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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.
41

Underlying patterns that shape ecological restoration in the post-colonial landscape of the Ainu Moshir (land) of Hokkaido, Japan

Shiga, Shinsaku 31 August 2011 (has links)
My main objective is to reveal and illustrate the patterns and processes underlying the practice of ecological restoration in post-colonial landscapes. To focus my analysis, I asked what these patterns are, and how they inhibit or enable the Iwor (Ainu Traditional Living Space) Restoration Project (IRP). The IRP is a state-funded project aimed at improving the well-being of Ainu in Hokkaido, Japan. I used interviews, participant observation and text analyses to elucidate the dynamics at work in and around the project. My findings suggest that colonial and technological practices inhibit good ecological restoration practices in IRP by disengaging people, or more subtly preventing them from engaging with it. Colonially, structural and discursive marginalization maintains economic deprivation through denying progressive conversations about community empowerment. This process also reinforces subjective power relationships of Wajin, the ethnic majority, dominance. Technologically, I observed signs of Borgmann’s (1984) “device paradigm” that are both institutionally (e.g. government agencies) and materially (e.g. infrastructure and tools) driving the IRP toward technological restoration and away from focal restoration. This was particularly apparent in such instances where means and ends were inverted, or the government agencies were inaccessible to the Ainu participants. These patterns in turn make IRP less appealing for Ainu and other local peoples. However, I also found that the room for creativity and attention to human-nature relationships in ecological restoration allow creation of the new space where Ainu can assert their values more strongly. This is the Kotan Iwor where the space embodies both Iwor and iwor, two representations of Wajin and Ainu views of the “Traditional Living Space” respectively. My findings on Kotan Iwor (the traditional settlement restoration site) suggest that there is a significant potential in the ecological restoration practices because of the practice’s inherent capacity to bring people and the landscape together in a creative context. With careful attention to colonial, technological, and other dynamics, good ecological restoration practices have the potential to restore and improve the well-being of indigenous and non-indigenous community members alike. / Graduate
42

Characterizing the Mixed-Severity Fire Regime of the Kootenay Valley, Kootenay National Park

Kubian, Richard 24 September 2013 (has links)
Understanding historic fire regimes to develop benchmarks for emulating historic natural disturbance processes in the interest of conserving biodiversity has been actively pursued for approximately 30 years. Mixed-severity fire regimes are increasingly becoming a recognized component of historic fire regimes. Mixed-severity fire regimes are inherently difficult to classify and characterize given the complexity of the process and the multiple scales at which this complexity is expressed. I utilized a systematic study design to gather fire scar and stand dynamic information in order to describe and classify the historic fire regime. I established the presence of mixed disturbance regime dominated by a mixed-severity fire regime. The historic fire regime was mixed-severity over time dominated by individual high severity fire events occurring at a frequency of 60-130 years with some areas that experienced lower severity fire events occurring at a frequency of 20 - 40 years. Twenty-one per cent of the current landscape was dominated by high-severity fire, 42% by mixed-severity and 37% had an unknown fire history. I developed a fire regime classification scheme that provides a useful tool for considering fire severity in mixed-severity system with forest species that generate strong establishment cohorts. I was able to combine time-since-fire methods with a systematic study design and this combination provided an excellent tool to explore mixed-severity fire characteristics in a complicated mixed-disturbance forest. I found limited relationships between topographic controls and fire severity. I found a number of significant relationships that fit the broadly held perceptions of how fire severity would affect species relative densities and stand structure attributes. The existing stand origin map and the Vegetation Resource Inventory stand age were largely accurate for high-severity 20th century fires but had decreasing accuracy in older forests and for mixed and unknown fire severity. The accuracy of the Vegetation Resource Inventory leading species accuracy was quantified at only 60%. My results have implications for fire and forest management in south-eastern British Columbia and in other forest systems that had historic mixed-severity fire regimes with tree species that have strong establishment cohorts. / Graduate / 0478 / 0329 / rick.kubian@pc.gc.ca
43

Recreating a functioning forest soil in reclaimed oil sands in northern Alberta

Rowland, Sara Michelle 05 1900 (has links)
During oil-sands mining all vegetation cover, soil, overburden and oil-sand is removed, leaving pits several kilometres wide and hundreds of metres deep. These pits are reclaimed by a variety of treatments using mineral soil or a mixed peat and mineral soil as the capping layer and planted with trees with natural colonisation from adjacent sites. A number of reclamation treatments covering different age classes were compared with a range of natural forest ecotypes to identify the age at which the treatments become similar to a natural site with respect to vegetation composition and key soil attributes relevant to nutrient cycling. Ecosystem function was estimated from plant community composition, litter decomposition, development of an organic layer and bio-available nutrients. Key response variables including moisture, pH, C:N ratios, bio-available nutrients and ground-cover were analysed by non-metric multidimensional scaling and cluster analysis to discover which reclamation treatments were moving towards or merging with natural forest ecotypes and at what age this occurs. On reclaimed sites, bio-available nutrients including nitrate generally were above the natural range of variability but ammonium, phosphorus, potassium, sodium and manganese were generally very low and limiting to ecosystem development. Plant diversity was similar to natural sites from 5 years to 30 years after reclamation, but declined as reclaimed sites approached canopy closure. Grass and forb leaf litters decomposed faster than aspen or pine in the first year, but decomposition on one reclamation treatment fell below the natural range of variability. Development of an organic layer appeared to be facilitated by the presence of shrubs, while forbs correlated negatively with first-year decomposition of aspen litter. The better restoration amendments for tailings sands involved repeated fertilisation of peat: mineral mixtures in the early years of plant establishment, these became similar to a target ecotype at about 25 years. Good results were also shown by subsoil laid over non-saline overburden and fertilised once, these became similar to a target ecotype at about 15 years. Other treatments receiving a single application of fertiliser remain entrenched in the early reclamation phase for up to 25 years.
44

The path to selfless restoration: interconnectedness between Bhikkhu Buddhadasa and ecological restoration

Ralph, Jeff 16 January 2009 (has links)
Ecological restoration projects provide the opportunity for individuals to reconnect with the natural environment. However, the actions and approaches of some ecological restorationists should be brought into question. The concern is that while restoration projects often feature a great deal of public input, hard engineering and site manipulation, they are still based on human-centered priorities. Several scholars in the emerging field of Buddhism and Ecology have applied Buddhist teachings to studies in ecology to advocate a selfless, interconnected approach between humans and ecosystems. However, there has been no work devoted to interconnectedness between Buddhism and the practice and promise of ecological restoration. In this thesis we follow the path of the Buddha, Bhikkhu Buddhadasa and the practitioners and philosophers of ecological restoration to discover if Buddhadasas’ teachings and interpretations of paţicca-samuppāda (dependent origination) and anattā (no-self) will be able to help restorationists approach ecological restoration in a more interconnected and selfless way.
45

O estado da arte da ecologia da restauração e sua relação com a restauração de ecossistemas florestais no bioma Mata Atlântica

Oliveira, Renata Evangelista de [UNESP] 27 May 2011 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:35:46Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-05-27Bitstream added on 2014-06-13T19:46:47Z : No. of bitstreams: 1 oliveira_re_dr_botfca.pdf: 1831819 bytes, checksum: a75182471af185c74b3c1efcc3b6973f (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / O presente trabalho teve como objetivos (i) Levantar e analisar as pesquisas desenvolvidas em ecologia da restauração, com foco nos pressupostos para o desenvolvimento da restauração ecológica; (ii) Analisar o estado da arte da restauração florestal no Brasil, tendo como foco principal as publicações e ações de restauração de ecossistemas florestais no Bioma Mata Atlântica. Para isso, foi realizada (i) uma investigação teórico-conceitual, análise documental e cronológica com foco na restauração ecológica e na restauração florestal no Brasil, (ii) uma análise comparativa entre o arcabouço bibliográfico existente para a Ecologia da Restauração, em diferentes regiões no mundo e as publicações e ações realizadas no Brasil; (iii) uma análise da evolução histórica da pesquisa em restauração florestal no Brasil, com foco no Bioma Mata Atlântica; (iv) o desenvolvimento de uma metodologia para análise situacional de estudos de caso (projetos e ações em restauração florestal); (v) o levantamento de indicadores de monitoramento e avaliação, para discussão sobre os atributos de ecossistemas restaurados e de características de uma boa restauração ecológica. No Capítulo I foram analisados 617 artigos e 76 textos editoriais, publicados em 14 periódicos de 1980 a 2008. Desses artigos, 26 referiram-se a pesquisas em ecossistemas florestais tropicais. Foi observado aumento crescente de artigos com o tempo, e a maioria das pesquisas se referiu a ecossistemas temperados. Uma análise dos filtros ecológicos enfocados demonstrou que, para ecossistemas tropicais, as ações de restauração estão relacionadas à regeneração natural, interações ecológicas e à manutenção de um pool de espécies mínimo para as comunidades estudadas. O Capítulo II traz uma caracterização e análise cronológica das ações de restauração na Mata Atlântica... / This study aimed to (i) Analyze the research conducted in Restoration Ecology, focusing on the assumptions for the development of ecological restoration, (ii) analyze the state of art of forest restoration in Brazil, focusing mainly on publications and actions to restore forest ecosystems in the Brazilian Atlantic Forest. For this, we performed (i) a theoretical-conceptual research, documental and chronological analysis focusing on ecological restoration and forest restoration in Brazil, (ii) a comparative analysis between the existing framework for the literature of Restoration Ecology, in different regions in the world and the publications and actions taken in Brazil; (iii) an analysis of the historical evolution of research on forest restoration in Brazil, focusing on the Atlantic Forest Biome; (iv) the development of a methodology for situational analysis of study cases (projects and activities in forest restoration), (v) the provision of monitoring and evaluation indicators for discussion about the attributes of restored ecosystems and characteristics of a good ecological restoration. In Chapter I we analyzed 617 articles and 76 editorial texts, published in 14 journals from 1980 to 2008. Of these articles, 26 referred to research in tropical forest ecosystems. We observed an increasing number of articles in time, and most researches have referred to temperate ecosystems. An analysis of ecological filters focused shown that for tropical ecosystems, the restoration actions are related to natural regeneration, ecological interactions... (Complete abstract click electronic access below)
46

Padrões fenológicos em ecossistemas em processo de restauração e em fragmento florestal vizinho /

Homem, Marcos das Neves Gusmão, 1982- January 2011 (has links)
Orientador: Vera Lex Engel / Banca: Fátima Conceição M. Pina-Rodrigues / Banca: Giselda Durigan / Resumo: A avaliação do sucesso da restauração depende do monitoramento de indicadores de trajetórias sucessionais em áreas restauradas, em relação a ecossistemas de referência. A fenologia também pode ser utilizada como um critério de monitoramento nestas áreas, por estar associada aos processos de reprodução, recrutamento e herbivoria nessas comunidades. Estudos fenológicos de espécies plantadas são essenciais para que se conheça seu comportamento em um ambiente diferente do natural. O objetivo deste trabalho foi analisar se comunidades em processo de reestruturação apresentam funcionamento semelhante a um ecossistema de referência, em relação a alguns aspectos fenológicos. O estudo foi realizado no município de Botucatu, SP, onde foi instalado há 11 anos um experimento de diferentes modelos de restauração com 5 tratamentos e três repetições. O fragmento de referência tem cerca de 303 ha, e situa-se a 100 m do experimento de restauração. Foram observadas quinzenalmente e quantificadas as fenofases: floração, frutificação, brotamento e mudança foliar. Foram selecionados 333 indivíduos no fragmento florestal de 48 espécies. Na área restaurada foram selecionados indivíduos de todas as espécies encontradas em idade reprodutiva e algumas que ainda não a atingiram, somando 363 indivíduos de 46 espécies. Foram computadas as intensidades médias das fenofases por quinzena entre todas as espécies estudadas. Para indicar a porcentagem de indivíduos que estavam manifestando determinada fenofase foi calculado o índice de atividade. Foi calculado também o índice de sazonalidade para cada fenofase em cada tratamento. A atividade da fenofase floração e frutificação foram maiores nos indivíduos da área em restauração o que pode estar relacionada à menor competitividade e maior disponibilidade de radiação solar... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The evaluation of the success of restoration depends on the monitoring indicators of successional trajectories in restored areas, in relation to reference ecosystems. Phenology can also be used as a criterion for monitoring these areas because it is associated to the processes of reproduction, recruitment and herbivory in these communities. Phenological studies of planted species are essential to know whether their behavior in an environment different from natural. The objective was to examine whether communities in the restructuring process have run similar to an ecosystem of reference in relation to some aspects of phenology. The study was conducted in Botucatu, Brazil, where it was installed 11 years ago an experiment with different models catering with 5 treatments and three replications. The fragment in question has about 303 ha and is located 100 m from the restoration experiment. Were observed and quantified fortnightly phenophases flowering, fruiting, budding and leaf changes. We selected 333 individuals in 48 species of forest fragment. In the restored area were selected individuals of all species found in reproductive age and some who have not yet reached, totaling 363 individuals from 46 species. We computed the mean intensities of both clones by half of all species. To indicate the percentage of individuals who were expressing particular phenology index was calculated activity. The index was also calculated for each seasonal phenology in each treatment. The activity of flowering and fruiting phenology were higher in subjects from the area in which restoration may be related to lower competitiveness and greater availability of solar radiation. The melittophily and zoochory syndromes were more frequent, being found in 4 of 5 treatments in restoration of the area and this is the pattern found in the forest fragment. All treatments were most brevideciduous species... (Complete abstract click electronic access below) / Mestre
47

O estado da arte da ecologia da restauração e sua relação com a restauração de ecossistemas florestais no bioma Mata Atlântica /

Oliveira, Renata Evangelista de, 1971- January 2011 (has links)
Orientador: Vera Lex Engel / Banca: Giselda Durigan / Banca: Luiz Mauro Barbosa / Banca: Luiz Fernando Duarte de Moraes / Banca: Ricardo Ribeiro Rodrigues / Resumo: O presente trabalho teve como objetivos (i) Levantar e analisar as pesquisas desenvolvidas em ecologia da restauração, com foco nos pressupostos para o desenvolvimento da restauração ecológica; (ii) Analisar o estado da arte da restauração florestal no Brasil, tendo como foco principal as publicações e ações de restauração de ecossistemas florestais no Bioma Mata Atlântica. Para isso, foi realizada (i) uma investigação teórico-conceitual, análise documental e cronológica com foco na restauração ecológica e na restauração florestal no Brasil, (ii) uma análise comparativa entre o arcabouço bibliográfico existente para a Ecologia da Restauração, em diferentes regiões no mundo e as publicações e ações realizadas no Brasil; (iii) uma análise da evolução histórica da pesquisa em restauração florestal no Brasil, com foco no Bioma Mata Atlântica; (iv) o desenvolvimento de uma metodologia para análise situacional de estudos de caso (projetos e ações em restauração florestal); (v) o levantamento de indicadores de monitoramento e avaliação, para discussão sobre os atributos de ecossistemas restaurados e de características de uma boa restauração ecológica. No Capítulo I foram analisados 617 artigos e 76 textos editoriais, publicados em 14 periódicos de 1980 a 2008. Desses artigos, 26 referiram-se a pesquisas em ecossistemas florestais tropicais. Foi observado aumento crescente de artigos com o tempo, e a maioria das pesquisas se referiu a ecossistemas temperados. Uma análise dos filtros ecológicos enfocados demonstrou que, para ecossistemas tropicais, as ações de restauração estão relacionadas à regeneração natural, interações ecológicas e à manutenção de um pool de espécies mínimo para as comunidades estudadas. O Capítulo II traz uma caracterização e análise cronológica das ações de restauração na Mata Atlântica... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: This study aimed to (i) Analyze the research conducted in Restoration Ecology, focusing on the assumptions for the development of ecological restoration, (ii) analyze the state of art of forest restoration in Brazil, focusing mainly on publications and actions to restore forest ecosystems in the Brazilian Atlantic Forest. For this, we performed (i) a theoretical-conceptual research, documental and chronological analysis focusing on ecological restoration and forest restoration in Brazil, (ii) a comparative analysis between the existing framework for the literature of Restoration Ecology, in different regions in the world and the publications and actions taken in Brazil; (iii) an analysis of the historical evolution of research on forest restoration in Brazil, focusing on the Atlantic Forest Biome; (iv) the development of a methodology for situational analysis of study cases (projects and activities in forest restoration), (v) the provision of monitoring and evaluation indicators for discussion about the attributes of restored ecosystems and characteristics of a good ecological restoration. In Chapter I we analyzed 617 articles and 76 editorial texts, published in 14 journals from 1980 to 2008. Of these articles, 26 referred to research in tropical forest ecosystems. We observed an increasing number of articles in time, and most researches have referred to temperate ecosystems. An analysis of ecological filters focused shown that for tropical ecosystems, the restoration actions are related to natural regeneration, ecological interactions... (Complete abstract click electronic access below) / Doutor
48

Regeneração natural de um fragmento de cerrado degradado com a formação de pastagens de braquiária (Urochloa decumbens (Stapf) R. D. Webster) /

Rissi, Mariana Ninno. January 2011 (has links)
Orientador: Omar Cavassan / Banca: Marco Antonio Batalha / Banca: Veridiana de Lara Weiser / Banca: Giselda Durigan / Banca: Ingrid Koch / Resumo:Os conceitos de ambiente degradado e ambiente perturbado foram inicialmente propostos com base na observação de tais processos em fragmentos de matas. Ambientes perturbados quando sujeitos a agentes, conseguem se restabelecer após a retirada do causador da perturbação. Porém, quando a ação ocorre de forma mais intensa, de modo a eliminar todo o potencial de retorno às condições semelhantes às anteriores, a vegetação é considerada degradada. Questiona-se se as mesmas ações que tornariam uma floresta degradada teriam a mesma consequência em fragmentos de cerrado. O presente estudo tem como finalidade analisar a composição da comunidade regenerativa, ao longo de um ano, em um fragmento de cerrado localizado no Jardim Botânico Municipal de Bauru-SP (JBMB). Busca-se ainda fornecer subsídios à compreensão dos processos ecológicos envolvidos na regeneração natural de áreas de cerrado degradadas e no combate químico como alternativa viável ou não para o controle de plantas invasoras. Além de contribuir para o conhecimento da flora do cerrado da região de Bauru. Para isso, algumas questões foram levantadas. Como ocorre a regeneração natural da vegetação lenhosa de um cerrado degradado? O combate químico às invasoras provocaria mudanças no desenvolvimento de plantas de cerrado? A intervenção no controle de plantas invasoras é desejável? A área de estudo foi desmatada por ação de posseiros, que se instalaram no local em 1997. Em 2007 houve a averbação da área ao Jardim Botânico Municipal de Bauru. Durante este período a área de vegetação nativa foi retirada para a formação de pastagens. Por dois anos o local ficou abandonado, sendo possível observar a regeneração natural da vegetação. Para avaliar o potencial de regeneração natural do cerrado, foi efetuado um levantamento florístico e fitossociológico comparativo... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The concepts degraded environment and disturbed environment were initially proposed based on the observation of such processes in forest fragments. Disturbed environments, when subjected to agents, can reestablish after the removal of the disturbing factor. However, when the action is more intense and there is no potential to return to conditions similar to the previous ones, the vegetation is considered degraded. The question is: Would the actions that make a forest degraded have the same consequence in cerrado fragments? The present study aims to analyze the composition of the regenerative community over one year in a cerrado fragment located in the Municipal Botanical Garden of Bauru City, São Paulo State, Brazil (JBMB); to provide data to understand the ecological processes involved in the natural regeneration of degraded cerrado areas and the chemical combat as a viable alternative or not to control alien plants; and to contribute to the knowledge of the cerrado flora in Bauru region. Thus, some questions were raised. How does natural regeneration of the woody vegetation of a degraded cerrado occur? Would the chemical combat against invasive alien plants change the development of cerrado plants? Is intervention in the control of those plants favorable? The study area was deforested by the action of settlers, who established there in 1997. In 2007 the area was endorsed to the Municipal Botanical Garden of Bauru City (JBMB). During this period, the native vegetation was substituted for pasture. By two years ago the place has been abandoned and the natural vegetation started to regenerate. To evaluate the natural regeneration potential of cerrado, a comparative floristic and phytosociological survey was carried out in three areas inside JBMB. The first area is inserted in a "cerradão" fragment, free of... (Complete abstract click electronic access below) / Mestre
49

Trace metals biogeochemistry in soils and plants affected by mining waste rocks: consequences to ecosystem and options for restoration (Phytoremediation abd technosols) / Trace metals biogeochemistry in soils and plants affected by mining waste rocks: consequences to ecosystem and options for restoration (Phytoremediation abd technosols)

Perlatti, Fabio January 2015 (has links)
PERLATTI, Fábio. Trace metals biogeochemistry in soils and plants affected by mining waste rocks: consequences to ecosystem and options for restoration (Phytoremediation abd technosols). 2015.165 f. Tese (Doutorado em Ecologia e Recursos Naturais)-Universidade Federal do Ceará, Fortaleza, 2015. / Submitted by Vitor Campos (vitband@gmail.com) on 2016-09-26T23:43:14Z No. of bitstreams: 1 2015_tese_fperlatti.pdf: 7190341 bytes, checksum: 1384a873edd02a706a01eb41b55a723f (MD5) / Approved for entry into archive by Jairo Viana (jairo@ufc.br) on 2016-09-26T23:46:34Z (GMT) No. of bitstreams: 1 2015_tese_fperlatti.pdf: 7190341 bytes, checksum: 1384a873edd02a706a01eb41b55a723f (MD5) / Made available in DSpace on 2016-09-26T23:46:34Z (GMT). No. of bitstreams: 1 2015_tese_fperlatti.pdf: 7190341 bytes, checksum: 1384a873edd02a706a01eb41b55a723f (MD5) Previous issue date: 2015 / The extraction and processing of metallic minerals generate large amounts of waste which, if not disposed of properly, may be sources of contamination and acid mine drainage; by contact of sulphides with water and oxygen; causing a decrease in pH and an increase in the mobility of metals in the soil. The diagnosis of biogeochemical behaviour of wastes can provide valuable information to discard and control the adverse effects of this kind of material, as well to support the adoption of more efficient measures of control and mitigation. This study had as general objective diagnose the impacts of waste disposal in an abandoned copper mine (Cu), as well to propose alternatives to mitigate the impacts and restore the environmental quality of the site, based on the hypothesis that such wastes can contaminate the soil with trace elements contained in minerals, and generate acid mine drainage, given the presence of sulphides exposed to weather conditions, hindering the natural regeneration of the ecosystem. The Chapter 1 provides an introduction to the theme, as well as a literature review. Chapter 2 presents a general diagnosis from the area, assessing the levels of several trace elements in rock wastes, soils and native plant species. In chapter 3, a thorough study on the geochemical behaviour of wastes, with focus on the generation of acid drainage were done, plus a detailed study about Cu behaviour in soils, through a chemical sequential extraction. Chapter 4 details the content of metals in above-ground tissues from plants that naturally grow on the wastes, assess the ability of these plants to be used in phytoremediation and show data about the changes that occur in the rhizosphere. Chapter 5 provides through a comparative study by sequential extraction in the rhizosphere and bulk soils; details about the changes that occur in the rhizosphere of plants and their consequences for Cu mobility and ecotoxicity, and finally, the chapter 6 presents an experimental study with the use of technosols, as way to immobilize the excess of labile copper in soil solution. Based on the results, can be concluded that the major impact is caused by the excess of Cu which still persists in the waste rocks and, through oxidation and dissolution processes, translocate large amount of metal into soil. The acid mine drainage was discarded given the buffering action generated by dissolution of carbonates, minimizing the negative effects of the oxidation of sulphides. The sequential extraction showed that the Cu concentration in soil is associated mainly with carbonates and amorphous iron oxides. The geochemical cycle between the dissolution of carbonates and oxidation of sulphides appears to be the main control mechanism of release and adsorption of Cu in soil. Regarding the plants, was concluded that they cannot be considered as Cu hyperaccumulators, however, high levels of metal were observed in roots, indicating that the survival strategy of these plants consists in immobilize metal in roots/rhizosphere. The sequential extraction in the rhizosphere showed that the presence of plants alter various soil characteristics under its influence, and also the geochemical behaviour of Cu. The technosols showed great ability to immobilize Cu. The four technosols elaborated in this study can immobilize more than 85% of Cu in solution, with the largest portion retained in the residual fraction, where Cu is adsorbed strongly, demonstrating that technosols emerge as an excellent alternative to remediate soils contaminated by metals. / A extração e beneficiamento de minerais metálicos geram grandes quantidades de rejeitos que se não dispostos adequadamente, podem ser fontes de contaminação e drenagem ácida; pelo contato de sulfetos com água e oxigênio; ocasionando diminuição no pH e aumento na mobilidade dos metais no solo. O diagnóstico do comportamento biogeoquímico de rejeitos pode fornecer informações valiosas para que se possa dispor e controlar adequadamente os efeitos adversos causados por esse tipo de material, bem como subsidiar a adoção de medidas de controle e mitigação mais eficientes. Esse estudo teve como objetivo geral, diagnosticar os impactos causados pela disposição de rejeitos em uma mina de cobre (Cu) abandonada, bem como propor alternativas para mitigar os impactos e restaurar a qualidade ambiental do local, baseado na hipótese de que esses rejeitos podem contaminar o solo da região com os elementos traço presentes nos minerais, além de gerar drenagem ácida, dada a presença de sulfetos expostos às condições atmosféricas, impedindo a regeneração natural do ecossistema. O capítulo 1 traz uma introdução ao tema, bem como uma revisão bibliográfica sobre o assunto. O capítulo 2 faz um diagnóstico geral da área, avaliando-se os teores de diversos elementos traço nos rejeitos, solos e plantas. No capítulo 3 foram aprofundados os estudos sobre o comportamento geoquímico dos rejeitos com foco na geração de drenagem ácida, além de um estudo detalhado do comportamento do Cu no solo, através da extração sequencial. O capítulo 4 detalha os teores de metais nos tecidos vegetais das plantas, avalia a aptidão do uso dessas espécies para a fitoremediação, bem como apresenta dados das alterações que ocorrem na rizosfera. O capítulo 5 aprofunda-se nas alterações que ocorrem na rizosfera das plantas e as consequências na mobilidade e ecotoxicidade do Cu, via extração sequencial, e por fim, o capítulo 6 apresenta um estudo experimental com a utilização de tecnosolos, para imobilizar o excesso de Cu lábil no solo. Os resultados indicam que o principal impacto é causado pelo excesso de Cu que ainda persiste nos rejeitos e que, por processos de oxidação e dissolução, translocam grandes quantidade do metal para o solo. A geração de drenagem ácida foi descartada; dada a ação tamponante gerada pela dissolução dos carbonatos, minimizando os efeitos negativos da oxidação dos sulfetos. A extração sequencial mostrou que o Cu no solo está associado principalmente aos carbonatos e óxidos de Fe amorfos. O ciclo geoquímico entre a dissolução dos carbonatos e oxidação dos sulfetos parece ser o principal mecanismo de liberação e adsorção do Cu no solo. Já as plantas estudadas, não foram consideradas hiperacumuladoras, entretanto, foram observados elevados teores de metal em suas raízes, indicando que a estratégia de sobrevivência dessas plantas consiste na imobilização do metal nas raízes/rizosfera. A extração sequencial na rizosfera mostrou que a presença das plantas altera as características do solo sob sua influência, e consequentemente o comportamento biogeoquímico do Cu. Já os tecnosolos demostraram grande capacidade em imobilizar Cu. Os quatro tecnosolos elaborados imobilizaram mais de 85% do Cu, sendo a maior parte retida na fração residual, que representa a fração onde o cobre fica adsorvido mais fortemente, demostrando que os tecnosolos despontam como uma excelente alternativa na remediação de solos contaminados por metais.
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Fonctionnement écologique des mares forestières temporaires naturelles et restaurées : Décomposition de la matière organique et relations interspécifiques / Ecological functioning of natural and restored vernal pools : Organic-matter decomposition and interspecific relationships

Hervé, Pauline 27 February 2018 (has links)
Les mares forestières temporaires sont de petites zones humides d’eau douce, sujettes à de fortes dégradations. Le fonctionnement des mares naturelles et restaurées a été étudié en se basant sur les taux de décomposition de la matière organique (MO) et sur l’effet de facilitation d’une plante vasculaire (Molinia caerulea, molinie) sur la croissance des sphaignes (Sphagnum palustre). Les taux de décomposition de la MO dans l’eau ne différaient pas entre les mares naturelles et restaurées mais ils étaient influencés par la teneur en carbone organique du sol, l’ouverture de la canopée forestière et le couvert en sphaignes. Dans le sol de la zone de transition mare-forêt, ces taux étaient réduits par la saturation en eau et par un couvert molinie-sphaignes. La présence de la molinie diminuait la croissance des sphaignes, suggérant une compétition. Les résultats de cette étude contribuent à l’écologie de la restauration de ces mares et questionnent leur devenir dans un contexte de changement climatique. / Vernal pools are small freshwater wetlands, subject to strong degradations. The functioning of natural and restored vernal pools was studied, based on organic matter (OM) decomposition rates and the facilitation effect of a vascular plant (Molinia caerulea, purple-moor grass) on Sphagnum growth (Sphagnum palustre). The rates of OM decomposition in water were not different between natural and restored pools, but they were influenced by soil organic carbon content, tree canopy openness and Sphagnum cover. In the soil of the pool-forest transition zone, these rates were reduced by water logging and by a Molinia-Sphagnum cover. The presence of Molinia decreased Sphagnum growth, suggesting a competition relationship. The results of this study contribute to the restoration ecology of vernal pools and raise the question of their fate in the climate change context.

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