京都大学 / 0048 / 新制・論文博士 / 博士(農学) / 乙第13262号 / 論農博第2875号 / 新制||農||1071(附属図書館) / 学位論文||R1||N5217(農学部図書室) / (主査)教授 山下 洋, 教授 澤山 茂樹, 教授 吉岡 崇仁 / 学位規則第4条第2項該当 / Doctor of Agricultural Science / Kyoto University / DFAM

Les observations et expériences ont montré que le dépôt d'aérosols pouvait entraîner une augmentation de la quantité de nutriments disponible et ainsi favoriser la production biologique de la mer Méditerranée. Dans ce contexte, cette étude propose pour la première fois une quantification des effets du dépôt d'aérosols en provenance de sources variées sur la biogéochimie de l'ensemble de la mer Méditerranée grâce à un modèle couplé physique-biogéochimie haute résolution NEMOMED12/PISCES. L'étude consiste à modéliser et analyser les effets du dépôt d'azote et de phosphate en provenance de sources naturelles et anthropiques sur la biogéochimie de la Méditerranée. Pour cela,des modèles atmosphériques régionaux et globaux permettant de représenter le dépôt d'aérosol ont été évalués et sélectionnés. Le modèle NEMOMED12/PISCES a été adapté pour prendre en compte ces nouvelles sources de nutriments. L'analyse des simulations a permis de montrer que le dépôt atmosphérique représente environ 10 % des apports externes totaux de nitrates et 5 à 30 % des apports de phosphate en moyenne sur l'ensemble du bassin. Le dépôt peut également entraîner une augmentation de la production biologique jusqu'à 50 % grâce à la levée des limitations en nutriments. Les effets des changements climatiques pourraient avoir des conséquences particulièrement importantes sur une région sensible comme la Méditerranée. C'est pourquoi les évolutions de la biogéochimie du bassin dans un scénario de changement climatique ont été évalués au cours de cette thèse. Pour cela, le modèle NEMOMED8/PISCES a été utilisé avec des forçages physiques et biogéochimiques qui correspondent au scénario d'évolution des conditions climatiques A2 du GIEC. Cette étude met en évidence une diminution de la productivité biologique de surface de 10 % en moyenne dans l'ensemble du bassin en réponse à l'échauffement et à la stratification. Les limitations en nutriments sont fortement modifiées et la sensibilité de la Méditerranée au dépôt atmosphérique de nutriments change. Les résultats de cette thèse soulignent l'importance de l'atmosphère comme source de nutriments et en particulier d'azote et de phosphate. Les effets du dépôt atmosphérique sont variables en fonction de la saison et de la localité du dépôt et ont tendance à être plus significatifs lorsque les eaux de surface sont limitées en nutriments. En n tout bouleversement de la productivité biologique est transmis rapidement le long de la chaîne trophique. Les résultats obtenus pourraient être précisés avec l'amélioration des modèles atmosphériques et l'obtention de nouvelles mesures de flux de dépôt et l'amélioration des connaissances sur les transformations physico-chimiques subies par les aérosols avant et après leur dépôt en milieu océanique. Par ailleurs, des scénarios plus précis concernant les changements climatiques sont nécessaires afin d'évaluer les évolutions des conditions biogéochimiques de la Méditerranée. Enfin, les récents développements du modèle PISCES peut à présent permettre d'étudier la Méditerranée dans un contexte non redfieldien. / Observations and experiments showed that aerosol deposition can increase the amount of bioavailable nutrients and favor biological production of the Mediterranean Sea. In this context, the present study yields for the first time a quantification of the effects of aerosol deposition from various sources thanks to the coupled physical-biogeochemical model NEMOMED12/PISCES. This study consists in modeling and analyzing the effects on the Mediterranean biogeochemistry of atmospheric deposition of nitrogen and phosphate from various natural and anthropogenic sources. For this purpose, regional and global atmospheric models representing aerosol deposition were evaluated and selected. The NEMOMED12/PISCES model was modified to take into account these new nutrient sources. The analysis of the simulations showed that atmospheric deposition accounts for approximately 10 % of total external nitrate supply and 5 to 30 % of phosphate supply on average over the entire basin. Aerosol deposition can also increase biological production up to 50 % thanks to the lowering of nutrient limitations. The maximal fertilizing effects are observed during the stratied period which, in the Mediterranean region, is summer. The effects of climate change may be particularly important in sensitive regions such as the Mediterranean. Therefore, the evolutions of basin scale biogeochemistry were evaluated under a climate change scenario. The NEMOMED8/PISCES model was used with physical and biogeochemical forcings for the IPCC A2 climate change scenario. This study shows a reduction in basin scale surface productivity by approximately 10 % triggered by warming and stratification. Nutrient limitations are modified and the Mediterranean Sea sensibility to atmospheric deposition changes. The results of this thesis underline the importance of atmosphere as a nutrient source, in particular for nitrogen and phosphate. Deposition effects vary according to the season and the location. They are more important during the stratied period, when surface water is nutrient limited. Also, any change in biological productivity is quickly transfered along the biological chain. To refine the results, the atmospheric models could be improved and more knowledge on deposition fluxes and physical and chemical transformations of aerosols before and after deposition would be necessary. Moreover, more precise scenarios concerning climate change effects would be necessary in order to study the future evolutions of biogeochemical conditions in the Mediterranean. Finally, the recent developments on the PISCES model make new studies possible in a non redfieldian context. Preliminary results indicate that the productivity of the different phytoplanktonic groups varies with intracellular C/N/P ratios.

Made available in DSpace on 2016-06-02T19:56:56Z (GMT). No. of bitstreams: 1 6181.pdf: 2281247 bytes, checksum: ab77d4d6451a6d9054abc19310067ed2 (MD5) Previous issue date: 2014-03-25 / Financiadora de Estudos e Projetos / This study aimed to evaluate the influence of the hydraulic retention time (HRT) on hydrogen production using crude glycerol as a substrate in an anaerobic fluidized bed reactor (AFBR ) . The reactor had a volume of 1979 cm3, which was varied HDT in eight stages: Stage I, II, III, IV, V, VI , VII, VIII with HDT of 14, 12 , 10,8 , 6, 4 , 2 and 1 hour. The temperature was controlled at 55 °C, fixing the substrate concentration in the amount of 5 gL -1 . The inoculum used was granular sludge from the thermophilic anaerobic reactor and upflow sludge blanket ( UASB ) for the treatment of vinasse, located at Usina São Martinho , Pradópolis - SP . The results showed that the yield of hydrogen (HY) remained constant between the HDT of 2h to 14h (1.2 H2.mol glycerol and 1.4 mol -1) HRT of 1h and the yield was higher ( 3 moles H2 . glycerol mol -1). The volumetric H2 production was increased with decreasing HRT , with its maximum value of 1508.7 mL.h - 1.L - 1 in lower applied TDH (1h) . The biogas produced was composed of CO2 and H2. The composition varied with the decrease in HRT from 14 to 2h (Step IVII ) in the first seven stages (14 to 2 h ), reaching a mean rate between 50 and 60%. In the last phase, which HRT was 1h , the percentage of H2 biogas reached the maximum value of 70 % . The major metabolites obtained during the first seven stages of operation of the reactor were: Acetic acid (4.5 to 18%), butyric acid (4.3 to 21% ), ethanol (14 to 29%) and 1,3-propanediol (34 to 50%). As for 1h note the HDT of the presence of propionic acid (56%), acetic acid ( 11.5%) and 1,3- propanediol ( 30%). / Este estudo teve como objetivo avaliar a influência do tempo de detenção hidráulica (TDH) sobre a produção de hidrogênio, utilizando glicerol bruto como substrato em reator anaeróbio de leito fluidizado (RALF). O reator possuía um volume de 1979 cm3, no qual se variou o TDH em oitos fases: Fase I, II, III, IV, V, VI, VII, VIII com os respectivos TDH de 14, 12, 10,8, 6, 4, 2, e 1 hora. A temperatura foi controlada à 55 oC, fixando a concentração no valor de 5 g.L-1 de DQO. O inóculo utilizado foi proveniente de lodo granulado do reator termofílico anaeróbio de fluxo ascendente e manta de lodo (UASB) para o tratamento de vinhaça, localizado na Usina São Martinho, Pradópolis-SP. Os resultados mostraram que o rendimento de hidrogênio (HY) permaneceu constante entre os TDH de 14h à 2h (1,2 e 1,4 mol H2.mol glicerol-1) e no TDH de 1h o rendimento foi maior (3 mol H2.mol glicerol-1). Já a produção volumétrica de H2, sob a pressão de à 1 atm e temperatura de 55 oC, teve aumento com a diminuição do TDH, sendo seu valor máximo de 1508,7 mL.h-1.L-1 no menor TDH aplicado (1h). O biogás teve como principias compostos CO2 e H2. A composição de H2 no biogás variou com a diminuição do TDH de 14 para 2h (Fase I a VII) nas sete primeiras fases (14 a 2 h) atingindo um valor médio percentual entre 50 e 60 %. Na última fase, cujo TDH foi de 1h, o percentual de H2 biogás atingiu o valor máximo de 70%. Os principais metabólitos obtidos durante as sete primeiras fases de operação dos reatores foram: ácido acético (4,5 a 18%), ácido butírico (4,3 a 21%), etanol (14 a 29%) e 1,3-propanodiol (34 a 50%). Já para o TDH de 1h nota-se a presença de ácido propiônico (56%), ácido acético (11,5%) e 1,3-propanodiol (30%).

Sedimentation rates and compositions of sinking particles were investigated at three sites on the Beaufort slope and one in Canada Basin during the period 1990-1994 using moored sequential sediment traps. A method was developed to identify the terrigenous and biogenic components of the fluxes. The physical context including ice cover, ocean currents, river inputs, winds, air temperature, incident light, and nutrient availability provide essential information to the interpretation of the particle fluxes and to the understanding of shelf-basin sediment transport in this area. Eddies, internal waves, upwelling and downwelling, and the state of the ice cover all played important and overlapping roles in the pattern of observed fluxes. A peak in the flux of highly terrigenous material under complete ice cover in mid-winter to the northwest of Mackenzie Trough was associated with predominantly downwelling conditions and the passage of a series of eddies and internal waves. A prolonged spring diatom bloom occurred in the mid-slope area and was clearly associated with an early opening of the ice on the east side of the shelf. Higher fluxes at the Canada Basin site were associated with a large eddy clearly identifiable from the current-T-S record and also from the composition of the suspended material carried with it. At the base of the slope (2700 m), the composition was highly terrigenous and remarkably consistent. Higher up the slope (700 m), biogenic peaks in the summer diluted the terrigenous material briefly, but it appears that there is a constant background of highly terrigenous material. There was a high degree of variability between sites and over the slope there was not enough data to asses the inter-annual variability. In Canada Basin, the inter-annual variability was closely linked to the extent of open water in the summer period. At all sites, lateral transport is clearly indicated by the increase in flux with depth. The data robustly demonstrate the need for detailed knowledge of physical processes for informed interpretation of particle fluxes and sediment transport in this area.