Dissolved organic carbon (DOC) is a sum parameter that is frequently used in water analytics. Highly resolved and accurate DOC data are necessary, for instance, for water quality monitoring and for the evaluation of the efficiency of treatment processes. The conventional DOC determination methods consist of on-site sampling and subsequent analysis in a stationary device in a laboratory. However, especially in regions where no or only poorly equipped laboratories are available, this method bears the risk of getting erroneous results. For this reason, the objective of the present study was to set up a reliable and portable DOC analyzer for on-site analysis. The presented DOC system is equipped with an electrolysis-based decomposition cell with boron-doped diamond electrodes (BDD) that oxidizes the organic compounds to carbon dioxide. Within this study, the influence of different electrode materials and the composition of the applied electrolytes on the DOC decomposition in an undivided electrolytic cell were systematically investigated. Furthermore, some technical aspects of the portable prototype are discussed. After a detailed validation, the prototype was used in an ongoing monitoring program in Northern India. The limit of detection is 0.1 mg L−1 C with a relative standard deviation of 2.3% in a linear range up to 1000 mg L C−1. The key features of the portable DOC analyzer are: No need for ultra-pure gases, catalysts or burning technology, an analyzing time per sample below 5 min, and a reliable on-site DOC determination.

Diploma thesis is focused on changes of organic carbon (OC) in surface waters in headwater areas. Thesis is in its theoretical part focused on the literature study of currently published research results of the issue. The important part is finding the possible causes of OC variability, especially landcover and soil environment. The practical part is devoted to research in experimental basins of KFGG, namely in the upper Vydra, Blanice and Rolava. The aim of this work is to clarify the relationships between organic matter concentrations and discharge rates regarding to hydrological extremes. Furthermore, the influence of river basin size and various landcover and variability of concentrations and relationship with other indicators of biogeochemism is studied. The relationship between OC and discharge rate is positive and in most river basins strong or very strong. The weakest relationship was monitored on the profiles with the highest proportion of peatlands in the river basin. In these catchments, the highest average concentrations of OC were determined in autumn, in catchments with the lower proportion of peatlands it is in summer. Analysis of rainfall-runoff events confirmed the positive relationship of OC and discharge. The lag time of the maximum OC concentration beyond the maximum discharge...

Die Schriftenreihe informiert über Forschungsergebnisse zur Entstehung und Transport von gelösten organischen Kohlenstoffverbindungen (DOC, dissolved organic carbon) im Einzugsgebiet der Talsperre Sosa. DOC entsteht in den Humusauflagen der Wälder, in degradierten Mooren und in mineralischen Böden. Es wird insbesondere bei Starkregen und während der Schneeschmelze ausgetragen. Der Eintrag in die Gewässer hängt ab von der Freisetzung des DOC, von der Fließverbindung des Bodenwassers und von Rückhalteprozessen im Boden. Hieraus ergeben sich mögliche Optionen zur Verminderung des DOC-Eintrags in Trinkwassertalsperren, da DOC hier erhebliche Probleme verursacht. Die Veröffentlichung richtet sich an Forschungseinrichtungen, Fach- und Vollzugsbehörden und interessierte Bürgerinnen und Bürger. Redaktionsschluss: 30.09.2023

During recent decades many lakes have become browner in the northern hemisphere and more specific in Sweden. This process is called brownification. Brownification of lakes makes it more difficult to clean water to drinking water and may have negative ecological effects on biota. Browning of lakes is generally thought to be caused by an increase of humic substances that consist of organic matter which colour the water brown or yellow. However, more recent studies show that dissolved iron can interact with humic substances in browning lakes. Since the concentrations of dissolved iron have increased during recent years and the mechanisms behind brownification and the contribution of iron to this process is not clearly understood it is important to investigate this subject. In this study 17 lakes in south of Sweden were sampled for iron concentration, dissolved organic carbon (DOC), absorbance (420nm) and pH. Further, data was added about atmospheric sulphur deposition and additional data from 17 lakes in the north part of Sweden. Iron had a stronger significant correlation towards absorbance than DOC had in the south of Sweden. A similar amount of dissolved iron seems to colour lakes differently based on their location in Sweden. This indicates that different mechanisms are involved in the interaction between iron and absorbance. However, pH had a stronger relationship with absorbance than either DOC or iron. Overall results suggested that iron do have a strong browning effect on Swedish fresh water lakes in the presence of DOC and that iron-increase driven processes may be due to a change of pH.

Submitted by Verena Bastos (verena@uefs.br) on 2015-07-24T13:10:21Z No. of bitstreams: 1 Disserta??o Vers?o Final PPGE.pdf: 1710934 bytes, checksum: 605e366486bf44504246bf954e460d18 (MD5) / Made available in DSpace on 2015-07-24T13:10:21Z (GMT). No. of bitstreams: 1 Disserta??o Vers?o Final PPGE.pdf: 1710934 bytes, checksum: 605e366486bf44504246bf954e460d18 (MD5) Previous issue date: 2014-03-11 / Dissertative this work, developed in the Graduate Program in Education , State University of Feira de Santana - Bahia , we analyze , from the representations of teachers participating in the experience of teacher training : teaching and learning , Learning and Evaluation in Higher Education , the changes occurring in their educational practice . Initially , we present the scenario of expansion of higher education , the legal basis of performance and training needs of university professors . We then describe some experiences of teacher training and present a review of literature on the production of dissertations and theses from CAPES , in order to understand the advances in research on university teaching and possible gaps . In Theoretical Framework , we point briefly , the political landscape of teacher education in Brazil , the context of university teaching and the relationship between teacher identity and professionalism to then describe some models of teacher training ( education model based on analysis practices and reflection , education model for methodological work or didactic work , Model inquiring or research training and continuing education model for didactic- pedagogic update) . The research methodology is based on the principles of the Social Representations Theory ( SRT) , characterized as a descriptive, qualitative character. The research group was composed of 06 faculty members who participated UEFS the last class of the course mentioned above , and a teacher trainer . The procedure of collecting and compiling the data used was the semistructured interview and the chosen method of analysis , thematic analysis of Bardin (1977 ) . In the presentation and discussion of the data , 03 categories were identified : the first related to participating teachers ( teacher identity , teacher training and training needs ) ; The second , related to the course ( origin, epistemological concept , teaching strategies , encouraging the institution , difficulties and setbacks ) ; and third , the ongoing contributions to pedagogical practice ( socialization among teachers in student learning , the innovative experiments in the evaluation process and the weaknesses and suggestions made by teachers ) . In the conclusion , we list some aspects that denote the importance of this training experience , including : epistemological reflections of teachers on their practices , innovations in teaching strategies , personal and professional growth, to improve the academic activities and better understanding of act of teaching and learning. / Neste trabalho dissertativo, desenvolvido no Programa de P?s-Gradua??o em Educa??o da Universidade Estadual de Feira de Santana ? Bahia, buscamos analisar, a partir das representa??es dos professores participantes da experi?ncia de forma??o pedag?gica: Ensinagem, Aprendizagem e Avalia??o no Ensino Superior, as mudan?as ocorridas em sua pr?tica educativa. Inicialmente, apresentamos o cen?rio de expans?o do ensino superior, as bases legais de atua??o e as necessidades formativas de professores universit?rios. Em seguida, descrevemos algumas experi?ncias de forma??o pedag?gica e apresentamos uma revis?o de literatura sobre as produ??es de disserta??es e teses da CAPES, a fim de compreendermos os avan?os das pesquisas sobre a doc?ncia universit?ria e as poss?veis lacunas existentes. No Quadro Te?rico, pontuamos, de forma breve, o cen?rio pol?tico da forma??o de professores no Brasil, o contexto da doc?ncia universit?ria e a rela??o entre identidade docente e profissionaliza??o para, em seguida, descrevermos alguns modelos de forma??o pedag?gica (Modelo de forma??o baseada na an?lise das pr?ticas e na reflex?o, Modelo de forma??o por trabalho metodol?gico ou trabalho did?tico, Modelo de forma??o indagativo ou de pesquisa e Modelo de forma??o continuada por atualiza??o did?tico-pedag?gica). A metodologia da pesquisa est? fundamentada nos princ?pios da Teoria das Representa??es Sociais (TRS), caracterizando-se como uma pesquisa descritiva, de car?ter qualitativo. O grupo pesquisado foi constitu?do de 06 docentes da UEFS que participaram da ?ltima turma do curso anteriormente referido e um professor formador. O procedimento de coleta e produ??o dos dados utilizados foi a entrevista semiestruturada e o m?todo de an?lise escolhido, a An?lise Tem?tica de Bardin (1977). Na apresenta??o e discuss?o dos dados, foram identificadas 03 categorias: a primeira, relacionada aos professores participantes (identidade docente, forma??o pedag?gica e necessidades formativas); a segunda, referente ao curso (origem, concep??o epistemol?gica, estrat?gias de ensino, o incentivo da institui??o, dificuldades e contratempos); e a terceira, contribui??es do curso para a pr?tica pedag?gica (na socializa??o entre professores, no aprendizado dos estudantes, nas experi?ncias inovadoras, no processo avaliativo e nas fragilidades e sugest?es apontadas pelos professores). Nas considera??es finais, elencamos alguns aspectos que denotam a import?ncia dessa experi?ncia de forma??o, dentre eles: a reflex?o epistemol?gica dos docentes sobre suas pr?ticas, as inova??es nas estrat?gias de ensino, o crescimento pessoal e profissional, a melhoria das atividades acad?micas e a melhor compreens?o do ato de ensinar e aprender.

Os compostos (coloidais, suspensos e solúveis) presentes na água residual possuem diferentes características físico-químicas e diferentes massas moleculares. Pesquisadores têm se dedicado ao entendimento mais específico da parte solúvel do efluente. O fracionamento das substâncias orgânicas em diferentes classes e diferentes tamanhos é um dos métodos utilizados para a caracterização dos compostos orgânicos da água residual. Acredita-se que este método possa detectar as alterações nos valores residuais dos compostos orgânicos de forma mais precisa que os métodos tradicionais, i.e. DBO e DQO. Sendo assim, e sabendo do crescente uso dos projetos de pós-tratamento dos efluentes de ETE e reúso destes, fica a clara a avaliação da eficiência dos processos de pós-tratamento e a importância da quantificação e caracterização da matéria orgânica residual no efluente pós-tratado. Os objetivos deste projeto de pesquisa foram avaliar a remoção da carga orgânica residual no efluente do tratamento biológico do processo de lodo ativado da ETE Jesus Netto, utilizando diferentes parâmetros de coagulação/floculação utilizando cloreto férrico, sulfato de alumínio e cloreto de polialumínio como coagulantes, e análise de carbono orgânico dissolvido juntamente com a técnica de distribuição da massa molecular para avaliar essa remoção. As análises mostraram uma redução dos compostos orgânicos presentes no efluente secundário, em termos de carbono orgânico dissolvido, da ordem de 45% para o cloreto férrico e 38% para os sais de alumínio. A distribuição da massa molecular também sofreu alterações, notando-se o aumento dos compostos de menor massa molecular e a redução dos compostos de maior massa molecular. Os resultados corroboram com outros estudos realizados com efluentes secundários e águas de abastecimento sobre o impacto dos processos físico-químicos na distribuição da massa molecular. / The compounds (colloidal, suspended and soluble) present in the waste water have different physicochemical characteristics and different molecular masses. Researchers have dedicated themselves to the more specific understanding of the soluble part of the effluent. The fractionation of the organic substances in different classes and different sizes is a method widely used for the characterization of the organic compounds of the residual water. It´s believed that this method can detect changes of organic compounds residual values more accurately than traditional methods, i.e. biological oxygen demand and chemical oxygen demand. Therefore, knowing the increasing use of WWTP effluent after post-treatment processes and their reuse, it is clear that the evaluation of the post-treatment efficiency and the importance of the quantification and characterization of the residual organic matter in the post-treated effluent. The objectives of this research project were to evaluate the removal of the residual organic matter in the effluent from the biological treatment of the activated sludge process of the Jesus Netto WWTP using different coagulation/flocculation parameters with ferric chloride, aluminium sulfate and polyaluminum chloride (PAC) as coagulants, and dissolved organic carbon and molecular mass distribution analyses to evaluate the organic matter removal. The analyzes showed a reduction of the organic matter present in the secondary effluent, in terms of dissolved organic carbon, up to 45% for ferric chloride and 38% for aluminum salts. The distribution of the molecular mass also changed, with the increase of the compounds of lower molecular mass and the reduction of the compounds of higher molecular mass. The results corroborate with other studies carried out with secondary effluents and water supply on the impact of physicochemical processes on the molecular weight distribution.

Made available in DSpace on 2016-04-28T20:13:49Z (GMT). No. of bitstreams: 1 2008 - Lia Maria Teixeira de Oliveira.pdf: 1251999 bytes, checksum: e5651642f1d88ff158a2af934701acb6 (MD5) Previous issue date: 2008-05-30 / The main concerning of this thesis has been about social identities accomplishment, understanding them as a relational and multidimensional process performed through successive socialization. In relation to specific theme, this survey was carried out under socialization methodologies of agricultural technical teaching professor at the time of educational politics start on the 90 s, concerning about the management model restoring and technological institution working as well as professor professionalization conception. However, data from field research forced to an analysis motion giving rise to professional establishment, when around 1910 to 1940, and republican public announcement for the professionalization of an education able to interfere over poor young people, useful citizens professional teaching have emerged on society. Verifying global significatives of official system as competence ideas and education, an approachment was limited on, in spite of notifying over local contexts and resistances no consensus or ordinary readings on the global significatives were reported. Through field research and bibliographic references institutional space-time existence pointed by permanences and ambiguities have been demonstrated when at currents days these signs from past ages and structural duality under school/university sphere pressurize sociocultural methods towards actions and emancipated character perception from hegemonic agrarian commands. Theorical discussion was based on political and cultural spaces understanding that on society both groups and people have been shaped in relation to knowledgements, values, behaviors and profiles for playing a role on every professional occupation or another professional area. In order to represent not as much balanced reality about determinations and permanences relationships under the same stress to and for teaching professionalization dispute has been corroborate. In this meaning, the main goal of the survey was to understand agricultural technical teaching professor identities from social professional process institutionalized by political and academic socialization aspect. Above all, it was considered this sphere as a conflict place, specially crossed by outter and inner as well as subjective and objective spheres to professional groups. According to Pierre Bourdieu, Berger and Luckmam, Anthony Giddens, Gimeno Sacrist?n, Claude Dubar, Eliot Freidson on ANFOPE and ANPED speechs, data and information approachment / interpretation were based on. As maintained by Eli Lima, An?sio Teixeira, S?rgio Miceli and Renato Ortiz ideas nation and culture studies, institutional scheme played by actors / agents was demonstrated. In relation to political, economical and cultural practices of contemporary societies, theories by Roberto Jose Moreira were reported. The methodology of this survey has been based on human and social sciences qualitative research where proceedings and mechanisms from ethnographic nature have noticed professor occupation as a social performance on ruptures methods with ancient patterns, therefore a professional-social group represented by tensions caused between permanencies and ambiguities over a relational reality in accordance to dynamics of new institutionalization practices. / A problem?tica central dessa tese ? o estudo sobre a constru??o social do magist?rio, cuja an?lise compreende as identidades docentes como processo multidimensional e relacional produzido nas sucessivas socializa??es. Quanto ? tem?tica espec?fica, no tocante ? pesquisa geradora dessa tese refere-se aos processos de socializa??o do professor do ensino t?cnico agr?cola, no marco temporal da pol?tica educacional iniciada na d?cada de 1990, cuja t?nica ? a reestrutura??o do modelo de gest?o e funcionamento da institui??o tecnol?gica e a concep??o de profissionaliza??o docente. Contudo os dados da pesquisa de campo for?aram um deslocamento da an?lise para a origem da constitui??o profissional, quando por volta dos anos de 1910 at? 1940 incidem na sociedade os proclames p?blicos republicanos para a profissionaliza??o de um magist?rio capaz de uma interven??o qualificada na educa??o profissional dos jovens desvalidos para serem cidad?os ?teis . Delimita-se ainda um enfoque de profiss?o docente, verificando os significantes globais vindos do sistema oficial, como a no??o de compet?ncias, mas a licenciatura nos contextos locais demonstra n?o haver consensos sobre tais significantes globais. Congruente ao saberfazer docente e aos processos identit?rios profissionais, demonstra-se por meio do trabalho de pesquisa de campo, documentos e da literatura, a exist?ncia de espa?os/tempos institucionais marcados pelas perman?ncias e ambig?idades, contudo na atualidade, essas marcas do passado e da dualidade estrutural sob a esfera escolar/universit?ria tencionam os processos socioculturais e acad?micos para a??es e percep??es de car?ter mais emancipado dos dom?nios agr?rios hegem?nicos. A discuss?o te?rica que atravessa toda a tese remete ao entendimento que em sociedade, nos espa?os pol?tico-culturais, os indiv?duos e grupos s?o moldados por saberes, atitudes, valores, normaliza??o t?cnica e perfis para exercerem pap?is na profiss?o docente ou em outra ?rea profissional. De modo a configurar uma realidade n?o t?o equilibrada em rela??es de perman?ncias e determina??es, verifica-se a mesma sob tens?o na e pela disputa de profissionaliza??o docente. Neste sentido, o objetivo geral da tese ? buscar compreender as identidades docentes desse professor da educa??o t?cnica agr?cola a partir dos processos s?cio-profissionais institucionalizados pelo campo pol?tico-acad?mico de socializa??o. Sobretudo, tomamos esse espa?o como um lugar de disputas, particularmente, eivado de articula??es/intera??es das esferas interiores e exteriores, subjetivas e objetivas ao grupo profissional. A abordagem e a interpreta??o dos dados e informa??es coletadas da pesquisa de campo delimitam-se na revis?o de literatura tomada nas categorias da sociologia compreensiva de Pierre Bourdieu, Berger e Luckmann, Anthony Giddens, tamb?m na sociologia da educa??o de Gimeno Sacrist?n, na sociologia das profiss?es de Claude Dubar, Eliot Freidson e diversos te?ricos e pesquisadores referenciados no discurso da ANFOPE e ANPED. Demonstra-se o enredamento institucional promovido entre os atores/agentes que organizam os estudos das id?ias, na??o e cultura, nesse caso destaque-se Eli Lima, An?sio Teixeira, S?rgio Miceli, Renato Ortiz. ?s teorias das sociedades contempor?neas no tocante as pr?ticas pol?ticas, econ?micas e culturais que configuram e conferem significados ao campo brasileiro, busca-se em Roberto Moreira. A metodologia est? balizada nos aportes te?ricos da pesquisa qualitativa em ci?ncias sociais e humanas, aonde os procedimentos e instrumentos de natureza etnogr?fica chegaram aos dados que constata ser a profiss?o docente uma constru??o social em processos de rupturas com os modelos passados, portanto, um grupo s?cio-profissional configurado nas tens?es provocadas entre as perman?ncias e ambig?idades sobre uma realidade relacional, em plena din?mica de novos processos de institucionaliza??o.

Submitted by Sara Ribeiro (sara.ribeiro@ucb.br) on 2017-06-01T20:37:38Z No. of bitstreams: 1 LeidianeAlmeidaAraujoDissertacaoParcial2015.pdf: 800016 bytes, checksum: 02dcab50ff82696b5d6903b0d2dac9df (MD5) / Approved for entry into archive by Sara Ribeiro (sara.ribeiro@ucb.br) on 2017-06-01T20:37:59Z (GMT) No. of bitstreams: 1 LeidianeAlmeidaAraujoDissertacaoParcial2015.pdf: 800016 bytes, checksum: 02dcab50ff82696b5d6903b0d2dac9df (MD5) / Made available in DSpace on 2017-06-01T20:37:59Z (GMT). No. of bitstreams: 1 LeidianeAlmeidaAraujoDissertacaoParcial2015.pdf: 800016 bytes, checksum: 02dcab50ff82696b5d6903b0d2dac9df (MD5) Previous issue date: 2015-12-04 / It was proposed in the present study to investigate the relationship between perceptions of teacher self-efficacy and social emotional support of graduating students of pedagogy and beginner teachers in early childhood education or in the early years of elementary school. The teaching self-efficacy refers to the teacher's confidence in their own abilities to perform teaching activities associated with perceived social support that can help the adaptation of the individual during the transition to teaching. It is understood that this transition is not finished with the completion of graduation, it extends until the first years of teaching practice. The total sample consisted of 281 participants. The scale was composed of three parts: [1] Teacher Beliefs Scale - short version, [2] Inventory of Emotional Support in the Transition to Teaching (IAETD) and [3] Participants Characterization Questionnaire. The results obtained by means of confirmatory factor analysis indicated evidence of instrument validity and good internal consistency in the factors. The better adjusted models presented the teacher's self-efficacy in three factors: efficacy in instructional strategies (EIS) effectiveness in managing classroom (EMC) and efficacy in student engagement (ESA); the social and emotional support to two factors: emotional support and professional support. It was found that training in public or private institutions does not imply distinctions in perceptions of the teacher self-efficacy and the social emotional support for both groups. However, when related to sex, women had greater efficacy in student engagement than men in both groups. Among teachers, those without postgraduate degrees demonstrated higher self-efficacy to motivate students than teachers with postgraduate degrees. Teachers with plans to stay in teaching careers felt themselves more professionally supported than those with plans to switch careers. It was also found that the older the teachers, the lower the self-efficacy for managing the classroom and lower the perception of professional support. In the group of students, the ones who were working were perceived to be more effective in managing the classroom than students that were not working. Finally, the weak relationships between the variables of teacher self-efficacy and social emotional support in both groups reinforced the prospects of the multidimensionality of these phenomena, indicating that other factors are combined in this relationship in the transition to teaching. Along these lines, new studies can address the dynamics and direction of these relationships in the development of teachers. / Prop??s-se, neste estudo, verificar a rela????o entre as percep????es de autoefic??cia docente e apoio social emocional de estudantes concluintes do Curso de Pedagogia e professores iniciantes na Educa????o Infantil ou nos anos iniciais do Ensino Fundamental. A autoefic??cia docente refere-se ?? confian??a do professor em suas pr??prias capacidades para desempenhar atividades docentes que associada ?? percep????o de apoio social pode favorecer a adapta????o do indiv??duo durante a transi????o para a doc??ncia. Entende-se que essa transi????o n??o ?? finalizada com a conclus??o da Gradua????o, porque ela se estende at?? os primeiros anos de atua????o docente. A amostra total foi de 281 participantes. O instrumento foi composto por tr??s partes: [1] Escala de Cren??as Docentes ??? vers??o curta, [2] Invent??rio de Apoio Emocional na Transi????o para a Doc??ncia (IAETD) e [3] Question??rio de Caracteriza????o dos Participantes. Os resultados obtidos por meio das an??lises fatoriais confirmat??rias indicaram evid??ncias de validade do instrumento e boa consist??ncia interna dos fatores. Os modelos mais ajustados apresentaram a autoefic??cia docente com tr??s fatores: efic??cia nas estrat??gias instrucionais (EEI), efic??cia no manejo em sala de aula (EMSA) e efic??cia no engajamento do aluno (EEA); e o apoio social emocional com dois fatores: apoio afetivo e apoio profissional. Verificou-se que a forma????o em institui????es p??blicas ou privadas n??o implica em distin????es nas percep????es de autoefic??cia docente e apoio social emocional para ambos os grupos. No entanto, quando relacionadas ao sexo, as mulheres apresentaram maior efic??cia no engajamento dos alunos que os homens de ambos os grupos. Entre os professores, aqueles sem P??s-Gradua????o demonstraram maior autoefic??cia para motivar os alunos que os professores com P??s-Gradua????o. Os professores com planos de permanecer na doc??ncia perceberam-se mais apoiados profissionalmente que aqueles com planos de mudar de profiss??o. Verificou-se tamb??m que quanto maior a idade dos professores menor a autoefic??cia para o manejo de sala de aula e menor a percep????o de apoio profissional. No grupo de estudantes, os que estavam trabalhando perceberam-se mais eficazes no manejo da sala de aula que os estudantes n??o trabalhadores. Por fim, as fracas rela????es entre as vari??veis de autoefic??cia docente e apoio social emocional em ambos os grupos refor??aram as perspectivas da multidimensionalidade desses fen??menos, sinalizando que outros fatores coadunam nessa rela????o durante a transi????o para a doc??ncia. Nessa linha, novos estudos podem abordar a din??mica e o sentido dessas rela????es no desenvolvimento do docente.

<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>

Many Canadian water treatment plants supplied by surface waters of the Canadian Prairie and Shield have elevated concentrations of trihalomethanes (THMs), which exceed the provincial standards. These water sources are characterized by elevated levels of dissolved organic carbon (DOC) and varying levels of calcium hardness, which causes a challenge for the removal of THMs precursors. The objective of this study was to investigate the effect of two treatment methods: chemical coagulation and pre-ozonation-coagulation on the removal of DOC as the main THMs precursor. Surface waters typical for the Canadian Prairie and Canadian Shield were used in the experiments which includes Assiniboine River, Red River, and Rainy River. The effects of different experimental conditions such as coagulant dose, coagulant type, and solution pH as well as ozone dosage on THMs removal were investigated. The structural and chemical characteristics of natural organic matter and isolated humic substances, before and after the reaction with ozone, were studied using spectroscopic techniques. The results illustrated that the quality of source water (DOC characteristics, concentration of water DOC and Calcium) has a significant impact on THMs reduction by chemical coagulation and ozonation. Coagulation results showed that reduction of total DOC does not guarantee THMFP reduction and chemical coagulation should be optimized to remove the hydrophobic acid fraction which forms most THMs. The removal of DOC by aluminum-based coagulants was affected more by the concentration of polymeric and colloidal aluminum speciation. This finding is especially important for plants supplied by high alkalinity waters where pH adjustment is a serious challenge. The effect of pre-ozonation on coagulation varies depending on the concentration of calcium, which has the ability to form complexes with DOC compounds promoting their removal in coagulation. For the surface water with high levels of organic carbon and calcium hardness, ozonation prior to coagulation was beneficial in terms of DOC reduction. However, it showed the opposite effect on water with high levels of DOC accompanied with low level of calcium hardness. Spectroscopic results showed that ozonation of NOM and humic substances cause a significant reduction of aromatic and highly conjugated compounds (constituting primarily the hydrophobic acid fraction). / February 2016