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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
701

Trade-offs in Utilizing of Zero-Valent Iron for Synergistic Biotic and Abiotic Reduction of Trichloroethene and Perchlorate in Soil and Groundwater

January 2017 (has links)
abstract: The advantages and challenges of combining zero-valent iron (ZVI) and microbial reduction of trichloroethene (TCE) and perchlorate (ClO4-) in contaminated soil and groundwater are not well understood. The objective of this work was to identify the benefits and limitations of simultaneous application of ZVI and bioaugmentation for detoxification of TCE and ClO4- using conditions relevant to a specific contaminated site. We studied conditions representing a ZVI-injection zone and a downstream zone influenced Fe (II) produced, for simultaneous ZVI and microbial reductive dechlorination applications using bench scale semi-batch microcosm experiments. 16.5 g L-1 ZVI effectively reduced TCE to ethene and ethane but ClO4- was barely reduced. Microbial reductive dechlorination was limited by both ZVI as well as Fe (II) derived from oxidation of ZVI. In the case of TCE, rapid abiotic TCE reduction made the TCE unavailable for the dechlorinating bacteria. In the case of perchlorate, ZVI inhibited the indigenous perchlorate-reducing bacteria present in the soil and groundwater. Further, H2 generated by ZVI reactions stimulated competing microbial processes like sulfate reduction and methanogenesis. In the microcosms representing the ZVI downstream zone (Fe (II) only), we detected accumulation of cis-dichloroethene (cis-DCE) and vinyl chloride (VC) after 56 days. Some ethene also formed under these conditions. In the absence of ZVI or Fe (II), we detected complete TCE dechlorination to ethene and faster rates of ClO4- reduction. The results illustrate potential limitations of combining ZVI with microbial reduction of chlorinated compounds and show the potential that each technology has when applied separately. / Dissertation/Thesis / Masters Thesis Civil, Environmental and Sustainable Engineering 2017
702

Traveling Monastic Paths: Mobility and Religion in Medieval Ireland at Five Early and Late Medieval Irish Monasteries

January 2018 (has links)
abstract: Mobility is an important aspect of the lives of religious individuals described by medieval texts in early and late medieval Ireland, and biogeochemical methods can be used to detect mobility in archaeological populations. Stories are recorded of monks and nuns traveling and founding monasteries across Ireland, Scotland, England, Wales, and other areas of Europe. However, these texts rarely address the quotidian lives of average monks and nuns who lived in monastic communities. This dissertation seeks to understand if travel was a typical part of the experiences of religious and lay people in early and late medieval Ireland. It also aims to increase understanding of how monastic communities related to the local lay communities, including addressing if the monastery was populated by those who grew up in the local area. Another methodological aim of this dissertation is to advance the field of archaeological biogeochemistry by (1) adding to the bioavailable strontium baseline in Ireland and (2) quantifying the contribution of ocean-derived strontium to coastal environments. These topics are explored through the biogeochemical analysis of 88 individuals buried at 5 early and late medieval monasteries in Ireland and the analysis of a total of 85 plant samples from four counties in Ireland. The three papers in this dissertation present: (1) a summary of the mobility of religious and lay people buried at the monasteries (Chapter 2), (2) a case study presenting evidence for fosterage of a local child at the early medieval monastery of Illaunloughan, Co. Kerry (Chapter 3), and (3) a study designed to quantify the impact of sea spray on bioavailable strontium in coastal environments (Chapter 4). The majority of lay and religious individuals studied were estimated to be local, indicating that medieval Irish Christianity was strongly rooted in the local community. The study of ocean-derived strontium in a coastal environment indicates that sea spray has a non-uniform impact on bioavailable strontium in coastal regions. These findings shed new light on medieval monastic and lay life in Ireland through the application of biogeochemical methods, contributing to the growth of the field of archaeological chemistry in Ireland. / Dissertation/Thesis / Doctoral Dissertation Anthropology 2018
703

Réponses des grands lacs périalpins aux pressions anthropiques et climatiques récentes : reconstitutions spatio-temporelles à partir d'archives sédimentaires / Responses of great perialpin lakes to recent anthropogenic and climatic forcings : spatio-temporal reconstructions from sediment archives

Jenny, Jean-Philippe 21 June 2013 (has links)
Les travaux de recherche développés durant cette thèse relèvent de la biogéochimie et de la sédimentologie appliquée aux systèmes lacustres. Ils s'inscrivent dans une démarche de rétro-observation sur la période récente (150-300 ans) avec l'objectif global d'évaluer l'implication des forçages environnementaux locaux (charge externe en nutriments, hydrologie) dans l'accentuation/atténuation des forçages globaux (climat). Nos recherches se sont concentrées sur une réponse intégratrice du système lacustre : le développement de l'état de l'hypoxie (manque d'oxygène ; [O2] <2µg L-1) dans les lacs, qui reflète l'état du système lacustre à l'échelle de l'hypolimnion. La thèse participe à un programme pluridisciplinaire, IPERRETRO ANR VMCS 008, dont les résultats sont utilisés dans ce travail pour comparer les trajectoires de 3 réponses biologiques (diatomées, cladocères, chironomes) et de la réponse de l'hypoxie dans les lacs du Léman, du Bourget et d'Annecy. Les objectifs spécifiques de ce travail de doctorat sont 1) de développer une méthode de quantification du régime de l'hypoxie au travers d'une approche spatio-temporelle (multi-site de carottage), 2) de caractériser les forçages et, 3) de recourir aux outils de modélisation statistique afin de comprendre les relations entre les forçages (globaux et locaux) et les réponses de l'écosystème lacustre dans un contexte de réchauffement climatique. Le prélèvement inédit de 81 carottes sédimentaires s'est révélé essentiel pour quantifier 2 forçages clés de l'hypoxie dans les 3 lacs : 1) les flux biogéniques et 2) le régime des crues. Nos principaux résultats montrent que l'enrichissement en phosphore dissous a conduit à un changement d'état de l'hypolimnion dès le milieu du XXe siècle. Désormais hypoxique, les écosystèmes de l'hypolimnion semblent particulièrement vulnérables face à l'augmentation croissante des températures. En revanche, l'action des crues (à l'échelle pluriannuelle, pluri-décennale et centennale) présente des effets bénéfiques sur les conditions de l'hypolimnion en favorisant périodiquement la recharge en oxygène, malgré l'état de stabilité global de l'hypoxie. D'autre part, les résultats montrent que le contexte hydrique local (~dimension des affluents) conditionne la vulnérabilité spécifique des lacs face aux changements globaux. Nous montrons qu'un lac comme Annecy (petit affluent) est plus vulnérable aux augmentations de température qu'un lac comme le Léman (gros affluent). Finalement, les trajectoires des réponses lacustres (flux biogéniques, diversité biologique et régime de l'hypoxie) indiquent que les réponses sont généralement plus immédiates dans l'hypolimnion face aux changements globaux et locaux que dans l'épilimnion. Cette différence de sensibilité des réponses, entre les « sous-systèmes », précise l'ampleur des défis pour la modélisation et la gestion intégrée des systèmes lacustres. / This Thesis is dedicated to the identification of issues (local and global stressors) that affected lakes physical and biogeological environment over the last 150 years through sediment-based palaeo-reconstructions. Our researches focussed on the recent development of hypoxia (i.e. low oxygen concentrations) which is a good indicator of lake ecosystem quality at the hypolimnetic scale. The aim is to reconstruct in 3 perialpin lakes (Geneva, Bourget, Annecy), with annual resolution, the evolution of 1) trophic level (Anthropic forcing), 2) flood regime (climate forcing) and 3) hypoxia (hypolimnetic response) in order to identify over time the role of human activity and climate on the lake ecosystem quality. A 4D approach is developed, using 80 sediment cores, to quantify for the first time the low oxygen dynamic and the flood regime from sediment archives. Statistical modelling is used to identify the relation between thermal, hydrological, trophic forcings on the response of hypoxia. 3D modelling is developed to support the results and to make results more understandable to actors of management. The principal findings gather around three topics: 1) Optimisation of spatio-temporal approach to quantify palaeoreconstruction from sediment archives based on volume calculation. Those reconstructions of hypoxia dynamic for the three lakes enable to emphasis the notion of weaken equilibrium, ecosystems vulnerability and the amplification of response following cumulative pressures. 2) New description of hypolimnetic functioning under constant increase of external pressures (with a focus on the nature of transitions between states: threshold effect, saturation effect, hypersteresis). 3) The contribution of palaeoreconstructions and statistical analyses to describe the respective influence of human activity and climate involved on the initiation of lake dysfunction, maintain or rebalancing of hypolimnetic functioning.
704

Processos hidrobiogeoquímicos de carbono e nitrogênio em diferentes usos da terra nas mesobacias dos rios Jaguari e Camanducaia / Hydrobiogeochemical processes of carbon and nitrogen in different land uses in the Jaguari and Camanducaia rivers watershed

Cristiane Formigosa Gadelha da Costa 12 January 2018 (has links)
O objetivo deste estudo foi compreender o efeito das mudanças no uso da terra na distribuição e transporte de carbono e nitrogênio, em rios de diferentes ordens nas bacias hidrográficas dos rios Jaguari e Camanducaia. O rio Jaguari tem o rio Camanduacia como um dos seus principais afluentes, e é um importante supridor do sistema de reservatórios \"Cantareira\", que abastece cerca de seis milhões de habitantes da Região Metropolitana de São Paulo, Brasil. Em cada sub-bacia, iniciou-se em janeiro de 2015 um estudo de um ano hidrológico, para monitoramento de parâmetros de qualidade da água, como pH, condutividade elétrica (CE), oxigênio dissolvido e porcentagem (OD), carbono orgânico e inorgânico dissolvido (DOC e DIC), nitrato (NO3-), amônio (NH4+), nitrito (NO2-), nitrogênio orgânico (NOD), nitrogênio total (TN), temperatura do ar e da água (T °C) e vazão (Q) para monitoramento do ambiente, além de taxa de respiração (TR), demanda bioquímica de oxigênio (DBO), excesso de CO2 (Excess-CO2), utilização aparente de oxigênio (AOU) para análise do metabolismo do rio, e &delta;13C e &delta;15N para o entendimento da origem do material orgânico particulado. Para isso, 19 estações de amostragem foram selecionadas ao longo dos canais do rio Camanducaia (8 estações) e Jaguari (11 estações), duas estações nos seus principais afluentes Mosquito e Camanducaia Mineiro, respectivamente, e outras duas estações em pequenos riachos nas áreas de cabeça do Jaguari e as bacias hidrográficas de Camanducaia. A exportação de elementos pela mesobacia do rio Jaguari foi avaliada pelos fluxos de carbono, nitrogênio e material particulado em suspensão fino e grosso. Não foi verificado características de anaerobiose nos rios Jaguari e Camanducaia, apesar de terem ocorrido eventos em que Excess-CO2 ultrapassou 250 &mu;M. Verificou-se a CE variando entre 15 e 156 &mu;S cm-1 no rio Jaguari, e de 27 a 175 &mu;S cm-1 no rio Camanducaia. Os pontos amostrais de áreas preservadas foram em média 5,8 e 3,7 vezes menores que os pontos a jusante no rio Jaguari e Camanducaia, respectivamente. A ACP reduziu as 9 variáveis relacionadas a variação espacial do carbono em 2 componentes, com alto nível de explicação (p<0,05), chamadas de qualidade de água (69,5%) e metabolismo do rio (16%). Os pontos a jusante dos rios foram altamente correlacionados entre si, e com as variáveis químicas (DOC, DIC e DBO) e número de habitantes. Para a dinâmica do nitrogênio relacionada ao uso da terra, covariáveis como CE, NOD, N-NH4+ TR e Q, apresentaram relação com os processos oxidativos e foram bons preditores para o nitrato. Ocorreu variação de N-NO3- de 3 a 139 &mu;M no rio Jaguari e entre 3 e 199 &mu;M no rio Camanducaia, obtendo correlação positiva com a CE (r=0,7), NOD (r=0,3) e inversa com o OD (r=-0,2). Assim, as diferentes zonas (cabeceira, trecho médio e jusante) da mesobacia do rio Jaguari influenciaram na distribuição de carbono e nitrogênio e essas estão associadas ao tipo de uso da terra, alterando a origem das fontes de N e C da matéria orgânica particulada. / The objective was to understand the effect of changes in land use on the distribution and transport of carbon and nitrogen in rivers of different orders in the Jaguari and Camanducaia river basins. The Jaguari River has the Camanduacia River as one of its main tributaries, and is an important supplier of the \"Cantareira\" reservoir system, which supplies about six million inhabitants of the Metropolitan Region of São Paulo, Brazil. In each medium-sized basin, a hydrological one-year study was initiated in January 2015 to monitor water quality parameters such as pH, electrical conductivity (CE), dissolved oxygen and percentage (OD), organic and inorganic carbon dissolved (DOC; DIC), total nitrogen (TN), air and water temperature (T °C), and flow rate (Q) were determined by the inorganic organic matter (DOC and DIC), nitrate (NO3-), ammonium (NH4+), nitrite (BOD), excess of CO2 (Excess-CO2), apparent oxygen used (AOU) for the analysis of river metabolism, &delta;13C and &delta;15N to understand the origin of the particulate organic material. For this purpose, 19 sampling stations were selected along the channels of the Camanducaia River (8 stations) and Jaguari (11 stations), two stations in their main tributaries Mosquito and Camanducaia Mineiro, respectively, and two stations in small streams in the headwater of the Jaguari and Camanducaia watersheds. The exportation of elements by the Jaguari river basin was evaluated by the fluxes of carbon, nitrogen and particulate matter in fine and coarse. No anaerobic characteristics were observed in the Jaguari and Camanducaia rivers, although events occurred in which Excess-CO2 exceeded 250 &mu;M. CE varied from 15 to 156 &mu;S cm-1 in the Jaguari River and from 27 to 175 &mu;S cm-1 in the Camanducaia River. The sample points of preserved areas were on average 5.8 and 3.7 times lower, than in the downstream points in the Jaguari and Camanducaia rivers, respectively. The ACP reduced the 9 variables related to the spatial variation of the carbon in 2 components, with a high level of explanation (p<0.05), called water quality (69.5%) and river metabolism (16%). The points downstream of the rivers were highly correlated with each other, and with the chemical variables (DOC, DIC and BOD) and number of inhabitants. For nitrogen dynamics related to land use, covariates such as EC, NOD, NH4+-N, TR and Q, were related to oxidative processes and were good predictors for nitrate. There was a variation of NO3- N between 3 and 139 &mu;M in the Jaguari River and 3 to 199 &mu;M in the Camanducaia River, obtaining a positive correlation with EC (r=0.7), NOD (r=0.3) and inverse OD (r=-0.2). Thus, the different zones (headwater, middle strecth and downstream) of the basin of the Jaguari River influenced the distribution of carbon and nitrogen and these are associated with the type of land use, changing the origin of N and C sources of particulate organic matter.
705

O ciclo do carbono na bacia do Alto Xingu: interações entre ambientes terrestre, aquático e atmosférico / The carbon cycle in the upper Xingu Basin: terrestrial, aquatic and atmospheric interactions.

Vania Neu 06 April 2009 (has links)
O objetivo da pesquisa foi quantificar os fluxos de entrada e saída de carbono (C) ao longo de um ano hidrológico, medidas estas importantes para o balanço de C num ecossistema. A microbacia em estudo apresenta uma área de 1319 hectares, o rio que drena esta microbacia é afluente do Rio Darro, Bacia do Rio Xingu, Mato Grosso Brasil. A cobertura vegetal é de Tensão Ecológica, área de contato entre a floresta tropical chuvosa e cerrado. Para estimar a entrada e o transporte de C no sistema, amostras de 12 eventos de chuva foram coletadas e determinadas as concentrações de carbono orgânico dissolvido (COD) e carbono inorgânico dissolvido (CID) na água da chuva, precipitação interna da floresta, escoamento de água pelo tronco, escoamento superficial do solo, solução do solo e água do lençol freático. Os fluxos de saída de C foram quantificadas em 13 eventos, com a determinação de CO2 e CH4 do rio e do solo, e a exportação de COD, CID e carbono orgânico particulado (COP) pelo rio. Na água da chuva as concentrações médias de COD foram de 6,7 ± 3,7 mg L-1, o que representou uma entrada de 82,3 Kg C ha-1 ano-1. Após o percurso através do dossel, a precipitação interna apresentou a maior quantidade de COD transportada no sistema, com valores de 142,6 Kg C ha-1 ano-1. O escoamento superficial do solo e o escoamento pelo tronco, contribuíram com apenas 1 a 2 % do COD transportado no sistema. No caso do CID, as concentrações nos compartimentos acima do solo foram muito baixas, semelhantes ao esperado pelo equilíbrio com o CO2 da atmosfera, ao passo que nos compartimentos abaixo do solo, houve supersaturação de CO2 e aumento considerável de CID. O solo foi a componente de maior perda de carbono do sistema, com fluxos para a atmosfera de mais de 6000 Kg C ha-1 ano-1, o que representou 99% da saída da microbacia. Para o CH4 o solo foi um pequeno sumidouro de carbono na ordem de 4,37 ± 0,09 Kg C ha-1 ano-1. O rio apresentou fluxos extremamente elevados de CO2 e CH4, com mais de 63000 Kg C ha-1 ano-1, porém as perdas pelo rio foram baixas quando comparadas com a área total da bacia (56,2 ± 0,07 Kg C ha-1 ano-1). Das frações exportadas na descarga pelo rio, o COD foi a fração dominante, porém relativamente baixa, com uma saída de 1,6 Kg C ha-1 ano-1. As perdas de CID e COP pelo rio foram de 0,9 Kg C ha-1 ano-1 e 0,01 Kg C ha-1 ano-1 respectivamente. Concentrações elevadas de COD nos compartimentos acima do solo, mostram uma clara variação sazonal, em parte, provavelmente como resultado das atividades humanas nesta região. As elevadas concentrações de CID na solução do solo e água do lençol freático durante o período chuvoso, associado aos maiores fluxos de CO2, indicam uma forte conectividade entre ambientes terrestre e aquático. / The objective of this research was to quantify the fluxes of carbon (C) input and output in a watershed during a hydrological year that represent important components for the C budget in an ecosystem. The watershed studied covered an area of 1319 ha, and is drained by the Darro River tributary, Xingu Basin, Mato Grosso state - Brazil. The area is characterized by a typical transition from evergreen tropical forest to Cerrado. In order to estimate the input and transport of C in the system, samples from 12 rain events were collected over the year and measured for dissolved organic carbon (DOC) and dissolved inorganic carbon (DIC) in the rainwater, throughfall, stemflow, overlandflow, soil solution, and groundwater. C fluxes were quantified in 13 sampling events for carbon dioxide (CO2) and methane (CH4) emissions from the stream and soil, and for DOC, DIC and particulate organic carbon (POC) exported by the stream. Mean annual DOC concentration in the rainwater was 6.7 ± 3.7 mg L-1 representing an input of 82.3 Kg C ha-1 yr-1. Throughfall represented the largest flow path of DOC in the system with an annual transport of 142.6 Kg C ha-1 yr-1. Stemflow and overlandflow contributed to 1 and 2% of the total DOC transported in the system. For dissolved inorganic carbon, the concentrations in aboveground compartments were very low, similar to what is expected as result of the equilibrium whith the atmosphere. In contrast, DIC concentration in the belowground flow paths was high due to supersaturation in relation to the CO2 concentrations in the atmosphere. Soil C emission was the largest carbon flow path in the basin, more than 6000 Kg C ha-1 yr-1, which represented 99% of C losses in the watershed. In the case of CH4 the soil acted as a C sink with a sequestration rate of 4.37 ± 0.09 Kg C ha-1 yr-1. The stream showed elevated fluxes of CO2 and CH4 of more than 63000 Kg C ha-1 yr-1 . However, compared to the entire basin area the losses from the stream were small (56.2 ± 0.07 Kg C ha-1 yr-1). Although the DOC concentration in the stream was low, it represented the main organic carbon loss component, with a flux of 1.6 Kg C ha-1 yr-1. Losses of DIC and POC from the stream amounted around 0.9 Kg C ha-1 yr-1 and 0.01 Kg C ha-1 yr-1, respectively. The high DOC concentrations in aboveground flow paths exibited clear seasonal variations, in part problably as a result of massive human activities in the region. Also, the high concentrations of DIC in the soil solution and in groundwater during the rainy season, associated with the highest CO2 fluxes, indicated the strong connectivity between terrestrial and aquatic environments.
706

Biogeoquímica do mercúrio na interface solo - atmosfera na Amazônia

Almeida, Marcelo Dominguez de 06 March 2018 (has links)
Submitted by Biblioteca de Pós-Graduação em Geoquímica BGQ (bgq@ndc.uff.br) on 2018-03-06T14:46:37Z No. of bitstreams: 1 Marcelo Dominguez de Almeida.pdf: 2592100 bytes, checksum: a3a8a6cb2778e20f23f3d76689b2ed97 (MD5) / Made available in DSpace on 2018-03-06T14:46:37Z (GMT). No. of bitstreams: 1 Marcelo Dominguez de Almeida.pdf: 2592100 bytes, checksum: a3a8a6cb2778e20f23f3d76689b2ed97 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico / Universidade Federal Fluminense. Instituto de Química. Programa de Pós-Graduação em Geoquímica, Niterói, RJ / O uso de mercúrio nos garimpo na Amazônia sofreu uma diminuição considerável quando comparado com as emissões das décadas de 80 e 90. Contudo, os níveis de mercúrio em peixes, e por consequencia, na população ribeirinha permanece altos. Os objetivos desse trabalho forma quantificar os estoques de mercúrio contido solos da Bacia do Rio Madeira; medir as emissões de mercúrio gasoso do solo atmosfera; e avaliar a influência do uso do solo tanto nos estoque quanto na emissão de mercúrio. / The use of mercury in mining in the Amazon has suffered a considerable decrease when compared to the emissions of the 1980s and 1990s. However, mercury levels in fish and consequently in the riverine population remain high. The objectives of this work are to quantify the stocks of mercury contained in the Madeira River basin; measure emissions of mercury gaseous soil atmosphere; and to evaluate the influence of the use of the soil in both the inventory and the emission of mercury.
707

Emissões de CO2 como parâmetro da avaliação do ciclo de vida do amido de milho plastificado com glicerol destinado à compostagem / CO2 emissions as a life cycle assessment parameter of plasticized starch for composting conditions

Allganer, Katlen 10 May 2010 (has links)
Orientador: Lúcia Helena Innocentini Mei / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-17T00:20:01Z (GMT). No. of bitstreams: 1 Allganer_Katlen_M.pdf: 1913407 bytes, checksum: 0db427a1d4ddf8feb850924e6810f020 (MD5) Previous issue date: 2010 / Resumo: As sociedades hoje têm de enfrentar os problemas resultantes dos padrões de consumo, como a geração de resíduos e sua destinação em áreas inadequadas, com conseqüentes impactos ambientais que dependem da composição dos resíduos e do tipo de disposição. Gerenciar a geração de resíduos significa administrar o processo produtivo e o consumo de bens, viabilizando o retorno dos materiais ao meio ambiente sem causar danos. Assim, é importante avaliar todo o ciclo de um processo, para promover a melhoria do desempenho ambiental de um produto e o uso de tecnologias sustentáveis. Diante desta realidade, o objetivo deste estudo foi avaliar as emissões de gases de efeito estufa durante etapas específicas do ciclo de vida do amido de milho plastificado com glicerol (plantio de milho e compostagem), fundamentando conhecimentos sobre os conceitos da Avaliação de Ciclo de Vida; e contribuindo com possíveis novos direcionamentos no uso de embalagens plásticas destinadas à compostagem, com conseqüente redução no uso de recursos não renováveis. Deste modo, este trabalho visa marcar o início de uma linha investigatória ainda incipiente na Unicamp, por tratar-se de um assunto pouco estudado e com muitas restrições na coleta de dados; e alertar a comunidade nacional sobre a importância deste tipo de estudo para o desenvolvimento sustentável tão apregoado no mundo todo. Os valores de emissões de CO2 obtidos neste estudo assemelham-se aos resultados divulgados na literatura internacional, considerando as restrições e a abrangência estabelecidas no escopo dos estudos comparados. Utiliza-se a metodologia de gestão ambiental, a Avaliação do Ciclo de Vida, descrito pelas Normas NBR 14040 e 14044, para orientações de divulgação dos resultados obtidos. A base de dados utilizada literatura e parte experimental, em que a amostra de amido de milho plastificado com glicerol é produzida em misturador de alto cisalhamento e submetida ao teste de biodegradação sob a Norma ASTM D5988-03 / Abstract: Today society has to face problems that result from consumerism, like waste production and its inadequate disposal, with consequent environmental impacts that are linked to waste composition and kind of disposal. Managing waste production means to control the productive processes and the consuming of goods, in a way that waste materials return to the environment without causing much impact. It is then important to evaluate all the full cycle of a process in order to enhance the environmental performance of a product and the use of sustainable technologies. Under these concepts, the objective of this study was to assess greenhouse gases emissions during specific stages of the plasticized corn starch life cycle (corn growing and composting), underlying the knowledge of Life Cycle Assessment concepts; and contributing with possible new directions to the use of plastic packages for composting, with consequent reduction of non-renewable sources. Furthermore, this work aims to start an investigative line still incipient at Unicamp, for not being a very well known subject and with a lot of restrictions in data collection; and warn the national community about this kind of study for the sustainable development so publicized in the world. The results of CO2 emissions obtained in this study are similar to the results found in international works, considering the restrictions and the established range in the scope of the compared studies. It is used the environmental management tool, Life Cycle Assessment, described by Brazilian standards NBR 14040 and 14044 as orientation for results publication. As database, it is made a literature review and an experimental part, in which a corn starch sample is plasticized with glycerol in a high shear mixer and gone under biodegradation test using ASTM D5988-03 standard / Mestrado / Ciencia e Tecnologia de Materiais / Mestre em Engenharia Química
708

BiogeoquÃmica de Ferro e Enxofre em Solos de um Manguezal no Contexto SemiÃrido Cearense (AcaraÃ) / Biogeochemistry of Iron and Sulphur in Mangrove Soils in the Semiarid Cearense Context (AcaraÃ)

Camila Campos Lopes Moreira 28 February 2011 (has links)
CoordenaÃÃo de AperfeiÃoamento de NÃvel Superior / Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / Os manguezais sÃo ecossistemas complexos e que possuem uma dinÃmica marcada pela interaÃÃo de diversos fatores, tanto biÃticos (vegetaÃÃo, macrobiota), quanto abiÃticos (temperatura, regime de chuvas, amplitude das marÃs). A interaÃÃo desses fatores influencia diretamente as condiÃÃes fÃsico-quÃmicas e biolÃgicas do meio, refletidas em parÃmetros como pH e Eh. Nas Ãreas de manguezais, condiÃÃes como o hidromorfismo fazem com que a forma preponderante de obtenÃÃo de energia seja a ReduÃÃo Bacteriana do Sulfato, que està diretamente relacionada com o ciclo do ferro desses locais. Diante disso, percebe-se a necessidade de mais estudos nesse ramo da CiÃncia do Solo, tendo em vista que os processos envolvidos nesses locais ainda sÃo pouco conhecidos, principalmente nos manguezais de Ãreas de clima semiÃrido. Sendo a regiÃo do estuÃrio do rio Acaraà â CE uma Ãrea inserida nesse contexto e com sazonalidade marcante, um estudo do solo e da Ãgua intersticial dessa Ãrea foi realizado com o objetivo de se avaliar o comportamento das espÃcies de ferro e enxofre, levando-se em consideraÃÃo parÃmetros tais como as variaÃÃes estacionais da regiÃo, profundidade e presenÃa ou nÃo da vegetaÃÃo, bem como a atividade microbiana. Para obtenÃÃo de um estudo detalhado desses solos, foram determinados pH, Eh, teor de matÃria orgÃnica, sulfato e cloreto na Ãgua intersticial, salinidade, extraÃÃo sequencial de ferro, bem como a respirometria em trÃs Ãreas do manguezal do rio Acaraà com predomÃnio de plantas do gÃnero Rhizophora e Avicennia, bem como em uma Ãrea nÃo vegetada. De uma forma geral, os dados obtidos mostram que os manguezais sÃo Ãreas levemente Ãcidas ou atà mesmo alcalinas, alÃm de serem ambientes fortemente redutores. Dentre as fraÃÃes de ferro analisadas, observa-se que suas concentraÃÃes variam entre as Ãreas, uma vez que as condiÃÃes fÃsico-quÃmicas predominantes nos pontos de amostragem escolhidos sÃo diferentes entre si. AlÃm disso, observou-se que a transiÃÃo do perÃodo chuvoso para o de estiagem promove um maior acÃmulo de sais no solo, evidenciado pelos aumentos das concentraÃÃes dos Ãons e dos valores de salinidade. Nesse contexto, o aumento da taxa de evapotranspiraÃÃo surge como fator determinante para mudanÃas nas condiÃÃes fÃsico-quÃmicas do meio, pois promove uma circulaÃÃo de ar no solo mais eficiente. Por fim, foi constatado que os parÃmetros analisados e a presenÃa da vegetaÃÃo local possuem uma relaÃÃo de interdependÃncia bastante significativa e desempenham um papel fundamental na dinÃmica do ecossistema. AlÃm disso, observou-se que a sazonalidade marcante da regiÃo e os fatores por ela governados contribuem de forma direta para a oxidaÃÃo de sulfetos, alterando a mineralogia e as caracterÃsticas fÃsico-quÃmicas das Ãguas intersticiais e solo desse manguezal. / Mangroves ecosystems are complex and have a dynamic marked by the interaction of several factors, both biotic (vegetation, macrobiotics), and abiotic (temperature, rainfall, tidal range). The interaction of these factors influences directly the physicalchemical and biological environment, reflected in parameters such as pH and Eh. In mangrove areas, as conditions hydromorphism cause the prevailing form of procurement of energy is the bacterial sulfate reduction, which is directly related to the iron cycle of these locations. Given this, we see the need for further studies in this branch of Soil Science, in view of the processes involved in these places are still poorly understood, especially in mangrove areas in semiarid climate. Since the estuary of the river Acaraà â CE an area within this context and with marked seasonality, a study of soil and pore water of this area was conducted with the aim of evaluating the behavior of iron and sulfur species, taking into account parameters such as seasonal variation in the region, depth and presence or absence of vegetation, and microbial activity. To obtain a detailed study of soils, soil pH, Eh, organic matter content, sulfate and chloride in pore water, salinity, sequential extraction of iron and respirometry were done in three areas of mangrove river Acaraà predominantly plant the genus Rhizophora and Avicennia, as well as a non-vegetated area. Overall, our data show that mangrove areas are slightly acidic or even alkaline environments and are strongly reducing. Among the fractions analyzed for iron, it is observed that their concentrations vary between areas, since the physicochemical conditions prevailing at the sampling points chosen are different. Furthermore, we observed that the transition from rainy to dry season promotes a greater accumulation of salts in the soil, as evidenced by increases in ion concentrations and salinity. In this context, the increased rate of evapotranspiration emerges as a determinant for changes in the physicochemical conditions of the medium, because it causes a movement of air in the soil more efficiently. Finally, we found that the parameters measured and the presence of local vegetation have an interdependent relationship and play a very significant role in ecosystem dynamics. Furthermore, we observed that the marked seasonality of the region and the factors which it ruled directly contribute to the oxidation of sulfides by changing the mineralogy and the physico-chemical properties of soil and interstitial waters of mangrove.
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A Comparative Analysis of Portable X-ray Fluorescence Spectrometry and Stable Isotopes in Assessing Ancient Coastal Peruvian Diets

Gilbertson, Theresa Jane 19 November 2015 (has links)
This dissertation explores a cross-cultural analysis of the dietary signatures of four coastal cultures of prehistoric Peru. A combination of elemental analysis based on portable x-ray fluorescence spectrometry (pXRF), testing trace elements presented in 209 individuals’ skulls representing the Nazca (38), Cañete (33), Lima (40), and Moche (98) valleys and/or cultures of the first millennium AD, is weighed in conjunction with isotope ratio mass spectrometry (IRMS) to analyze human bone collagen and bone apatite derived from a portion of the individuals represented in the Nazca, Cañete, and Lima cranial samples. Evidence from the results of both tests are weighed using descriptive statistics supported with bivariate correlations and linear regression to determine that the pXRF data on the trace elements strontium (Sr), barium (Ba), and iron (Fe) from the Moche collection do present potential for accurately portraying diet of those individuals represented in this sample. Additional hypotheses tested include potential for preferential diets based on sex, age, and status as well as attempting to place the valley of Cañete in the cultural sphere of either Lima or Nasca during the Early Intermediate Period. While there was no significant statistical difference in diet based on age in any of the individual valley datasets, there was one valley, Nazca, which showed a considerable variation in diet based on sex. From data derived from this particular sample set, there are mixed results in attempting to apply status to a diet of preferential high nitrogen sources such as marine mammals and large fish. In attempting to place Cañete in the cultural sphere of either Lima or Nasca, it was determined that cultural remains appear to be linked predominately to artifacts and practices of the Lima Culture, but the dietary difference in both stable isotope and trace elements signatures combined with the samples which instead aligned more closely with the Nasca Culture suggests that perhaps Cañete was a marginal space which allowed for the settlement and interaction of peoples from both neighboring cultures without prejudice. Overall, results indicate it would be premature to suggest pXRF replace destructive analysis in determination of diet. Due to the small sample size of stable isotopes deemed viable in testing, it is suggested that a larger sample of stable isotopes should be considered in similar testing and that the major elements from pXRF should also be used before a suggestion that destructive analysis was no longer warranted in many cases for deducing diet in ancient populations.
710

A study of the dissolution of atmospherically derived trace metals into North Atlantic seawater

Fishwick, Matthew Paul January 2016 (has links)
The aim of this study was to investigate the factors that affect the dissolution of a suite of trace metals from aerosols into seawater from wet and dry deposition, with a focus on important trace metals: manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu) and lead (Pb). To this end, aerosol and rainwater samples were collected from Tudor Hill (Bermuda) and Penlee Point (Cornwall) atmospheric observatories and surface seawater samples were collected from the Sargasso Sea and the Celtic Sea. These representative aerosol, rainwater and seawater samples were used in aerosol leaching and rainwater mixing experiments, which simulated the processes of mixing and trace metal dissolution following wet and dry deposition as closely as possible within the laboratory. Key variables were changed to investigate the effect of aerosol source/composition, seawater temperature, pH, dissolved oxygen concentration and organic ligand amendments on aerosol and rainwater trace metal dissolution. Results for aerosol leaching experiments revealed that changes to key physico-chemical conditions had little effect on the amount of Mn, Fe, Co, Ni and Pb leached from aerosols and therefore plausible future changes in ocean surface temperature, pH and oxygenation are unlikely to affect the flux of these important trace metals to surface waters. Conversely, aerosol source and composition had a significant effect on the dissolution of aerosol Fe, Co and Pb, with the most anthropogenically influenced aerosol samples displaying the highest solubilities. Therefore, future changes in land use and fossil fuel combustion are likely to affect the flux of these metals to the surface ocean. Fractional solubilities were in the range of 50 – 104% for Mn, 0.3 – 3.2% for Fe, 29 – 58% for Co, 40 – 85% for Ni and 67 – 112% for Pb. In addition, novel empirical relationships were found between the fractional solubilities of Fe, Co and Pb and enrichment factors for antimony, vanadium, Ni and Cu. This suggests that these fractional solubilities in seawater could be predicted using only total aerosol trace metal concentrations. The use of ultrafiltration provided unique insight into the size fractionation (colloidal 0.02 – 0.4 μm; soluble < 0.02 μm) of dissolved aerosol trace metals and showed Fe and Pb were mostly colloidal (77 – 98% colloidal), Mn and Co were mostly soluble (0 – 48% colloidal) and Ni showed a mixed profile (6 – 58% colloidal) when released from aerosols into ambient seawater. However, in the presence of a sufficient concentration of strong organic ligands the majority colloidal Fe was converted to soluble Fe (up to 100% soluble). Some of these organic ligands were also able to increase the soluble fraction of dissolved aerosol Mn. Similarly, the presence of organic ligands in rainwater maintained Mn, Fe, Co, Cu and Pb in the dissolved phase following delivery by rain into seawater. Rainwater ligands had no effect on the typically varied size fractionation profile of Mn, Fe, Co and Cu in rainwater mixed with seawater, UV-irradiation of rainwater, however, shifted the size fractionation of Pb in rainwater/seawater mixtures from 80 – 100% colloidal to 13 – 63% soluble, indicating that Pb-binding rainwater ligands are either colloidal or attached to colloidal matter. These findings highlight the importance of organic ligands in rainwater and seawater for retaining trace metal micronutrients and toxicants in the surface ocean, with implications for primary production.

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