• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 137
  • 52
  • 36
  • 14
  • 14
  • 7
  • 5
  • 5
  • 5
  • 5
  • 5
  • 5
  • 5
  • 2
  • 2
  • Tagged with
  • 335
  • 61
  • 36
  • 35
  • 31
  • 31
  • 28
  • 28
  • 28
  • 25
  • 25
  • 24
  • 23
  • 22
  • 20
  • 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.
211

Příprava přírodovědné naučné stezky Hluboká nad Vltavou - Zoo Ohrada / The preparation of an educational pathway Hluboka upon Vltava - Zoo Ohrada

SOCHOROVÁ, Jana January 2009 (has links)
The diploma thesis The preparation of an educational pathway Hluboka upon Vltava - Zoo Ohrada deals with compiling of the terrain in the neighbourhood of the Zoo Ohrada, subsequent creating of designs and texts for individual information boards. The Educational pathway is called, "On the dam of the Municky pond". The first part of the diploma thesis describes physical-geographical characteristics of the defined area and the history of building educational pathways in the Czech Republic, their types and classification. One chapter is devoted to building educational pathways and possibilities of their financing. The content of the second part of the diploma thesis is a design of the educational pathway itself, texts about individual stages, suggestions for an arrangement of information on information boards including visual documentation, their marking and realization. Scope of the boards is varied, they provide a lot of information about flora and fauna that can be found in this area and also information about natural and environmental regularities and relationships between organisms. A part of the diploma thesis is also a methodical guide with plenty of games, suggestions and activities to make the course of the educational pathway more interesting. The appendix of the diploma thesis contains fotodocumentation, maps and a set of worksheets wit a key.
212

Uppföljning av reningsfunktionen i Steningedalens våtmark / Follow-Up of the Water Purification Function at Wetland of Steningedalen

Girleviciute, Aiste January 2018 (has links)
Dagvattnet från Märsta är belastat med bland annat tungmetaller och näringsämnen. Vattnet hamnar i Märstaån och transporteras vidare ut till Mälaren. Steningedalens våtmark är ett dammsystem som renar och fördröjer en del av Märstaåns flöde före transport ut mot Mälaren.   Syftet med detta självständiga arbete på kandidatnivå har varit att undersöka anläggningens reningsfunktion med hjälp av sedimentprovtagning. Sedimentprover har tagits vid in- och utloppet och en kemisk analys av dessa har utförts i ett ackrediterat laboratorium. Resultaten från in- och utloppet har jämförts för att se om det sker en minskning av föroreningar genom systemet. Fem sedimentfällor har placerats ut i delar av dammsystemet för att undersöka sedimentfördelningen och muddringsbehovet i anläggningen. Resultatet av studien visade att dammsystemet har en god vattenreningsfunktion med avseende på tungmetallerna bly, nickel, kadmium, krom, koppar och zink samt näringsämnet fosfor. Anläggningen har bedömts att vara i behov av muddring. / In Märsta, the storm water is contaminated with heavy metals and nutrients (nitrogen and phosphorus) among other pollutants. The water emits to the river Märstaån and further to the lake Mälaren. The wetland of Steningedalen is a pond system that delays part of the stream in Märstaån and purifies the water on its way through the system. This independent project is based on investigation of the purification functioning at Steningedalen wetland. The investigation has been done by sediment sampling and analysis. The samples were taken from the inlet and the outlet of the pond system. Chemical analysis has been made on these samples in an accredited laboratory. The results were compared in order to see if there is a trend through the system. Five sediment traps were placed in parts of the system to study the distribution of the sediment and the need of dredging. The results of the study have concluded that the stormwater pond system has a good water purification function with regard to heavy metals lead, nickel, cadmium, chromium, copper and and zinc aswell as the nutrient phosphorous. The study has also shown that the system is in need of dredging.
213

Avaliação nutricional e de crescimento incial em altura de espécies arbóreas em sistemas agroflorestais na região de Itaparica, semiárido pernambucano / Nutritional assessment and initial height growth of tree species in agroforestry systems in the region of Itaparica, semiarid region of Pernambuco

SANTOS, Rubeni Cunha dos 29 February 2016 (has links)
Submitted by Mario BC (mario@bc.ufrpe.br) on 2016-07-08T13:47:04Z No. of bitstreams: 1 Rubeni Cunha dos Santos.pdf: 1742923 bytes, checksum: 953173bab6b47ea6b8b8c3ffecede71f (MD5) / Made available in DSpace on 2016-07-08T13:47:04Z (GMT). No. of bitstreams: 1 Rubeni Cunha dos Santos.pdf: 1742923 bytes, checksum: 953173bab6b47ea6b8b8c3ffecede71f (MD5) Previous issue date: 2016-02-29 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / This study developed at the Experimental IPA station in Belém de São Francisco - PE, surrounding the Itaparica Reservoir, in Pernambuco semiarid zone, aimed to evaluate the effect of using sediments from Itaparica reservoir and fish pond waste as organic fertilizers and biochar as a soil conditioner and the effect of two spacings, 3 x 2 m and 4 x 2 m, in stimulating the growth of four tree species: two Eucalyptus clones (Eucalytpus urophylla x Eucalytpus tereticornis) angico (Anadenanthera colubrina var. cebil) and aroeira (Myracrodruon urundeuva Allemão), associated or not in agroforestry systems with cowpea and in a silvopastoral system with Tanzania grass. It was used a multivariate statistical method of repeated measures over the time. Measurements were taken every three months after planting (0, 3, 6, 9, 12, 15 and 18 months) in the useful area of the plots (10 plants). The number of permanent plots was 256, distributed in a randomized pattern, with four repetitions, which included control without fertilization and isolated plantations. The two spacing were 4 x 2 m for tree species in the consortium and isolated and 3 x 2 m for the species forest isolated. it was collected samples of leaves for foliar analysis in newly mature harvested from the middle third of the canopy, to determine the nutritional status of four tree species, adopting a completely randomized design in a factorial arrangement 4 x 4 x 2, for the isolated and consortium plantation. The fertilization of the species with organic sources of nutrients at the time and after planting resulted in better growth of tree species and improved the nutritional status of the species, especially in relation to nitrogen. The residues from fish farms ponds and lake sediments appear as good alternatives to fertilization in agroforestry systems, as well as in forestry and agriculture. The smallest spacing (3m x 2m) resulted in higher growth of forest species. Native species (angico and aroeira) appeared to have higher nutritional requirement and, in general, had higher levels of nutrients in the leaves compared to Eucalyptus clones. The nutritional content found in leaves, in different spacing and consontium for angico, aroeira and the clone MA 2000 followed the decreasing order: N> Ca> P> Mg and for clone MA 2001 the sequence was N> Ca> Mg> P. For the different consortia, the sequence for all the species was N> Ca> P> Mg. Consortia with agricultural species and the forage species did not affect height growth of forest species and added value to forest production. / O presente estudo desenvolvido na Estação Experimental do IPA, em Belém do São Francisco - PE, no entorno da Represa de Itaparica, no semiárido pernambucano, objetivou avaliar o efeito do uso de sedimentos do reservatório de Itaparica, resíduos de tanques de piscicultura como fertilizantes orgânicos e do biocarvão como condicionador de solo e o efeito de dois espaçamentos, 3 x 2 m e 4 x 2 m, no estímulo ao crescimento de quatro culturas florestais: dois clones de eucalipto (Eucalytpus urophylla x Eucalytpus tereticornis.), angico (Anadenanthera colubrina var. cebil) e aroeira (Myracrodruon urundeuva Allemão), consorciados ou não em sistemas agrossilvicultural com feijão caupi e em sistema silvipastoril com capim Tanzânia. Utilizou-se o método estatístico multivariado de medidas repetidas de altura a cada três meses após o plantio (0, 3, 6, 9, 12, 15 e 18 meses). O número de parcelas permanentes foi 256, distribuídas de forma inteiramente aleatória, com 4 repetições, que incluíram testemunhas sem adubação e plantios isolados, sendo o espaçamento 4 x 2 m para as culturas florestais em consórcio e isolado e 3 x 2 m para as culturasflorestais em plantio isolado. Usou-se área útil de coleta dos dados com 10 plantas por parcela. Foram feitas análises foliares em folhas recém-maturas colhidas do terço médio da copa, para determinação do estado nutricional das quatro culturas arbóreas, adotando-se o delineamento inteiramente casualizado no esquema fatorial 4 x 4 x 2, para o plantio isolado e para o plantio em consórcio. A adubação das plantas com as fontes orgânicas de nutrientes no momento e após o plantio resultou melhores crescimentos das culturas florestais e melhorou o seu estado nutricional, principalmente em relação ao nitrogênio, sendo que os resíduos de tanques de piscicultura e sedimentos do lago surgem como boas alternativas para adubação em sistemas agroflorestais, bem como em silvicultura e em agricultura. O menor espaçamento (3 m x 2 m) resultou maior crescimento das culturas florestais. As espécies nativas (angico e aroeira) aparentaram maior requerimento nutricional e, em geral, tinham maiores teores de nutrientes nas folhas, em comparação aos clones de eucalipto. Os teores nutricionais encontrados nas folhas, nos diferentes espaçamentos e consórcios, de angico, aroeira e clone MA 2000 seguiram a sequência decrescente: N > Ca > P > Mg e os teores foliares para o Clone MA 2001 apresentaram a sequência N > Ca > Mg > P, enquanto que, nos diferentes consórcios, a sequência dos teores foliares de todas culturas florestais foi N > Ca > P > Mg. Os consórcios com a espécie agrícola e a espécie forrageira não afetaram negativamente o crescimento em altura das espécies florestais e agregaram valor à produção florestal.
214

Bioensaio toxicológico com cianobactérias do efluente da lagoa de estabilização e do Igarapé Grande, Boa Vista, Roraima

Eliana Fernandes Furtado 28 March 2011 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / A pesquisa teve o objetivo de averiguar a presença de toxicidade nas cianobactérias planctônicas no deságue da Lagoa de estabilização no igarapé Grande, em Boa Vista, por meio de bioensaio em camundongos de linhagem Swiss albino. O corpo hídrico em estudo está localizado na área urbana de Boa Vista, recebe influência resultante da descarga final dos esgotos domésticos dos moradores próximos e de efluentes do sistema de tratamento de esgotos sanitários da cidade, apresentando florações em alguns trechos. Pesquisas anteriores constataram a presença de florações de cianobactéria planctônica nesse ambiente. No entanto, havia a ausência de estudos sobre a toxicidade das florações de cianobactéria planctônicas existentes no igarapé Grande. A área escolhida foi georeferenciada e denominada como: E1 (montante do deságue da ETE), situada no igarapé grarde; E2 (desague/calha); E3 (jusante do deságue). Foram realizadas três coletas amostrais no período seco e três no período das chuvas. No momento da coleta, foram feitas medidas do pH e temperatura da água. Em seguida, foram realizadas as análises das concentrações de clorofila-a, nitrogênio amoniacal, fósforo total, turbidez e estimativa de densidade celular. Foi observado a presença de cianobactérias da espécie Planktothrix agardhii (Gomont) Anagnostidis et Komárek durante todos os meses de coletas, nos períodos sazonais (seco e chuvoso) e confirmou-se que a Estação de Tratamento de Esgoto Sanitário do município de Boa Vista ETE/BV - é a fonte de entrada dessa espécie de cianobactéria no igarapé Grande. Foi observada a distribuição dos organismos na superfície da água afetando a qualidade físico-química do igarapé Grande. Também o teste estatístico possibilitou a identificação da amônia (NH3) como a variável de maior contribuição para a toxicidade nas estações. Além disso, o resultado foi ratificado pelos testes quimiométricos PCA; FA. O teste (DL50 -24 horas), realizado por meio de bioensaio em camundongos no período seco, do material algáceo da estação E3, apresentou a toxicidade em doses acima de 2.500 mg kg mL- (p.c), com a maior mortalidade de 75% dos indivíduos do grupo que recebeu as concentrações de 100 mg mL-. Os resultados da estação de coleta E2, mostram mortalidade de 25% dos indivíduos na concentração de extrato de 50 mg mL-, 25% de indivíduos e 100 mg mL- dos individuo e 75% de indivíduos com a concentração de 150 mg mL- das amostras coletadas durante o período das chuvas. / The study aimed to access the presence of toxic planktonic cyanobacteria by mouse bioassay in the outflow of the stabilization pond and in the Igarapé Grande, Boa Vista, RR. The waterbodies under study are located in the urban area of Boa Vista, and are influenced by the final discharge of the domestic sewage from nearby residents and effluents of the sewage treatment plant from the city. Previous research has established the presence of cyanobacterial blooms in this environment. However, there was a lack of studies on the toxicity of the cyanobacteria that bloom in the stabilization pond system and adjacent Igarapé Grande. The study area was geo-referenced and named as E1 (upstream of the sewage treatment plant outflow), located in the Igarapé Grande, E2 (outflow/gutter), and E3 (downstream of the outflow), also in the Igarapé Grande. It was performed three sample collections during the dry season and three during the rainy season. At the time of the samplings measurements of pH and water temperature were carried out. It was also collected samples for the estimation of chlorophyll-a, ammonia nitrogen, total phosphorus, turbidity and cell density evaluation. We observed the presence of the cyanobacteria of the genus Planktothrix agardhii during all the sampled months in both seasons (dry and rainy), confirming the city sewage treatment plant as the main source of entry of this species in the Igarapé Grande. It was also confirmed that the distribution of the organisms on the water surface affects the physico-chemical quality of the Igarapé Grande. Statistical analysis enabled the identification of ammonia as the parameter of greatest contribution to the toxicity in the sampled locations. In addition, confirmation was obtained by the chemometric tests PCA, FA, HCA and PLS. The mouse bioassay tests (LD50 - 24h) showed toxicity at doses above 2,500 mg.Kg-1 b.w. and at concentrations of cell extract over 50 mg mL-. The higher mortality occurred in 75% of individuals in the group that received concentrations of 100 mg mL- of the material collected at E3 during the dry season. The results of E2 sampling station showed mortality of 25% of individuals at extract concentration of 50 mg mL-; 25% of individuals at 100 mg mL- and 75% of individuals at concentration of 150 mg mL- from the samples collected during the rainy season.
215

Avaliação da atividade microbiana metanogênica na lagoa de estabilização anaeróbia da estação de tratamento de esgotos sanitários do município de Cajati, Vale do Ribeira do Iguape, Estado de São Paulo / Assessment of anaerobic methanogenic microbial activity at anaerobic stabilization pond of domestic wastewater plant at Cajati city, Vale do Ribeira de Iguape, São Paulo State, Brazil

Lara Steil 31 August 2007 (has links)
O estudo sobre a comunidade microbiana de um sistema de tratamento biológico de águas residuárias é de particular interesse, uma vez que o conhecimento da microbiologia do processo pode levar ao aperfeiçoamento de projetos e ao aumento da eficiência dos sistemas. Este trabalho avaliou a atividade microbiana, particularmente a metanogênica, na lagoa de estabilização anaeróbia da estação de tratamento de esgotos sanitários do município de Cajati - SP. Para isso adotou a taxonomia polifásica na caracterização dos microrganismos e de seus aspectos funcionais, buscando o conhecimento da diversidade dos microrganismos e suas relações nesse tipo de sistema anaeróbio. Objetivou também contribuir para o estabelecimento de um protocolo seguro na realização dos ensaios de atividade metanogênica específica (AME). Os estudos foram realizados com amostras dos sedimento da lagoa coletadas em três períodos diferentes, a saber: outubro/2003, outubro/2004 e dezembro/2004. Durante as amostragens foram determinadas variáveis abióticas como temperatura, condutividade, pH, potencial de óxido-redução e teor de oxigênio dissolvido. Medidas do conteúdo de sólidos totais e voláteis (SV) foram também realizadas. A avaliação da atividade microbiana foi feita por exames microscópicos de contraste de fase e fluorescência, AME, determinação do DNAtotal, FISH - hibridização in-situ com sondas fluorescentes e DGGE - eletroforese em gel com gradiente linear de agentes desnaturantes. Também procedeu-se a contagem de protozoários e análise da presença de algas e cianobactérias. Os resultados revelaram que ocorreu variação nas condições do processo biológico nos períodos amostrados, sendo que em outubro/2004, durante período de fortes chuvas e ventos, a eficiência na redução da DBO foi apenas 18,2%. Nesse período, constatou-se organismos como algas do gênero Chorella sp e cianobactérias do gênero Merismopedia sp. Nas demais coletas a remoção da matéria orgânica medida em DBO foi superior a 80%, com boa atividade anaeróbia. Os resultados mostraram que a relação So/Xo de 0,25 gDQO/g SV foi a mais adequada para determinar o valor de AME, e os ensaios com as amostras de outubro/2003 e dezembro/2004 revelaram valores de AME na faixa de 0,85 a 0,21 mg\'CH IND.4\'/gSV.d. Constatou-se a ocorrência de alterações na estrutura da comunidade microbiana inicial em relação à final do experimento de AME, por meio do DGGE. Verifcou-se também nesses ensaios, que o conteúdo de SV inicial variou entre amostras e substratos, conferindo alta variabilidade ao teste. Os perfís de DGGE das amostras coletadas revelaram variação na estrutura das comunidades microbianas no sedimento, e maior diversidade de bactérias e arquéias quando a lagoa anaeróbia apresentava boa eficiência na redução da DBO. A técnica FISH como adotada não foi eficaz para quantificar e identificar os microrganismos devido ao excesso de hibridizações inespecíficas. Mesmo com suas limitações, a técnica FISH revelou a presença de microrganismos dos Domínios Bacteria e Archaea. Nesse caso, a Família Methanobacteriaceae, a ordem Methanomicrobiales e o gênero Methanosaeta sp. foram confirmados. Nas diferentes coletas, foram identificados protozoários dos gêneros Paramecium sp. e Vorticella sp., e rotíferos dos gêneros Brachionus sp., Trichocerca sp., Synchaeta sp. e Keratella sp. / Microbial diversity studies have remarkable relevance since the knowledge about the microbiology of process can improve plants and system efficiency. This work assessed microbial activity, specially methanogenic, at anaerobic pond for domestic wastewater treatment in the city of Cajati, São Paulo State, Brazil. Poliphasic taxonomy was adopted in onder to contribute to the understanding of microbial community diversity and functionality. As well as to contribute for the establishment of a protocol to the specific methanogenic activity test (SMA). Three periods of sampling were done at the sediment of the anaerobic pond (october 2003, october 2004 and december 2004). Abiotic variables as temperature, conductivity, pH, dissolved oxygen and redox potential were measured at sampling time. TS and VS contents were determined in the samples. Microbial studies were done by observation on optical and fluorescent microscopy, analyse of SMA, totalDNA quantitation, counting of protozoa, analyze of algal and cyanobacteria presence, as well as application of two molecular techniques: Fluorescent in-situ Hybridization (FISH) and Denaturing Gradient Gel Electrophoresis (DGGE). Results showed that general conditions of the anaerobic pond changed among samplings. On October 2004, when the rain and wind were very strong, the organic matter removal efficiency (BOD basis) in the anaerobic pond was low (18.2%) and predominant microorganisms were of aerobic algae, as Chorella sp, and the blue-green algae Merismopedia sp. On the other hand, the removal of organics at other two samplings was more than 80% and the anaerobic microbial activity was verified in the sample. SMA tests showed the food/microorganism rate (F/M) of 0.25 gDQO/g VS was the most suitable to the samples. The results showed SMA values between 0.85 and 0.21 mg\'CH IND.4\'/gVS.d for samples of October 2003 and October 2004. SMA test induced modifications in the structure of the microbial community according to DGGE-profile. In addition, VS content, which was used in the SMA tests as biomass measurement, displayed variable behavior making test results difficult to interpret in some situations. DGGE-profile showed variation in the sediment community structure. Higher bacterial and archaeal diversity was observed when anaerobic pond showed 80%, or more, of DBO removal. FISH technique was not a suitable method to secure quantification and identification of the microorganisms from in excess. In spite of the technique limitations, it was possible to identify microorganisms of Bacteria Domain, Archaea Domain, Methanobacteriaceae Family, Methanomicrobiales Order, and microorganisms belonging to Methanosaeta genus. Paramecium and Vorticella were the protozoans identified in all samplings. Rotifers belonging to genders Brachionus, Trichocerca, Synchaeta and Keratella were also observed.
216

Polyculture crevette Litopenaeus stylirostris (Stimpson, 1974) et poisson Siganus lineatus (Valenciennes, 1835) : faisabilité technique et effets sur le fonctionnement écologique des bassins d'élevage de crevettes / Polyculture blueshrimp Litopenaeus stylirostris (Stimpson, 1974) and rabbitfish Siganus lineatus (Valenciennes, 1835) : technical feasibility and effects on the ecological functioning of shrimp ponds

Luong, Cong trung 21 July 2014 (has links)
L’aquaculture de la crevette bleue Litopenaeus stylirostris représente une activité profitable enNouvelle-Calédonie. Cependant, elle doit faire face à deux maladies bactériennes saisonnières quidiminuent les rendements et menacent le développement aquacole. D'après la littérature, lapolyculture avec des poissons pourrait diminuer l'occurrence des maladies, prévenir la dégradation del'environnement et au final augmenter la production des bassins. Cette étude porte sur la faisabilitéd'élever en bassins L. stylirostris avec Siganus lineatus. Les objectifs majeurs ont été 1) d’estimer lacapacité de S. lineatus à s’adapter aux bassins et d’évaluer les performances de croissance, 2)d’estimer la faisabilité technique de la polyculture de L. stylirostris avec S. lineatus et 3) d’estimer leseffets de cette polyculture sur les performances zootechniques des deux espèces et sur lefonctionnement écologiques des bassins par comparaison avec leur monoculture.Pour répondre au premier objectif, Siganus lineatus (5.7g) a été mis en culture à des densités de 7, 14et 21 poissons.m-2 en système clos. Après 8 semaines de culture, les performances de croissance de S.lineatus ont été similaires quelles que soient les densités. S. lineatus peut donc bien s’adapter etcroître dans ces systèmes clos, même à des températures basses, proches de 20°C, et à forte densité.Les fortes densités n’ont pas eu d’effets négatifs sur la croissance, mais sont à l’origine d’unedétérioration des conditions environnementales suite à un apport plus marqué en aliment générantdavantage de déchets organiques. En conséquence, une mortalité de S. lineatus peut apparaître lorsquela concentration en oxygène descend en dessous des 2 mg.L-1.Pour atteindre le 2ème et le 3ème objectif, une seconde expérience a montré que l’ajout de S. lineatus(25.5 g) à une culture de crevettes (2.9 g; 15 crevettes.m-2) à des densités de 0, 1.2 et 2.4 poissons.m-2n’a pas affecté les performances zooetchniques de L. stylirostris sur cette première phase d'élevage.La survie de S. lineatus a été de 100% et sa croissance a été similaire quelle que soit sa densité. Laproduction combinée totale pour les traitements polyculture a augmenté de 47 – 106 % et les indicesde conversions diminuent de 31.6 – 47.7% en comparaison avec le traitement "monoculture decrevettes". L'ajout de S. Lineatus n'a pas eu d'effets significatifs sur la production primaire, larespiration, les flux dissous et particulaires à l'interface eau-sédiment de l'écosystème bassin.Dans une troisième expérience, avec des biomasses initiales plus élevées de L. stylirostris (14 g) de156 g.m-2 en polyculture avec S. lineatus (19 g) (80 g.m-2) et de 237 g.m-2 en monoculture, nous avonsobservé une forte mortalité des crevettes. Inversement, avec des biomasses initiales de S. lineatus (19g) de 155 g.m-2 en polyculture avec L. stylirostris (14 g) (81 g.m-2) et de 235 g.m-2 en monoculture,nous avons montré une augmentation de la biomasse de S. lineatus. En utilisant l'aliment pour sapropre croissance non utilisé par les crevettes, S. lineatus est ainsi capable de limiter l'impact dû àl'eutrophisation de l'écosystème bassin.Les résultats des analyses isotopiques montrent que l'aliment n'est pas une source majeure de carbonepour L. stylirostris et S. lineatus alors qu'il l'est pour l'azote. Le biotope, en y incluant la matièreorganique des sédiments et la matière organique particulaire dans la colonne d'eau est la principalesource de carbone pour les deux espèces et une source secondaire pour l'azote.Pour conclure, S. lineatus est un candidat potentiel pour la culture commerciale / Blue shrimp Litopenaeus stylirostris farming is a major and profitable activity of aquaculture industryin New Caledonia. However, it is facing two seasonal bacterial diseases, which decrease rearedshrimp yield and threaten the sustainability of the aquaculture development. As reported by theliterature, polyculture with fish would have the potential to decrease the impact of these kind ofdiseases, prevent the deterioration of the environment and to increase the production of the ponds. Thefeasibility of L. stylirostris and Siganus lineatus polyculture in earthen ponds was carried out in thisstudy. The main objectives were 1) to estimate the adaptive capacity and growth performance of S.lineatus, and the environmental variations in a closed culture system, 2) to estimate the technicalfeasibility of L. stylirostris and S. lineatus polyculture, and 3) to estimate the effects of L. stylirostrisand S. lineatus polyculture on zootechnical performances and pond ecology in comparison withmonoculture of these species.To answer to the first objective, Siganus lineatus (5.7g) was stocked at 7, 14 and 21 fish.m-2 in aclosed culture system. After 8 weeks of culture period, S. lineatus growth performance was similarbetween all densities. S. lineatus could well adapt and grow in a closed system, even at lowtemperature, ca. 20oC and high stocking density, 21 fish.m-2. High stocking density did not havenegative effects on S. lineatus growth performance, but could cause the environmental deteriorationdue to increased nutrient input and accumulated organic wastes in the culture system. Asconsequence, S. lineatus could die when water oxygen depleted to below 2 mg.L-1.To reach the second and the third objective, a second experiment showed that adding S. lineatus (25.5g) to L. stylirostris (2.9 g) culture system (15 shrimp.m-2) at 1.2 and 2.4 fish.m-2 did not affect L.stylirostris zootechnical performance during the first stage of the rearing. S. lineatus gained 100% ofsurvival and similar growth performance in all densities. The polyculture system increased totalcombined production by 47 – 106 % and reduced FCR by 31.6 – 47.7% compared with those inshrimp monoculture. The addition of S. lineatus to the culture system did not have significantlyeffects on the gross primary productivity, the respiration, the nutrient and particulates fluxes at thewater-sediment interface of the pond ecosystem.In a third experiment, using higher stocking biomasses of L. stylirostris (14 g) at 156 g.m-2 in apolyculture with S. lineatus (19 g) (80 g.m-2) and at 237 g.m-2 in shrimp monoculture, we observed ahigh shrimp mortality. Conversely, stocking biomasses of S. lineatus (19 g) at 155 g.m-2 in apolyculture with L. stylirostris (14 g) (81 g.m-2) and at 235 g.m-2 in monoculture resulted in increasesof S. lineatus biomasses. This study showed that polyculture using S. lineatus is able to reduce organicwastes and nutrient release by consumption uneaten feed and retention input nutrients in biomass thatcontribute to limit the impact of the pond ecosystem eutrophication.Results of stable isotope analyses showed that the used pellet feed was not a major carbon source, butwas an important nitrogen source for both L. stylirostris and S. lineatus. Natural biota, includingsediment organic matter and particulate organic matter, was a main carbon source and represented asa secondary nitrogen source for both species.It may be concluded that S. lineatus is a suitable candidate for commercial culture in bothmonoculture and polyculture with L. stylirostris in earthen pond. Polyculture should be a properapproach that could partly contribute to sustainable development of aquaculture, but needs specificresearch to optimize the trophic status of the reared species.
217

Estimating Arctic sea ice melt pond fraction and assessing ice type separability during advanced melt

Nasonova, Sasha January 2017 (has links)
Arctic sea ice is rapidly declining in extent, thickness, volume and age, with the majority of the decline in extent observed at the end of the melt season. Advanced melt is a thermodynamic regime and is characterized by the formation of melt ponds on the sea ice surface, which have a lower surface albedo (0.2-0.4) than the surrounding ice (0.5-0.7) allowing more shortwave radiation to enter the system. The loss of multiyear ice (MYI) may have a profound impact on the energy balance of the system because melt ponds on first-year ice (FYI) comprise up to 70% of the ice surface during advanced melt, compared to 40% on MYI. Despite the importance of advanced melt to the ocean-sea ice-atmosphere system, advanced melt and the extent to which winter conditions influence it remain poorly understood due to the highly dynamic nature of melt pond formation and evolution, and a lack of reliable observations during this time. In order to establish quantitative links between winter and subsequent advanced melt conditions, and assess the effects of scale and choice of aggregation features on the relationships, three data aggregation approaches at varied spatial scales were used to compare high resolution satellite GeoEye-1 optical images of melt pond covered sea ice to winter airborne laser scanner surface roughness and electromagnetic induction sea ice thickness measurements. The findings indicate that winter sea ice thickness has a strong association with melt pond fraction (fp) for FYI and MYI. FYI winter surface roughness is correlated with fp, whereas for MYI no association with fp was found. Satellite-borne synthetic aperture radar (SAR) data are heavily relied upon for sea ice observation; however, during advanced melt the reliability of observations is reduced. In preparation for the upcoming launch of the RADARSAT Constellation Mission (RCM), the Kolmogorov-Smirnov (KS) statistical test was used to assess the ability of simulated RCM parameters and grey level co-occurrence matrix (GLCM) derived texture features to discriminate between major ice types during winter and advanced melt, with a focus on advanced melt. RCM parameters with highest discrimination ability in conjunction with optimal GLCM texture features were used as input parameters for Support Vector Machine (SVM) supervised classifications. The results indicate that steep incidence angle RCM parameters show promise for distinguishing between FYI and MYI during advanced melt with an overall classification accuracy of 77.06%. The addition of GLCM texture parameters improved accuracy to 85.91%. This thesis provides valuable contributions to the growing body of literature on fp parameterization and SAR ice type discrimination during advanced melt. / Graduate / 2019-03-21
218

Fosforsläpp och vigg i polerdamm vid Västra strandens avloppsreningsverk i Halmstad

Hansson, Ulf January 2017 (has links)
During the winters in recent years Laholmsbuktens VA's treatment plant in Halmstad has recorded unexcepted levels of phosphorus from the polishing pond. Only between 8 and 20 January 2016 samples indicates a realese of net 75 kg. In winter the pond temperature never goes below about 8oC, which attracts wintering waterfowl. In February 19, 2016 the largest number of birds in the inventory for this thesis was noted, 325 individuals, of which 208 were tufted ducks.  Even if the number of waterfowl at peak levels was to be about 1000 individuals, their combined contribution of phosphorus through droppings into the pond could not be more than 500 g per day. This study proposes that a significant factor is the foraging activity of tufted ducks, which are diving ducks. In search of food at daytime they disturb the sediment at the bottom of the pond, i.e bioturbation.  The higher proportion of particle-bound phosphorus in samples with high phosphorus content also fits well with this hypothesis. A scientific investigation in which the bottom of this part of the pond was stirred up mechanically gave similar proportions between phosphorus and water-soluble phosphorus.
219

Ressources secondaires de métaux, valorisation par voie hydrométallurgique de résidus de sidérurgie pour la valeur en zinc, en manganèse et plomb / Secondary metal sources, recovery of zinc, manganese and lead from pyrometallurgical sludge by hydrometallurgical processing

Mocellin, Julien 10 December 2015 (has links)
Entre le milieu du XIXème et du XXème siècle, le secteur sidérurgique a été l’une des principales sources de richesse en France. Toutefois, la production de ferromanganèse a généré une quantité considérable de déchets, notamment lors du lavage des fumées des hauts fourneaux. Ces boues d’épuration, riches en zinc (Zn), manganèse (Mn) et plomb (Pb) (5 à 40% en masse), ont été déposées dans des bassins de décantation en périphérie des sites sidérurgiques. Depuis la fermeture des usines, ces terrains sont restés en l’état et certains, comme à Pompey (Lorraine), ont été progressivement colonisés par la végétation. Compte tenu des risques sanitaires liés aux concentrations en métaux, une décontamination semble inévitable. Néanmoins, on prend conscience aujourd’hui de l’épuisement des ressources, et ces bassins apparaissent comme un gisement de ressources secondaires. Ce travail vise à développer un procédé hydrométallurgique pour extraire Zn, Mn et Pb de ces résidus, dans l’optique de récupérer ces métaux sous forme pure et revalorisable, tout en décontaminant ces sites. Tout d’abord, les expériences ont permis déterminer les conditions optimales (quantité d’acide, temps, température, ajout de réactifs, densité de pulpe) pour parvenir à extraire sélectivement Zn et Mn contenus dans les boues et former un résidu riche en Pb. Le Zn a été ensuite récupéré sous forme de ZnO ou ZnS par précipitation ou sous forme métallique par électrodéposition. Enfin, le Mn a été précipité sous forme de MnCO3 avec une concentration acceptable en impuretés. Une étude technico-économique a été réalisée pour évaluer l’intérêt de l’industrialisation du procédé / During the XIXth and XXth centuries, steel industry has been one of the main sources of wealth in France. However, ferromanganese manufacturing has produced huge quantities of wastes, for instance after blast-furnace gas washing. The residual sludge, containing high concentrations of zinc (Zn), manganese (Mn) and lead (Pb) (5 to 40 wt %), has been deposited in ponds, in the vicinity of steel-making plants. Since plant closure, these fields have been left untouched; some of them, like in Pompey (Lorraine) have been colonized by vegetation. These sites may be considered as a threat to health and environment and should be cleaned up. Nevertheless, with awareness of metal shortage, these ponds may be considered as deposits of secondary resources. This works aims at designing a hydrometallurgical process to extract Zn, Mn and Pb from these residues and recover them in a valuable form, while decontaminating the sites. At first, experiments have enabled us to determine the optimal conditions (acid concentration, duration, temperature, reactant addition, pulp density) to extract selectively Zn and Mn from the sludge and leave a Pb-rich residue. Then, Zn was recovered as ZnO or ZnS after precipitation or as Zn after electrowinning. Mn was recovered as MnCO3 at an acceptable purity. A technico-economic study has been done to assess the industrial interest of the process
220

Návrh malé vodní nádrže s retenčním účinkem v katastrálním území obce Police. / Retention Reservoir Design in the Police Cadastr

Hadaš, Zdeněk January 2014 (has links)
This thesis deals with the river basin flood protection Loučka. The goal of the thesis is to assess the need of flood control measures supplement in the watershed. The first part deals with exploration of river basin, acquiring geographic factors and obtaining information about the topic, establishment and application of rainfall model used for solving the problem. The second part deals with improving of flood protection at critical selected places by using design of reservoir system with retention effect and by increasing river basin capacity. For basin schematisation was used ArcGIS program and the simulation of rainfall-runoff process was made by Hydrog program.

Page generated in 0.0541 seconds