Les systèmes aquatiques continentaux sont des vecteurs majeurs du cycle global du carbone, recevant une quantité importante de carbone qu’ils émettent vers l’atmosphère et exportent aux océans. Nous caractérisons les concentrations et les transferts de toutes les formes carbonées à l’interface eau souterraine-ruisseau-atmosphère, dans un bassin versant de plaine, tempéré, forestier et sablonneux, où l’hydrologie se produit majoritairement au travers du drainage des eaux souterraines. Nous suivons différentes stations couvrant l’ensemble de la variabilité du bassin, depuis les eaux souterraines jusqu’à l’exutoire, avec des proportions variables d’occupation du sol. Le DOC est exporté majoritairement en périodes de crues alors que la même quantité de DIC est exportée entre périodes de crues et d’étiages. Le carbone terrestre dérivé des sols forestiers est la source principale de carbone dans les eaux superficielles et seulement 3% de la NEE est exportée. L’occupation du sol modifie localement les formes de carbone dans les ruisseaux mais à l’échelle du bassin la forêt prédomine. Nous quantifions le dégazage de CO2 en s’appuyant sur un bilan de masse isotopique. Environ 75% du dégazage total se produit dans les ruisseaux de premiers et de seconds ordres, qui se comportent comme des points chauds pour l’émission de CO2. Ce travail de thèse contribue à une meilleure définition du rôle des ruisseaux et des rivières dans le cycle global du carbone. De manière plus précise, il améliore les connaissances sur la proportion du pompage biologique de CO2 atmosphérique d’un écosystème qui est exportée vers le réseau hydrographique, ainsi que le devenir de ce carbone en aval. / Inland waters are a major component of the global carbon cycle. These systems receive a significant amount of carbon from aquatic and terrestrial sources. A part of this carbon is degassed in the atmosphere while another is exported to the oceans. We characterize the concentrations and transfers of all carbon forms at the groundwater-stream-atmosphere interface, in a temperate, forested and sandy lowland watershed, where hydrology occurs in majority through drainage of groundwater. We monitored contrasting study site representative of the diversity of the ecosystem, from groundwater to river mouth, with different proportion of land use. DOC is exported in majority during high flow periods whereas the same amount of DIC is exported between high and base flow periods.Terrestrial carbon that originates from soils forests is the major source of carbon in surface waters but only 3% of the NEE is exported. Land use modifies locally the different forms of carbon in streams but at the basin scale forests predominate. We quantify the degassing ofCO2 based on fairly well balanced isotopic mass balance. About 75% of the total degassing occurs in first and second order streams, which behave as hotspots for CO2 degassing. This work contributes to a better definition of the role of streams and rivers in the global carboncycle. Specifically, this work enhances understanding on the proportion of CO2 pumped byan ecosystem and then exported to the river system, as well as the fate of this carbon downstream.

Subalpine ecosystems are experiencing rapid changes in snow pack, temperature, and precipitation regime as a result of anthropogenic climate forcing. These changes in climate can have a profound effect on subalpine ecosystem structure and functioning, which may ultimately feed back to climate change. In this study, I examined the response of the subalpine meadow plant communities at the Rocky Mountain Biological Laboratory to natural and simulated climate change. First, I looked at whether changes in growing season precipitation or temperature regime would have the larger effect on subalpine ecosystem carbon flux. In a simulated warming experiment, changes in growing season precipitation had a tenfold larger effect on cumulative carbon flux than did the warming treatment. Along a natural climatic and elevational gradient, precipitation stimulates carbon uptake, particularly at higher elevations. Given projected decreases in summer precipitation in the high elevation Rockies, we predict a 20% decrease in carbon uptake from subalpine meadows. Second, I compared the taxonomic, phylogenetic and functional structure of plant communities along an elevational gradient to infer which climatic and biotic factors influence community assembly at each elevation. Floral and phenology traits become overdispersed at high elevation, mirroring phylogenetic relatedness, and suggesting pressure to diversify to attract pollinators during the abbreviated growing season. At the same time, leaf functional traits become clustered at high elevation, indicating multiple opposing assembly mechanisms in subalpine communities. Finally, I studied the natural history of sagebrush, Artemisia tridentate ssp. vaseyana, at its elevational range limit in subalpine meadows. In particular, I focused on the importance of warming and species interactions in elevational advance of the species. I found that facilitation by neighboring forbs was critical for sagebrush seedling survival, decreasing mortality by 75%. Seedling mortality was overwhelmingly due to desiccation of seedlings; therefore, neighboring forbs moderate temperature and water stress for seedlings. Despite the extremely limited growing season at high elevation caused by subfreezing temperatures, subalpine ecosystem structure and function are closely tied to water availability during the growing season. Therefore, improved predictions of future precipitation regimes over the Rocky Mountains will be our best tool for conservation of these fragile habitats.

Thesis (M.A.)--香港中文大學硏究院神學學部. / Includes bibliographical references: leaves 285-299. / Thesis (M.A.)--Xianggang Zhong wen da xue yan jiu yuan shen xue xue bu. / 前言 --- p.1-9 / Chapter 第一章 --- 倪拆聲的生平及時代背景 / Chapter ´¡ --- 引言 --- p.10-12 / Chapter ´Ł --- 早期生活（一九○三´ؤ一九二一） --- p.12-21 / Chapter ´Ø --- 初期工作時期（一九二二´ؤ一九二七） --- p.22-33 / Chapter ´Ð --- 獨立工作發展期（一九二八´ؤ一九三四） --- p.34-44 / Chapter ´Þ --- 工作的再思想前後期（一九三五´ؤ一九四二） --- p.44-56 / Chapter ´Æ --- 後期的生活（一九四三´ؤ一九七二） --- p.56-72 / Chapter 第二章 --- 倪拆聲的教會觀念的探討 / Chapter ´¡ --- 引言 --- p.73-76 / Chapter ´Ł --- 前期´ؤ´ؤ一九四五年前對教會的基本觀念 / Chapter 一 --- 教會的意義及本質 --- p.77-80 / Chapter 二 --- 教會的類型 --- p.80-84 / Chapter 三 --- 地方和地方教會的意義 --- p.84-86 / Chapter 四 --- 地方教會與使徒（工人） --- p.86-107 / Chapter 五 --- 地方教會的組織及工作 --- p.107-122 / Chapter ´Ø --- 後期´ؤ´ؤ一九四五年對教會觀念的一些基本改變 / Chapter 一 --- 工作中心的地方教會與普通的地方教會之別 --- p.123-127 / Chapter 二 --- 使徒與長老的關係 --- p.127-129 / Chapter 三 --- 教會中的權柄與順服 --- p.129-134 / Chapter 四 --- 使徒間「工作團體」性質的改變 --- p.134-136 / Chapter 五 --- 使徒質素的要求 --- p.136-138 / Chapter 六 --- 信心事業的處理及使徒的經濟問題 --- p.139-140 / Chapter 七 --- 福音移民的推行 --- p.141-146 / Chapter 第三章 --- 倪拆聲教會觀中主要觀念的討論及批評 / Chapter ´¡ --- 引言 --- p.147-148 / Chapter ´Ł --- 對倪拆聲的教會觀中幾個主要觀念的討論及批評 / Chapter 一 --- 教會的意義及本質問題 --- p.149-174 / Chapter 二 --- 「地方教會」及「字派」問題 --- p.175-188 / Chapter 三 --- 「使徒」和「工作」的問題 --- p.188-213 / Chapter 第四章 --- 聚會所的發展與其在中國教會史中的地位 / Chapter ´¡ --- 引言 --- p.214-215 / Chapter ´Ł --- 「聚會所」發展原因的探讨 / Chapter 一 --- 迎合民族主義的浪潮 --- p.216-226 / Chapter 二 --- 配合時代背景的需求 --- p.227-235 / Chapter 三 --- 「使徒」身份的特性 --- p.235-259 / Chapter 四 --- 教會總動員的力量 --- p.239-247 / Chapter ´Ø --- 「聚會所」在近代中國教會史中的表現和批評 / Chapter 一 --- 在「本色教會」運動中的表現 --- p.247-255 / Chapter 二 --- 在「平信徒訓練」運動中的表現 --- p.255-263 / Chapter 三 --- 對「讀經態度」和「字派」的表現 --- p.263-276 / 結語 --- p.277-284 / 參考書目 --- p.285-299

Submitted by Renata Lopes (renatasil82@gmail.com) on 2016-02-02T13:25:14Z No. of bitstreams: 1 elizetefernandesdossantos.pdf: 662416 bytes, checksum: 61183744e4819726616088a36fde8ee2 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2016-02-02T13:55:44Z (GMT) No. of bitstreams: 1 elizetefernandesdossantos.pdf: 662416 bytes, checksum: 61183744e4819726616088a36fde8ee2 (MD5) / Made available in DSpace on 2016-02-02T13:55:44Z (GMT). No. of bitstreams: 1 elizetefernandesdossantos.pdf: 662416 bytes, checksum: 61183744e4819726616088a36fde8ee2 (MD5) Previous issue date: 2014-01-27 / O objetivo desta dissertação é analisar se a existência de um serviço de apoio à inclusão, especificamente a Sala de Recursos, contribui para o processo de inclusão dos alunos com deficiência nas escolas estaduais mineiras. Para isso, realizamos pesquisa comparativa entre duas escolas situadas nos municípios de Mariana e Ouro Preto, das quais apenas uma possui o serviço de Sala de Recursos. Para efeito de escolha foi levado em consideração o fato de em ambas as escolas haver o atendimento a um número significativo de alunos com necessidades educacionais especiais (NEEs). Por conta de a escola em que funciona a Sala de Recursos atender apenas a alunos das séries iniciais do Ensino Fundamental e a outra escola prestar atendimento a alunos das séries iniciais e finais desse nível de ensino, para efeito de comparação, elegemos como foco de análise apenas o atendimento a alunos das séries iniciais do Ensino Fundamental, ou seja, alunos do primeiro ao quinto ano. No processo investigativo foram utilizados métodos qualitativos tais como análise documental, entrevistas com professores e gestores bem como observação participante. Dentre os documentos analisados estão a Proposta Político Pedagógica (PPP) das escolas e fichas de desempenho dos alunos atendidos na sala de recursos bem como dos alunos com deficiência, matriculados na escola que não possui esse tipo de atendimento. Para este estudo, tomamos como base o período de 2011 e 2012. / The goal of this dissertation is to examine whether the existence of an inclusion support service, specifically the Office of resources, contributes to the process of inclusion of students with disabilities in State schools of Minas. For this, we carry out comparative research between two schools located in the municipalities of Mariana and Ouro Preto, of which only one has the Resource Room service. For the purpose of choice was taken into consideration the fact that both schools be the attendance to a significant number of students with special educational needs (NEEs). On behalf of the school resource Room works meet only the pupils of the initial series of elementary school and another school provide assistance to students of initial and final series of this level of education, for comparison, we have chosen as a focus of analysis only service for students of the initial series of elementary school, IE, students from the first to the fifth year. In the investigative process have been used qualitative methods such as analysis of documents, interviews with teachers and administrators as well as participant observation. Among the documents analysed are Political Pedagogical Proposal (PPP) of schools and student performance chips served in the living room as well as resources of the students with disabilities enrolled in school that does not have this kind of care. For this study, we take as a basis the period 2011 and 2012.

Submitted by Nadir Basilio (nadirsb@uninove.br) on 2017-06-14T19:00:58Z No. of bitstreams: 1 Carla Campos de Oliveira Almeida.pdf: 1354143 bytes, checksum: 2420d5c8ec754313727112b6689e96af (MD5) / Made available in DSpace on 2017-06-14T19:00:58Z (GMT). No. of bitstreams: 1 Carla Campos de Oliveira Almeida.pdf: 1354143 bytes, checksum: 2420d5c8ec754313727112b6689e96af (MD5) Previous issue date: 2017-03-31 / The evaluation of learning serves as a dynamic instrument of pedagogical practices, especially when the educational scenario It is crossed by the inclusion movement. The research proposal is to understand and reflect on the evaluative practices of regular teachers and elementary school teachers (1st to 5th year) of the municipality of Extrema – MG, of students with special educational needs. The research problem was delineated from concerns presented by the teachers who work with these students in the schools of the municipality, such as: how to evaluate students with SEN? What notes to assign? These questions led to the search for interlocutors directly involved with the problem, Mainly teachers from municipal schools who attended in regular education the largest number of students with SEN per class. It is about a case study. The work brings together reflections that emerged from the theoretical elaborated and analysis of the data obtained in teachers' reports and the questionnaires answered by them, As well as observations of everyday school life and also of the comparison with the guidance documents of the Municipal Department of Education that are included in the Municipal Plan of Education (2015 to 2024). The conclusions indicate conceptual tensions over the student with disabilities, Their possibilities of learning and their educational evaluation. The analysis of tensions leads to considerations, rather than to conclusions, that they intend to collaborate to deepen the discussions on such an important topic for educators who work with these students and, even more, for themselves. / La valorización de los aprendizados sirve como instrumento dinámico de las prácticas pedagógicas, principalmente cuando el escenario educacional es atravesado por el movimiento de inclusión. La propuesta de la pesquisa es comprender y reflejar sobre las prácticas de evaluación de los professores de enseñanza regular y de la enseñanza fundamental I (1º al 5º año) del Municipio de Extrema MG, utilizados con alumnos con necesidades educacionales especiales. El problema de la investigación fue delineado a partir de preocupaciones presentadas por los professores que actúan con estos alumnos en las escuelas del Municipio, tales como: ¿como evaluar los alunos com NEE? ¿Que notas atribuirle? Estas questiones llevaron a la búsqueda por interlocutores directamente relacionados com el problema, principalmente profesores de las escuelas municipales que atendían en la enseñanza regular el mayor número de alumnos com NEE por salón. Se trata de um estúdio de caso. El trabajo reúne reflexiones que emergieron del referencial teórico elaborado y análisis de los datos obtenidos en relatos de profesoras y en los cuestionarios respondidos por ellas, bien como de observaciones del cotidiano escolar y, todavia, de la comparación con documentos de orientación de la Secretaría Municipal de Educación que constan em el Plan Municipal de Educación (2015 a 2024). Las conclusiones indican tensiones conceptuales sobre el alumno con discapacidad, sus posibilidades de aprendizado y su evaluación educacional. El análisis de esas tensiones lleva a consideraciones, más de que a conclusiones, que tiene la intención de colaborar para aprofundarse en las discusiones a respecto de um tema tan importante para los educadores que trabajan com estos alunos y, más todavia, para ellos propios. / A avaliação das aprendizagens serve como instrumento dinâmico das práticas pedagógicas, principalmente quando o cenário educacional é atravessado pelo movimento de inclusão. A proposta da pesquisa é compreender e refletir sobre as práticas avaliativas dos professores de ensino regular do ensino fundamental I (1º ao 5º ano) do município de Extrema - MG, utilizadas com alunos com necessidades educacionais especiais. O problema de pesquisa foi delineado a partir de preocupações apresentadas pelas professoras que atuam com estes alunos nas escolas do município, tais como: como avaliar os alunos com NEE? Que notas atribuir? Estas questões levaram à busca por interlocutores diretamente envolvidos com a problemática, principalmente professores das escolas municipais que atendiam no ensino regular o maior número de alunos com NEE por turma. Trata-se de um estudo de caso. O trabalho reúne reflexões que emergiram do referencial teórico elaborado e análise dos dados obtidos em relatos de professoras e nos questionários respondidos por elas, bem como de observações do cotidiano escolar e, ainda, do cotejo com os documentos de orientação da Secretaria Municipal de Educação que constam do Plano Municipal de Educação (2015 a 2024). As conclusões indicam tensões conceituais sobre o aluno com deficiência, suas possibilidades de aprendizagens e sua avaliação educacional. A análise dessas tensões leva a considerações, mais do que a conclusões, que têm a intenção de colaborar para o aprofundamento das discussões a respeito de tema tão importante para os educadores que trabalham com estes alunos e, mais ainda, para eles próprios.

京都大学 / 0048 / 新制・論文博士 / 博士(農学) / 乙第12985号 / 論農博第2825号 / 新制||農||1038(附属図書館) / 学位論文||H28||N4960(農学部図書室) / 32455 / 京都大学大学院農学研究科林学専攻 / (主査)教授 谷 誠, 教授 北山 兼弘, 教授 舟川 晋也 / 学位規則第4条第2項該当 / Doctor of Agricultural Science / Kyoto University / DFAM

Made available in DSpace on 2014-07-29T15:16:27Z (GMT). No. of bitstreams: 1 Dissert Leslivan Ubiratan de Moraes.pdf: 723767 bytes, checksum: 88adcd404b3c30cc9f22d95b44bd13b3 (MD5) Previous issue date: 2008-04-16 / The jurubeba was identified that such species was Solanum scuticum M. Nee, from which pharmacognostic and morphanatomic data were not available to Goiás. Because of that, we tried some complementary data. For the morphoanatomic evaluation of the leaves some cuts were carried out as described by Kraus and Arduin (1997). For the phytochemical trial, it was used some methodologies as described by Costa (2001). With the phytochemical screening, were identified alkaloids, flavonoids, coumarins, anthraquinones and saponins in prospecting phytochemical. Both in phytochemical trial, as in the phytochemical prospection, it was found alkaloids. Due to the biological activities of these secondary metabolites, we obtained the alkaloid fraction, using the dust of the leaves, and we got the ethanol extract. The fractions were divided by polarity and they were evaluated by thin-layer chromatography. Microbiological evaluation was carried out to verify possible contaminants. Such evaluation did not reveal the presence of microorganisms, and it was raised the possibility of antimicrobiotic activity of the raw extract in twenty three strains of bacteria and in two yeasts. According to the antimicrobial tests, the extract presented some features, as the difficult of solubility in aqueous medium, and the best dilution was achieved in dimethyl sulfoxide (DMSO) 50%. These tests also demonstrated the difficult of the solubilization of the fractions, which it will be used in the experiments of Vero cells cultures. It was verified the low antimicrobial activity of the raw hidroethanolic extract. Of all the fractions, the alkaloid fraction presented the best solubility in DMSO 0.3%. So, it was proceeded the dilution and the evaluation of the alkaloid fraction in Vero cells, and it was evaluated morphology, viability and cellular proliferation. We finally verified the citotoxicity of the alkaloid fraction in the statistical analyses, and in the vitality test carried out by Trypan blue, and also in the morphological alterations compatible to citotoxity alterations. / A espécie de jurubeba estudada no presente trabalho é Solanum scuticum M. Nee, da qual não eram disponíveis dados farmacognósticos e nem morfoanatômicos para Goiás. Para a avaliação morfoanatômica das folhas S. scuticum realizaram-se cortes à mão livre e cortes permanentes como descrito por Kraus e Arduin (1997). Para realização de triagem fitoquímica utilizou-se as metodologias descritas por Costa (2001). Com na triagem fitoquímica, foram identificados alcalóides, flavonóides cumarinas, heterosídios antraquinônicos e heterosídios saponínicos na prospecção fitoquímica. O extrato etanólico das folhas foi obtido e apartir do mesmo procedeu-se o fracionamento por diferença de polaridade, e realizaram-se avaliações dos seus componentes através de cromatografia de camada delgada. Testou-se a esterelidade da droga em pó e a possível atividade antimicrobiana do extrato bruto hidoalcoólico de S. scuticum. Tal avaliação não revelou a presença de microrganismos, sendo levantada a possível atividade antimicrobiana do extrato bruto frente a vinte e três cepas de bactérias e duas de leveduras. Os testes demonstraram também a dificuldade de solubilização das frações, as quais seriam utilizadas nos experimentos de cultura de células da linhagem Vero. Sendo averiguada baixa atividade anti-microbiana do extrato hidroalcóolico bruto. Tendo em vista as atividades biológicas do grupo dos alcalóides procedeu-se à obtenção da fração alcaloídica a partir do pó das folhas. Pelos testes antimicrobianos o extrato apresentou características de difícil solubilidade em meio aquoso, a melhor diluição para emprego do extrato foi obtida em dimetilsulfóxido (DMSO) 50%. Das frações a que possuiu melhor solubilidade em DMSO foi à alcaloídica, na concentração de 0,3%. Assim procedeu-se a diluição e a avaliação da atividade da fração alcaloídica em células da linhagem Vero, avaliando-se a morfologia, viabilidade e proliferação celular frente aos tratamentos realizados. Verificando-se atividade citotóxica da fração alcaloídica tanto nas avaliações estatísticas do teste de vitalidade por azul de Trypan, quanto nas alterações morfológicas compatíveis com alterações citotóxicas.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The turbulent fluxes of carbon dioxide (CO2 ) were investigated in two sites of irrigated rice in southern Brazil, using the eddy covariance technique over 385 days of analysis at the site of Paraiso do Sul and 683 days in site Cachoeira do Sul also used the model of filling the gaps in order to estimate the net ecosystem exchange CO2 -C (NEE). Throughout the growing season, rice fields, both for the site of Paraiso do Sul to the site of Cachoeira do Sul, acted as carbon sinks (C). During fallow periods, these fields were the source of C. The NEE accumulated at the site of Cachoeira do Sul was similar in both cycles and practically equal to the estimated site of Paraiso do Sul. The GPP accumulated during the crop cycle 2010-2011, the rice field of Cachoeira do Sul, was less than 12% of the 2011-2012 cycle and higher than 15% of the site of Paraiso do Sul. The Re accumulated was similar at the site of Paraíso do Sul in the 2010-2011 cycle Cachoeira do Sul, but less than the 2011- 2012 cycle. The values of NEE, GPP and R e for the site of Paraíso do Sul were - 270.53 gCm2 , -821.19gCm2 and 527.59gCm2 , respectively. To the site of Cachoeira do Sul, were -282,53 gCm2 , -933,40gCm2 and 597,05gCm2 for NEE, GPP and Re , respectively, in the 2010-2011 cycle. For the 2011-2012 cycle in the rice field of Cachoeira do Sul, the values of NEE, GPP and Re were -279,69gCm2 , - 1062,64gCm2 and 716,58gCm2 , respectively. The total C accumulated over the period analyzed for the site of Paraíso do Sul was -45,90gCm2 , considering this area of rice cultivation, as a sink for C. While the growing area of Cachoeira do Sul was considered a source of C (19,94 gCm2 ). Showing by this that long periods of fallow contribute significantly to the accumulated fluxes due to constant presence of vegetation. The contribution of this work will assist in the investigation of CO2 in these ecosystems. / Os fluxos turbulentos de dióxido de carbono (CO2 ) foram investigados em dois sítios de cultura de arroz irrigado no Sul do Brasil, utilizando a técnica de covariância de vórtices ao longo de 385 dias de análise no sítio de Paraíso do Sul e de 683 dias, no sítio de Cachoeira do Sul. Além disso, utilizou-se o modelo de preenchimento das lacunas com o objetivo de estimar a troca líquida de C-CO2 no ecossistema (NEE). Ao longo do período de cultivo, os campos de arroz, tanto para o sítio de Paraíso do Sul quanto para o sítio de Cachoeira do Sul, atuaram como sumidouros de carbono (C). Durante os períodos de pousio, esses campos foram fontes de C. O NEE acumulado, no sítio de Cachoeira do Sul foi semelhante em ambos os ciclos e praticamente igual ao estimado no sítio de Paraíso do Sul. A GPP acumulada durante o ciclo de cultivo de 2010-2011, no campo de arroz de Cachoeira do Sul, foi inferior a 12% do ciclo de 2011-2012 e superior em 15% a do sítio de Paraíso do Sul. A Re acumulada foi semelhante no sítio de Paraíso do Sul e no ciclo de 2010- 2011 de Cachoeira do Sul, mas inferior a do ciclo de 2011-2012. Os valores de NEE, GPP e Re para o sítio de Paraíso do Sul foram de -270,53 gCm2 , -821,19gCm2 e 527,59gCm2 , respectivamente. Para o sítio de Cachoeira do Sul, foram de - 282,53gCm2 , -933,40gCm2 e 597,05gCm2 para NEE, GPP e Re , respectivamente, no ciclo de 2010-2011. Para o ciclo de 2011-2012, no campo de arroz de Cachoeira do Sul, os valores de NEE, GPP e Re foram de -279,69gCm2 , - 1062,640gCm2 e 716,58gCm2 , respectivamente. O total de C acumulado ao longo do período analisado para o sítio de Paraíso do Sul foi de -45,90gCm2 , considerando esta área de cultivo de arroz, como um sumidouro de C. Enquanto que a área de cultivo de Cachoeira do Sul foi considerada fonte de C (19,94 gCm2 ). Mostrando com isso, que períodos longos de pousio contribuem consideravelmente para os fluxos acumulados devido a permanência constante de vegetação. A contribuição deste trabalho auxiliará na investigação das emissões de CO2 nesses ecossistemas.

<p>The global carbon cycle is subject to intense research, where sources and sinks for greenhouse gases, carbon dioxide in particular, are estimated for various systems and biomes. Lakes have previously been neglected in carbon balance estimations, but have recently been recognized to be significant net sources of CO2.</p><p>This thesis estimates emission of carbon dioxide (CO2) from boreal lakes and factors regulating the CO2 saturation from field measurements of CO2 concentration along with a number of chemical, biological and physical parameters. Concentration of dissolved organic carbon (DOC) was found to be the most important factor for CO2 saturation in lake water, whereas climatic parameters such as precipitation, temperature and global radiation were less influential. All lakes were supersaturated with and, thus, sources of CO2. Sediment incubation experiments indicated that in-lake mineralization processes during summer stratification mainly occurred in the pelagial. Approximately 10% of the CO2 emitted from the lake surface was produced in epilimnetic sediments. </p><p>The mineralization of DOC and emission of CO2 from freshwaters was calculated on a catchment basis for almost 80,000 lakes and 21 major catchments in Sweden, together with rates of sedimentation in lakes and export of organic carbon to the sea. The total export of terrestrial organic carbon to freshwaters could thereby be estimated and consequently also the importance of lakes for the withdrawal of organic carbon export from terrestrial sources to the sea. Lakes removed 30-80% of imported terrestrial organic carbon, and mineralization and CO2 emission were much more important than sedimentation of carbon. The carbon loss was closely related to water retention time, where catchments with short residence times (<1 year) had low carbon retentions, whereas in catchments with long residence times (>3 years) a majority of the imported TOC was removed in the lake systems. </p><p>The Gulf of Bothnia was also studied in this thesis and found to be a net heterotrophic system, emitting large amounts of CO2 to the atmosphere on an annual basis. The rate of CO2 emission was depending on the balance between primary production and bacterial respiration, and the system was oscillating between being a source and a sink of CO2.</p>

The global carbon cycle is subject to intense research, where sources and sinks for greenhouse gases, carbon dioxide in particular, are estimated for various systems and biomes. Lakes have previously been neglected in carbon balance estimations, but have recently been recognized to be significant net sources of CO2. This thesis estimates emission of carbon dioxide (CO2) from boreal lakes and factors regulating the CO2 saturation from field measurements of CO2 concentration along with a number of chemical, biological and physical parameters. Concentration of dissolved organic carbon (DOC) was found to be the most important factor for CO2 saturation in lake water, whereas climatic parameters such as precipitation, temperature and global radiation were less influential. All lakes were supersaturated with and, thus, sources of CO2. Sediment incubation experiments indicated that in-lake mineralization processes during summer stratification mainly occurred in the pelagial. Approximately 10% of the CO2 emitted from the lake surface was produced in epilimnetic sediments. The mineralization of DOC and emission of CO2 from freshwaters was calculated on a catchment basis for almost 80,000 lakes and 21 major catchments in Sweden, together with rates of sedimentation in lakes and export of organic carbon to the sea. The total export of terrestrial organic carbon to freshwaters could thereby be estimated and consequently also the importance of lakes for the withdrawal of organic carbon export from terrestrial sources to the sea. Lakes removed 30-80% of imported terrestrial organic carbon, and mineralization and CO2 emission were much more important than sedimentation of carbon. The carbon loss was closely related to water retention time, where catchments with short residence times (&lt;1 year) had low carbon retentions, whereas in catchments with long residence times (&gt;3 years) a majority of the imported TOC was removed in the lake systems. The Gulf of Bothnia was also studied in this thesis and found to be a net heterotrophic system, emitting large amounts of CO2 to the atmosphere on an annual basis. The rate of CO2 emission was depending on the balance between primary production and bacterial respiration, and the system was oscillating between being a source and a sink of CO2.