples were collected from each lake along a transect (from a probable point of stormwater addition to the opposite shore), and were composited on an equal weight basis prior to analysis. Total petroleum hydrocarbon concentrations ranged from 30 to 8000 mg /kg dry weight. The concentration ranges (mg /kg dry weight) of total metals were: arsenic 7-26, copper 25-2800, chromium 14-55, nickel 5-40, lead < 1-138, selenium < 0.5-1.1, and zinc 33-239. Silver and cadmium were undetectable (< 5.0 and < 0.5 mg /kg, respectively). Factors that may be associated with the magnitude of accumulation in urban lakes include lake age, primary source of influent, reception of stormwater runoff, mechanical aeration of the water, and direct chemical addition.
Kloss, Olaf. "The relationship of faulting to hydrocarbon accumulations in the Barrow and Exmouth Sub-basins /". Title page, abstract and table of contents only, 1996. http://web4.library.adelaide.edu.au/theses/09S.B/09s.bk66.pdf.
Pełny tekst źródłaSchindler, Kimberly J. "THE LINKS BETWEEN GULF OF MEXICO SEAFLOOR CHARACTERISTICS AND PETROLEUM HYDROCARBONS FOLLOWING THE DEEPWATER HORIZON OIL SPILL". UKnowledge, 2019. https://uknowledge.uky.edu/ees_etds/78.
Pełny tekst źródłaHandy, Andrea Renee. "Acute Toxicity and Immunotoxicity Testing of Total Petroleum Hydrocarbons in Aquatic and Terrestrial Organisms". Wright State University / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=wright1185910580.
Pełny tekst źródłaLundstedt, Staffan. "Analysis of PAHs and their transformations products in contaminated soil and remedial processes". Doctoral thesis, Umeå universitet, Kemi, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-57.
Pełny tekst źródłaAbraham, Klaus. "Exposition gegenüber Dioxinen und verwandten Substanzen". Doctoral thesis, Humboldt-Universität zu Berlin, Medizinische Fakultät - Universitätsklinikum Charité, 2003. http://dx.doi.org/10.18452/13855.
Pełny tekst źródłaThe accumulation of lipophilic and biologically persistent chlorinated hydrocarbons in the food chain and the following relatively high exposure of breast-fed infants has caused concern about possible negative health effects in these children. One focus of the document is the question whether the contamination of human milk with polychlorinated dibenzo-p-dioxins (PCDDs, 'dioxins'), dibenzofurans (PCDFs, 'furans') and biphenyls (PCBs) in Germany leads to measurable changes of sensitive biological parameters. Blood was taken from breast-fed (for at least four months, n=80) and formula-fed infants (n=21) at the age of 11 months for extensive investigations regarding the immune system and biological parameters in plasma including those of the thyroid function. From direct measurements of PCDDs, PCDFs and PCBs in plasma of the children and their mothers, the expected accumulation of the compounds was confirmed, corresponding to about 4-times higher values in the infant (compared to maternal values) following a long duration of breast-feeding of 40 weeks. For the different biological parameters investigated, no significant correlation with concentrations of the xenobiotics was found. Therefore, biological effects of these unwanted compounds in human milk. could not be detected, and the existing recommendation for breast-feeding was emphasized. The second focus of the document is the investigation of biological changes in two women exposed to the most toxic dioxin: 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). These women had the highest concentrations of this compound ever measured in adults, one of them suffering from severe chloracne. A broad panel of immunological parameters was measured as well as hepatic cytochrome P450 1A2 (CYP1A2) activity using the caffeine test. For comparison, two age-matched control groups of 30 non-smokers and 20 heavy smokers were studied using the same methods. Results of caffeine tests showed an about 10-fold increase of CYP1A2 activity in the highly TCDD-exposed women, whereas tobacco smoke (28 cigarettes per day on average) was found to increase the activity 1.8-times maximally. Immunological investigations did not reveal a strong impact of TCDD in these highly exposed women. These results confirm that humans are relatively insensitive to the toxic effects of dioxins.
Boucher, Rodney. "Influence of deep-seated structure on hydrocarbon accumulations in the Cooper and Eromanga Basins". 2005. http://arrow.unisa.edu.au:8081/1959.8/46687.
Pełny tekst źródłaBaghdasarian, Siyouneh. "Effect of aryl-hydrocarbon receptor activity on lipid accumulation, insulin content and secretion from clonal pancreatic beta-cells". Thesis, 2018. https://hdl.handle.net/2144/30909.
Pełny tekst źródłaFujii, Tetsuya. "Using 2D and 3D basin modelling and seismic seepage indicators to investigate controls on hydrocarbon migration and accumulation in the Vulcan Sub-basin, Timor Sea, North-western Australia". 2007. http://hdl.handle.net/2440/40062.
Pełny tekst źródłahttp://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1277632
Thesis(M.Sc.)-- Australian School of Petroleum, 2007.
Okedeyi, Olumuyiwa Olakunle. "Assessment of polycyclic aromatic hydrocarbon (PAHs) and heavy metals in the vicinity of coal power plants in South Africa". Thesis, 2012. http://hdl.handle.net/10500/12001.
Pełny tekst źródłaChemistry
D. Phil. (Chemistry)
Ko, Ting-Hwa, i 柯廷華. "Degradation and accumulation of polycyclic aromatic hydrocarbons in marine phytoplankton". Thesis, 2012. http://ndltd.ncl.edu.tw/handle/4dmyjg.
Pełny tekst źródła國立東華大學
海洋生物多樣性及演化研究所
100
In this study, high ( 1×106 cells/ml、1×105 cells/ml ) and low ( 1×104 cells/ml ) concentrations of varies sample sizes and species of marine algae groups are used to compare the degradation and accumulation of 7 different polycyclic aromatic hydrocarbons (PAHs). In Taiwan, Nanno chloropsisoculata and Tetraselmis chui are common marine algal. Within 7 days, N. oculata and T. chui are capable of degrading 4-6 ringed PAHs by 20.5% and 36.7% while accumulation of PAHs by 55.0% and 48.7% respectively. 3 ringed PAHs are difficult for algae to degrade and accumulate; N. oculata and T. chui accumulate PAHs at 10.0% and 7.0% and degraded PAHs at 4.6% and 16.2% respectively. For section of PAHs ( Benzo[b]- fluoranthene、Benzo[k]fluoranthene、Indeno[1,2,3-c,d]pyrene、Benzo[g,h,i]- perylene ) had higher degradation percentage in high numbers algal. In the distribution, algae-water coefficient log Kd has a good linear relationship between log Kow (octanol-water coefficient), and high number algal reduce the equilibrium time. This indicates that PAHs’ distribution in algae and water is a result of their physio-chemical properties. Present study suggests that algae can degrade 4-6 ringed PAHs effectively, but it may also be a result of accumulation of PAHs in the organism.
Li, Yan-Yi, i 李晏毅. "Distribution and accumulation of polycyclic aromatic hydrocarbons in the sediments of Kaohsiung Harbor". Thesis, 2007. http://ndltd.ncl.edu.tw/handle/28448250864439412065.
Pełny tekst źródła國立高雄海洋科技大學
海洋環境工程研究所
95
Twenty surface sediment samples were collected seasonally from Kaohsiung Harbor, Taiwan from March to October 2005. Concentrations of 17 priority polycyclic aromatic hydrocarbons (PAHs) were monitored by gas chromatography equipped with a mass spectrometry detector (GC/MSD). Total concentrations of the PAHs ranged from 517 to 7,389 μg kg-1 dry weight. Sediment samples with the highest PAH concentrations occurred at the area located near to the industrial parks. Municipal sewage also contributed to the PAH contamination in the sediments. According to the observed molecular indices, PAHs contamination in Kaohsiung Harbor generally originated from the high-temperature pyrolytic processes. According to the numerical effect-based sediment quality guidelines (SQGs) of the United States, the levels of PAHs at most studied sites in the Kaohsiung Harbor would not exert adverse biological effects.
Lee, Shu-Ying, i 李叔螢. "Sorption and accumulation kinetics of polycyclic aromatic hydrocarbons in marine rotifer (Brachionus sp.)". Thesis, 2013. http://ndltd.ncl.edu.tw/handle/07084653673004149097.
Pełny tekst źródła國立東華大學
海洋生物多樣性及演化研究所
101
Planktonic organisms play an important role in driving the fate of persistent organic pollutants (POPs) in the marine environment. As a first step in the aquatic food web, plankton is a key to bring POPs from the aquatic environment into the food web. The objectives of this study are (i) to investigate the bioaccumulation of polycyclic aromatic hydrocabons (PAHs) in rotifer (Briachionus sp.), (ii) to compare the sorption and accumulation kinetics of PAHs in rotifer by diffusive uptake, feeding on phytoplankton, and both, and (iii) to discuss the relationship between bioconcentration factor (BCF),bioaccumulation factor (BAF), and octanol-water partition coeffient (Kow).This study includes three experiments. First, use gas-purging system to maintain constant dissolved PAH levels in the reactor and carry on sorption experiment. Second, feed rotifer on contaminated Nannochlorpsis oculata (as the ingestion experiment). Third, we maintain constant dissolved PAH levels in the reactor and feed rotifer on contaminated Nannochlorpsis oculata for the mixing experiment. For each experiment, we sampled every 24 hours to analysis PAHs concentration and biology condition for 120 hours. This study shows that the adsorption of four PAHs on rotifer approaches to saturation after 72 hours. Furthermore, there is no obvious biomagnification in transfer from phytoplankton to rotifer. Lastly, the passive uptake instead of active ingestion dominates the accumulation of PAHs in rotifer. Distribution of BCF and BAF of PAHs are correlated with their hydrophobicities ( Kow values). The knowledge of the PAHs accumulation in rotifer through sorption and ingestion opens a door to future understanding of the biogeochemical exchanges of PAHs in field primary food webs.
Mai, You-shiang, i 麥祐翔. "Assemblage structure and polycyclic aromatic hydrocarbons accumulation of zooplankton in the Gaoping coastal waters". Thesis, 2016. http://ndltd.ncl.edu.tw/handle/79369969746280633793.
Pełny tekst źródła國立中山大學
海洋生物科技暨資源學系研究所
104
Polycyclic aromatic hydrocarbons (PAHs) are one of the persistent organic (POPs), which have the following characteristics: carcinogenic, bioaccumulation, biomagnification and long-distance shift with the atmosphere and biology. PAHs are mainly produced by the incomplete combustion of wood, coal and fossil fuels, influencing the land and marine ecosystems. Zooplankton are the primary consumer and play an important role in the marine food web. The observation of the PAHs accumulation in zooplankton provides us with more knowledge, which is essential information to further understand the spread of PAHs in the marine ecological environment. Zooplankton samples were collected at 16 stations in the Gaoping coastal waters from three Ocean Research III cruises: August, December 2014 and April 2015. Significant seasonal difference in zooplankton abundance was observed in the study, with the higher mean abundances in December (1246 ± 399 ind./m3) and April (1371 ± 521 ind./m3) than in August (463 ± 80 ind./m3). In general, copepods are the most dominant group (with a relative abundance >70%) at all sampling stations, except for April at station 1 (cladocera, 74%). The PAHs concentration of zooplankton ranged between 25 and 5440 ng / g dw. Higher PAHs concentrations were noted in Gaoping River estuary transect than in transects of Kaohsiung harbor and Fangshan. However, in terms of PAHs concentration of zooplankton biomass in seawater, PAHs concentration changed between 4 and 203 ng/m3, and the higher concentrations were found in Gaoping River estuary transect. Six PAHs, 1-Methylnaphthalene, 2-Methylnaphthalene, 2,6-Dimethylnaphthalene, Phenanthrene, Fluoranthene and Pyrene, produced by petroleum and petrochemical fuel, were the most abundant components in zooplankton in the study. They are common low rings PAHs in the marine environment. Among the above-mentioned components, the concentration of 2,6-Dimethylnaphthalene showed significant negative correlation with zooplankton abundance. The results demonstrated that the Gaoping coastal waters have been greatly influenced by petroleum pollutions produced from shipping and industrial activities. Keywords: Zooplankton, POPs, Gaoping coastal water, Assemblage structure, Bioaccumation
Lee, Yi-Hwar, i 李貽華. "Studies on the accumulation of polycyclic aromatic hydrocarbons (PAHs) in plant leaves and the techniques for biomonitoring". Thesis, 2005. http://ndltd.ncl.edu.tw/handle/49761380975295617766.
Pełny tekst źródła國立中興大學
生命科學系
93
Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous in the environment. PAHs are by-products of the incomplete combustion or pyrolysis of organic materials or plastics. Incineration, internal combustion engines, industrial activities and residential heating all are important sources of PAHs. PAHs are a major health concern because many kinds of PAHs are carcinogenic and mutagenic. PAHs persist in the environment and may accumulate in vegetation. In Taiwan, there were only few studies concerning the effects of PAHs on plants as well as the uptake and accumulation of PAHs in plants. Four items were studied in this research, including: (1) to set up the adequate analytical method of PAHs in vegetation and in air; (2) to investigate the accumulation of PAHs in plants in the vicinity of different pollution sources; (3) to evaluate the scale of polluted area from pollution source by the PAHs accumulation in plants; (4) to choose the suitable plant species as indicators for active or passive biomonitoring PAHs in the environment. The extraction and analysis of PAHs from plant tissues are essential steps for determining PAHs accumulation. This study developed a precise method for simultaneous detecting 16 PAHs by high performance liquid chromatography (HPLC) with fluorescence or UV detector. Leaf samples were extracted with dichloromethane solvent. The extract was then cleaned up by aluminum oxide column before being subjected to HPLC analysis. The correlation coefficients of calibration curve of 16 PAHs were 0.9950 - 0.9999. For the 11 tested plant species, all the 16 PAHs contents in leaves could be simultaneously determined by this developed method. The detection limits of 16PAHs were 1.27 - 8.21 ng g-1. Among the 94 leaf samples from different sites in the vicinities of pollution sources, 18 samples were detected with PAHs contents. That implied that PAHs accumulation was found in the plants in the polluted areas in Taiwan. Bidens pilosa var. radiata accumulated higher levels of PAHs than the other species. Kinds of PAHs in leaves varied with pollution sources. Phenanthrene and pyrene were detected in leaves of B. pilosa var. radiata from the vicinity of incinerator. Phenanthrene, fluoranthene, pyrene and chrysene were detected in B. pilosa var. radiata from the industrial area. An opportunity arose to examine the factors that govern the dispersion of PAHs following a massive waste plastic fire at Yunlin, central Taiwan, on Dec. 7 of 2002. With the aim of investigating the applicability of biomonitoring for PAHs contamination, leaves of Mangifera indica, Broussonetia papyrifera and B. pilosa var. radiata were collected from 11 sites in the vicinity of the burned warehouse after the large-scale waste plastic fire, and were analyzed for 16 PAHs. B. pilosa var. radiata leaves contained higher PAHs than M. indica and B. papyrifera. The concentration of ΣPAHs in leaves of B. pilosa var. radiata, M. indica and B. papyrifera on site SW4 (400m southwest from the warehouse) was 2221.9, 940.3 and 1158.0 ng g-1 f.w., respectively. The levels of ΣPAHs in leaves declined as the distance from the burned warehouse increased. The zone of contamination was estimated to be less than 700m from this plastic fire. The concentrations of PAHs in leaves declined rapidly with time. B. pilosa var. radiata, M. indica and B. papyrifera accumulated high levels of PAHs and could be used as passive biomonitors to evaluate gradient of atmospheric PAHs contamination after a plastic fire. B. pilosa var. radiata, that is one kind of widespread naturalized vegetation and is relatively tolerant to PAH pollution, is a suitable species in Taiwan for monitoring PAHs pollution through leaf analyses. B. pilosa var. radiata accumulated higher level of PAHs than the other species both in the vicinity of incinerators and after a plastic fire. It showed no injured symptoms. In this study, B. pilosa var. radiata were studied for active and passive biomonitorings. The concentrations of 3- and 4-ring PAHs (phenanthrene, pyrene and chrysene), instead of 5- and 6-ring PAHs, were detected among all the B. pilosa var. radiata samples in the vicinity of incinerator. The concentrations of PAHs increased with time in active biomonitoring. The accumulation of PAH in B. pilosa var. radiata yielded useful information on the deposition of PAH and was a good indicator of pollution. B. pilosa var. radiata can be easily cultivated and widespread installed in the vicinity of pollution source and is suitable to be used as accumulator for active biomonitoring of PAHs pollution.
Simão, Fátima Cristina Paulino. "Ecotoxicological assessment of PAHs using the freshwater planarian Girardia tigrina". Doctoral thesis, 2020. http://hdl.handle.net/10773/28868.
Pełny tekst źródłaAs planárias de água doce são animais que possuem uma variedade de carac-terísticas que as tornou fundamentais para várias áreas do conhecimento, tais como a investigação em células estaminais, a neurofarmacologia ou a investi-gação sobre envelhecimento. O interesse por estes animais deve-se a atributos únicos como a existência de células estaminais distribuídas pelos seus corpos, a presença de um cérebro simples, mas com semelhanças ao sistema nervoso dos vertebrados, ou a sua aparente ausência de envelhecimento. O interesse pelas planárias como animais experimentais difundiu-se à área da investigação ecotoxicológica, não só devido à sua fácil manutenção em contexto laboratorial e sensibilidade a contaminantes ambientais, mas também à vasta gama de respostas que podem ser usadas para avaliar a teratogénese, a carcinogénese, a toxicidade comportamental e reprodutiva ou a neurotoxicidade. Para além disto, as planárias podem ser usadas em testes com múltiplas espécies como invertebrados epibentónicos predadores. Neste contexto, o presente trabalho pretendeu explorar os parâmetros ecotoxicológicos das planárias de água doce em resposta a contaminantes ambientais, através da utilização de hidrocarbo-netos aromáticos policíclicos (PAHs) como compostos modelo. Os PAHs são contaminantes ubíquos no ambiente, devido à variedade de fontes emissoras, tanto naturais, como antropogénicas, e à sua capacidade de serem transporta-dos através do ar por longas distâncias. Contudo, a avaliação de risco ambien-tal dos PAHs tem-se mostrado difícil, devido à variabilidade das capacidades de metabolização destes compostos nos invertebrados e à grande variedade de efeitos que os PAHs podem provocar nos organismos. Para alguns grupos de invertebrados, como é o caso das planárias, os efeitos destes compostos são (quase) desconhecidos. No sentido de explorar a potencial utilização das planá-rias de água doce no contexto da ecotoxicologia, este trabalho utilizou a espé-cie Girardia tigrina como organismo modelo e três PAHs com diferentes núme-ros de anéis aromáticos, o fenantreno, o pireno e o benzo[a]pireno (B[a]P), de 3, 4 e 5 anéis aromáticos, respetivamente. Foram delineados vários objetivos específicos: o desenvolvimento de ensaios para a avaliação dos parâmetros ecotoxicológicos nas planárias de água doce, a avaliação da toxicidade dos PAHs e a potencial acumulação dos PAHs em diferentes cenários de exposi-ção. Ao longo de 6 capítulos experimentais, os protocolos para a avaliação dos parâmetros ecotoxicológicos foram refinados e, mais especificamente, foi de-senvolvido um protocolo para avaliar a inibição alimentar de acordo com as características específicas da planária G. tigrina. Também se verificou que esta espécie de planária é sensível aos PAHs, tendo sido observada mortalidade, desintegração de tecidos, atrasos na regeneração, alterações comportamen-tais, alterações bioquímicas, diminuição da taxa reprodutiva e efeitos em planá-rias recém-nascidas. A severidade dos efeitos observados aumentou de acordo com as concentrações internas de PAHs nos tecidos das planárias. No entanto, apesar das semelhanças químicas entre os compostos, cada um dos PAHs provocou diferentes efeitos nas planárias. A avaliação da taxa de alimentação e locomoção mostrou ser sensível em resposta aos contaminantes em exposi-ções de curta duração, e evidenciou o potencial destes parâmetros para a ava-liação ecotoxicológica. Em períodos de exposição mais longos, a fecundidade mostrou ser um parâmetro sensível. Para além disso, através da observação dos recém-nascidos resultantes de progenitores expostos ao B[a]P, foi verifica-do que estes apresentavam anomalias comportamentais, evidenciando, assim, a importância da avaliação da condição dos recém-nascidos como um parâme-tro reprodutivo e em exposições multigeracionais. Constatou-se ainda que, nos tecidos das planárias, os PAHs se acumularam em maior quantidade na zona cefálica, potencialmente indicando que estes compostos poderão ser neurotóxi-cos para as planárias, como sugerem também as alterações comportamentais. Para além disto, a bioacumulação de PAHs em planárias expostas a sedimen-tos contaminados ou que consumiram presas contaminadas com B[a]P, de-monstrou o potencial destes animais para testes de avaliação ecotoxicológica de sedimentos e na avaliação da transferência trófica de contaminantes. Os resultados obtidos no presente trabalho indicam que as planárias são sensíveis a contaminantes, permitem a avaliação de uma grande variedade de parâme-tros e podem também ser usadas como predadores em testes com múltiplas espécies. Assim, a utilização das planárias de água doce para a investigação ecotoxicológica é fortemente recomendada.
Programa Doutoral em Biologia e Ecologia das Alterações Globais