O presente trabalho avaliou o efeito da relação \'C\'/\'N\' na produção biológica de hidrogênio a partir de água residuária sintética a base de sacarose. Reatores de leito fixo e fluxo ascendente, com polietileno de baixa densidade reciclado para adesão da biomassa, foram operados a 25°C e com um tempo de detenção hidráulica (TDH) de 2 horas. Analisaram-se diferentes relações \'C\'/\'N\' (40, 90, 140 e 190), usando a sacarose e a uréia como fontes de carbono e nitrogênio, respectivamente. Os valores médios de produtividade de \'H IND.2\' foram de 0,6 mol-\'H IND.2\'/mol-sac, 1,3 mol-\'H IND.2\'/mol-sac, 2,2 mol-\'H IND.2\'/mol-sac e 1,7 mol-\'H IND.2\'/mol-sac quando operados os reatores com relações \'C\'/\'N\' iguais a 40, 90, 140 e 190, respectivamente. Encontrou-se um valor ótimo para \'C\'/\'N\' de 137, que resultaria em produtividade de \'H IND.2\' de 3,5 mol-\'H IND.2\'/mol-sac, valor igual ao alcançado na relação \'C\'/\'N\' de 140. O biogás produzido foi composto de \'H IND.2\' e \'CO IND.2\', com valores médios porcentuais para o \'H IND.2\' de 53%, 49%, 61% e 52% para as relações \'C\'/\'N\' de 40, 90, 140 e 190, respectivamente. Os principais produtos intermediários produzidos durante a produção de \'H IND.2\' foram similares em todas as relações \'C\'/\'N\', sendo principalmente detectados ácido acético, ácido butírico e etanol. Sob excesso de nitrogênio, o crescimento da biomassa foi maior com efeitos negativos sobre a produção de hidrogênio, enquanto carência de nitrogênio permitiu o controle do crescimento da biomassa e resultou em maiores produtividades de hidrogênio. Durante os experimentos observou-se queda na produção do biogás provavelmente por atuação de bactérias hidrogênio-oxidantes. / This study evaluated the effect of the carbon/nitrogen (\'C\'/\'N\') ratio on the hydrogen production from a sucrose-based synthetic wastewater. Up-flow fixed-bed anaerobic reactors with recycled low-density polyethylene for biomass attachment, were operated at 25ºC and with a 2 hours time of hydraulic detention. Several \'C\'/\'N\' relationship were studied (40, 90, 140 and 190), using sucrose and urea as carbon and nitrogen sources, respectively. The average value of the hydrogen productivity were 0,6 mol-\'H IND.2\'/mol-suc, 1,3 mol-\'H IND.2\'/mol-suc, 2,7 mol-\'H IND.2\'/mol-suc e 1,7 mol-\'H IND.2\'/mol-suc they were reached when the reactors were operated with \'C\'/\'N\' of 40, 90, 140 and 190, respectively. It was found an optimal value for \'C\'/\'N\' of 137, which would result in productivity of 3,5 mol-\'H IND.2\'/mol-suc, an amount equal to that achieved in the \'C\'/\'N\' relationship of 140. Biogas produced was composed of \'H IND.2\' and \'CO IND.2\', with average \'H IND.2\' content 53%, 49%, 61% and 52% for \'C\'/\'N\' of 40, 90, 140 e 190, respectively. The mainly intermediary products during \'H IND.2\' fermentation were similar for all the \'C\'/\'N\' ratios, being specially detected acetic acid, butyric acid and ethanol. Under excess of nitrogen the biomass growth is higher with negative effects on hydrogen production while deprivation of nitrogen permits the control of biomass growth and results in higher hydrogen productivity. During the experiments it was been observed decline in the biogas production, probably because of the action of the hydrogen-oxidizing bacteria.

No description available.

Food web structure is of underlying importance to ecological functions and processes. Whilst it is understood that a range of biotic and abiotic factors affect structure, relatively little is known of the role of biodiversity per se in structuring food webs. In this thesis I utilise novel multi-dimensional estimates of food web structure based on stable isotope ratios of nitrogen (δ15N) and carbon (δ13C) to quantify structural responses to changing community diversity. I additionally investigate methodological aspects of sample preparation and stable isotope quantifications of food chains. Using an arthropod prey-predator system, in chapter 2 I demonstrate that tissue selection and lipid extraction are important methodological procedures for deriving accurate δ15N and δ13C signatures. In chapter 3 I test the utility of δ15N to quantify food chain length, and δ13C to trace primary energy sources through to end consumers. Bayesian resampling of variance in sample means for plant and arthropod food chains produces robust isotopic estimates that match known food chain length well despite some error variance, and estimates of δ13C-range that trace trophic transfers. Chapter 4 represents a change in system from lab to field as I determine δ15N and δ13C signatures for plant and invertebrate species within three grassland communities representing a gradient of biodiversity. Quantifications of community bivariate isotopic space using isotopic metrics revealed that greater taxonomic richness increased both diversity of resource space exploited and overlap in resource space. These results therefore suggest that loss of diversity affected structure through altering relative patterns of niche partitioning in resource exploitation amongst community members. In chapter 5, I additionally find evidence that grassland management mediated changes in food web compartmental structure that were associated with differences in generalist invertebrate predator feeding habits. Taken together, these findings develop and demonstrate the utility of isotopic approaches to quantifying food web structure, and provide evidence of important mechanisms by which biodiversity affects food web structure. I conclude that the preservation of natural food web structure and trophic dynamics are further reasons for halting loss of biodiversity.

The main subject of this thesis is a practical elaboration of the subject "Boron, Carbon and Nitrogen Group of the p-block elements" in form of presentations created using the Microsoft PowerPoint program. The presentations are designed to be used in practice, during the education of chemistry at secondary schools. The thesis also contains additional comments for teachers and an analysis of curricular documents and selected textbooks. It is elaborated in accordance with the RVP G programme.

Thesis (M.A.)--State University of New York at Binghamton, Department of Anthropology, 2006. / Includes bibliographical references.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2016-10-11T18:28:05Z No. of bitstreams: 1 renatotavaresmartins.pdf: 705337 bytes, checksum: 9a97dabab406750234e7a49e73457b79 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2016-10-22T12:51:26Z (GMT) No. of bitstreams: 1 renatotavaresmartins.pdf: 705337 bytes, checksum: 9a97dabab406750234e7a49e73457b79 (MD5) / Made available in DSpace on 2016-10-22T12:51:26Z (GMT). No. of bitstreams: 1 renatotavaresmartins.pdf: 705337 bytes, checksum: 9a97dabab406750234e7a49e73457b79 (MD5) Previous issue date: 2009-02-19 / O presente estudo foi composto por dois experimentos, o objetivo do primeiro deles verificar a colonização de Oligochaeta ao longo da decomposição da macrófita Eichhornia azurea (Sw.) Kunth, no segundo experimento, analisou-se a estrutura faunística dos macroinvertebrados no decorrer da decomposição de E. azurea e Salvinia auriculata Aubl. O experimento 1 foi dividido em dois períodos (1º período: setembro a novembro de 2007; 2º período: fevereiro a abril de 2008), em cada um deles, 21 sacos de náilon contendo 10 g de folhas de E. azurea, foram colocados no lago, e retirados após 2, 5,8, 12, 25, 45, e 65 dias. No experimento 2 (novembro de 2007 a fevereiro de 2008), foram utilizados 60 sacos de náilon, 30 deles com 10 g de folhas de E. azurea, e os demais contendo a mesma quantidade de folhas de S. auriculata. Após 30 minutos, 2, 4, 8, 12, 24, 36, 48, 60 e 72 dias os sacos foram retirados do lago. Em ambos os experimentos, após serem retirados do lago, os sacos foram levados ao laboratório, e o material remanescente fixado em formol 4%, lavado e triado, os organismos encontrados foram identificados e conservados em álcool 70%. No experimento 1, o maior coeficiente de decomposição (K) foi observado no primeiro período (K= 0,023 d-1 ) em relação ao segundo (K= 0,018 d-1 Palavras–Chave: Chironomidae, Lago dos Manacás, macrófitas, Naididae, relação carbono:nitrogênio ), no entanto, não houve diferença significativa. Observou-se o aumento da densidade e riqueza dos Oligochaeta ao longo do estudo em ambos os períodos. Naididae foi a família dominante, estes organismos por possuírem a capacidade de se locomover na coluna d'água próximo ao substrato, mostraram-se melhores colonizadores do que Enchytraeidae e Tubificidae. No experimento 2, ao final dos 72 dias, observou-se menor biomassa total de E. azurea (2,65 g MS) em relação à S. auriculata (5,10 g MS), sendo que na primeira macrófita registrou-se a diminuição da relação carbono: nitrogênio durante o estudo, enquanto que em S. auriculata não foi observada a diminuição desta razão. Chironomidae e Naididae foram as famílias com maiores densidades, representando mais de 95% da fauna em ambas as macrófitas. Os coletores foram o grupo funcional mais abundante em E. azurea e S. auriculata, confirmando a predominância destes organismos nas folhas em decomposição na região tropical. / The present study was composed of two experiments. The first with the objective to verify the colonization of Oligochaeta during decomposition of the macrophyte Eichhornia azurea (Sw.) Kunth, while the second experiment analized the faunistic struture of the macroinvertebrates along decomposition of E. azurea and Salvinia auriculata Aubl. Experiment 1 was divided into two periods (1st period: September to November 2007; 2nd period: February to April 2008). In each period, 21 nylon bags containing 10 g of dry leaves of E. azurea, were placed in the lake, and removed at intervals of 2, 5,8, 12, 25, 45, and 65 days. In experiment 2 (November 2007 to February 2008), 60 nylon bags were used, 30 of them filled with 10 g of dry leaves of E. azurea and the others, containing the same amount of dry leaves of S. auriculata. After intervals of 30 minutes, 2, 4, 8, 12, 24, 36, 48, 60 and 72 days the bags were taken out of the lake. In both experiments, after out of the lake, the bags were taken to the laboratory, and the remanescent material was fixed in a formol solution 4%, washed and sorted. The organisms were identified and preserved in 70% alcohol. In experiment 1, the highest decomposition coefficient (K) was observed in the first period (K= 0.023 d-1) in relation to the second (K= 0.018 d-1 ), however with no significant difference. An increase of density and richness of Oligochaeta along the study was observed in both periods. Naididae was the most dominant family, represented by the genera Allonais, Chaetogaster, Dero and Pristina. These organisms, for their ability of moving themselves in the water column, near the substrate, showed to be better colonizers than Enchytraeidae and Tubificidae. In experiment 2, at the end of the 72 days, it was observed a small fraction of total biomass of E. azurea (2.65 g DM) in relation to S. auriculata (5.10 g DM), whereas in the first macrophyte it was registered a decrease of the carbon: nitrogen relationship during the study, while in S. auriculata it was not observed the decrease of this rate. Chironomidae and Naididae were the families with the higher densities, representing more than 95% of the fauna in both macrophytes. The collectors were the most abundant functional group in E. azurea and S. auriculata, attesting to the predominance of these organisms in the leaves in decomposition in the tropical region.

Recent studies have shown that permafrost soils in the northern circumpolar region store almost twice as much carbon as the atmosphere. Since soil organic carbon (SOC) pools have large regional and landscape-level variability, detailed SOC inventories from across the northern permafrost region are needed to assess potential remobilization of SOC with permafrost degradation and to quantify the permafrost carbon-climate feedback on global warming. This thesis provides high-resolution data on SOC storage in five study areas located in undersampled regions of the continuous permafrost zone (Zackenberg in NE Greenland; Shalaurovo and Cherskiy in NE Siberia; Ary-Mas and Logata in Taymyr Peninsula). The emphasis throughout the five different study areas is put on SOC partitioning within the landscape and soil horizon levels as well as on soil forming processes under periglacial conditions. Our results indicate large differences in mean SOC 0–100 cm storage among study areas, ranging from 4.8 to 30.0 kg C m-2, highlighting the need to consider numerous factors as topography, geomorphology, land cover, soil texture, soil moisture, etc. in the assessment of landscape-level and regional SOC stock estimates. In the high arctic mountainous area of Zackenberg, the mean SOC storage is low due to the high proportion of bare grounds. The geomorphology based upscaling resulted in a c. 40% lower estimate compared to a land cover based upscaling (4.8 vs 8.3 kg C m-2, respectively). A landform approach provides a better tool for identifying hotspots of SOC burial in the landscape, which in this area corresponds to alluvial fan deposits in the foothills of the mountains. SOC burial by cryoturbation was much more limited and largely restricted to soils in the lower central valley. In the lowland permafrost study areas of Russia the mean SOC 0–100 cm storage ranged from 14.8 to 30.0 kg C m-2. Cryoturbation is the main burial process of SOC, storing on average c. 30% of the total landscape SOC 0–100 cm in deeper C-enriched pockets in all study areas. In Taymyr Peninsula, the mean SOC storage between the Ary-Mas and Logata study areas differed by c. 40% (14.8 vs 20.8 kg C m-2, respectively). We ascribe this mainly to the finer soil texture in the latter study area. Grain size analyses show that cryoturbation is most prominent in silt loam soils with high coarse silt to very fine sand fractions. However, in profiles and samples not affected by C-enrichment, C concentrations and densities were higher in silt loam soils with higher clay to medium silt fractions. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 4: Manuscript.</p>

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv. / Härtill 4 uppsatser.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv., 2007. / Härtill 4 uppsatser.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniversitet, 2006. / Härtill 4 uppsatser.