Submitted by Irene Nascimento (irene.kessia@ufpe.br) on 2017-04-10T17:20:12Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) DISSERTAÇÃO -DAVI CAVALCANTI certa.pdf: 1682949 bytes, checksum: e88ff7ec323c0df6eb4f0102509ba5b3 (MD5) / Made available in DSpace on 2017-04-10T17:20:12Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) DISSERTAÇÃO -DAVI CAVALCANTI certa.pdf: 1682949 bytes, checksum: e88ff7ec323c0df6eb4f0102509ba5b3 (MD5) Previous issue date: 2016-02-23 / Capes / O crescimento da população mundial vem causando um aumento substancial na demanda por energia o que poderá causar em curto prazo uma crise energética, pois grande parte da energia consumida em todo mundo é proveniente de fontes não renováveis como o petróleo, já que sua prospecção e utilização tem causado grandes danos a natureza, impactando vários ecossistemas e colaborando com o aquecimento global. Por estes motivos, novas tecnologias para geração de energia limpa vêm sendo criadas. Um exemplo destas são as células a combustível, que são dispositivos que convertem energia química em elétrica. Porém esta tecnologia apresenta algumas limitações, como deficiências na transferência de elétrons, baixa geração de potência e altos custos associados a utilização de catalizadores metálicos, os quais aumentam os custos de implantação e dificultam sua utilização em larga escala. Visando superar estas limitações uma variação desta tecnologia foi desenvolvida, a chamada célula a combustível fotossintética. Neste tipo de célula a combustível, microalgas como a Chlorella vulgaris são utilizadas no compartimento catódico substituindo catalizadores químicos melhorando sua sustentabilidade e reduzindo os custos de implantação. As utilizações de cátodos de microalgas também colaboram com o sequestro de carbono da atmosfera, o convertendo em oxigênio e biomassa rica em metabolitos de grande valor comercial como amido e lipídios. No presente estudo a microalga C. vulgaris foi utilizada no compartimento catódico de uma célula a combustível fotossintética a fim de se analisar sua eficiência na produção de energia, sua capacidade de sequestrar o dióxido de carbono da atmosfera e seu acúmulo de materiais de reserva como amido e lipídios totais. Na primeira parte deste estudo a microalga C. vulgaris foi utilizada como aceptora de elétrons em um compartimento catódico, onde durante 10 dias de experimento foram avaliados a quantidade de CO2 capturada pelas células de algas (7mg/L de CO2), a composição da biomassa, Amido (3%) e Lipídios (70%) e parâmetros eletroquímicos como a Eficiência Coulômbica (CE = 33,1%) e densidade de corrente máxima (Idmax = 147 mA cm²). Em seguida esta condição foi submetida a um planejamento fatorial completo 2², onde as variáveis independentes, tempo de iluminação e a concentração de nitrogênio foram testadas sobre a produção de eletricidade e acúmulo de amido e lipídios. Durante os experimentos foi constatado que a iluminação é o fator que mais influi na geração de energia, onde foram obtidos valores de densidade de corrente máxima Idmax = 178 mA/cm² com uma eficiência coulômbica de 42,5%, além de uma acumulação máxima de amido de 38% e 77% de lipídios, demonstrando que a utilização de um cátodo fotossintético para produção de energia é viável e eficiente na produção de metabólitos com elevado valor comercial. / The global population growth has caused a substantial increase in demand for energy, which in short-term may cause an energy crisis, since much of the energy consumed throughout the world comes from non-renewable sources like oil. Besides its exploration and use cause great damage to the environment, affecting diverse ecosystems and contributing to global warming. For those reasons, are being created new technologies for clean energy generation. An example of these technologies is Fuel Cells, which are devices that convert chemical energy into electric. However, this technology has some limitations, such as defects in electron transfer, low power output and high costs associated with the use of metal catalysts, which increase deployment costs and hamper its use on a large scale. Aiming to overcome these limitations, a variation of this technology was developed, the so-called photosynthetic fuel cell. In this type of fuel cell, microalgae such as Chlorella vulgaris are used in the cathode compartment replacing chemical catalysts improving their sustainability and reducing deployment costs. The uses of microalgae cathodes also collaborate with carbon capture from the atmosphere, turning it into oxygen and biomass rich in metabolites of great commercial value as starch and lipids. In the current study the microalgae C. vulgaris was used in the cathode compartment of a photosynthetic fuel cell in order to analyze its energy production efficiency, their ability to sequester atmospheric carbon dioxide and its accumulation of reserve materials such as starch and total lipids. The first part of this study microalga C. vulgaris was utilized as an electron acceptor in a cathode compartment, which were analyzed during 10 days of experiment the amount of CO2 captured by the algae cells (7mg/L-1 of CO2), the composition of the biomass starch (3%) and lipids (70%) and electrochemical parameter as coulombic efficiency (CE = 33.1%) and the maximum current density (mA Idmax = 147 cm²). Then this condition was subjected to a complete factorial design 2² where the independent variables, illumination time and the concentration of nitrogen were tested on the production of electricity and accumulation of starch and lipids. During the experiments it was evidenced that enlightenment is the factor that most affects the power generation, which were obtained maximum current density values Idmax = 178 mA/cm² with a coulombic efficiency of 42.5%, and a maximum accumulation of 38% of starch and 77% of lipid, demonstrating that the use of a photosynthetic cathode for energy generation is feasible, and also in the production of metabolites with a high commercial value.

Objetivando estudar o seqüestro de carbono em sistemas de restauração florestal e discutir suas potencialidades e entraves perante MDL florestal, este trabalho teve dois objetivos principais: i) quantificar taxas iniciais de seqüestro de carbono nos compartimentos aéreo, radicular, solo e serapilheira, de plantios de restauração da Mata Atlântica, com 20 espécies (10 pioneiras, 10 não pioneiras), submetidos a manejos contrastantes (usual e intensivo), instalados sobre pastagem de Brachiaria no espaçamento de 3 m x 2 m; e ii) comparar os estoques de carbono destes sistemas, ao final do sexto ano, com valores determinados em fragmento de floresta madura vizinho ao ensaio. Ambos localizados em Anhembi/SP (Estação Experimental de Anhembi/USP e Mata do Barreiro Rico). O tratamento usual consistiu em adubação de base e capina mecânica na linha de plantio até dois anos, e, o intensivo teve adubações complementares e capina química em área total até dois anos. Foram desenvolvidos modelos alométricos de estimativa da biomassa através de amostragem destrutiva de 80 árvores, sendo quatro indivíduos por espécie, selecionados por classes de área seccional. Determinaram-se massa seca e teor de C, para os compartimentos copa, lenho e raízes. Através das equações, do inventário ao sexto ano e dos teores de carbono, foram calculados os estoques de carbono por compartimento, nos dois tratamentos. Determinaram-se os estoques de carbono na biomassa herbácea, serapilheira e solo. Foi calculada a variação de carbono por compartimento nos dois tratamentos. Os estoques de carbono na floresta madura foram quantificados utilizando dados de 10 parcelas de inventário, aplicados em modelo alométrico adequado para Mata Atlântica. A densidade da madeira variou até 3 vezes entre espécies (0,22 a 0,70 gcm-3), o teor de C foi pouco variável (46,5%). Foram adequadamente ajustadas equações de biomassa lenhosa, raiz e copa com base na área seccional, altura e densidade da madeira. A porcentagem de raízes é expressiva (30%) na biomassa total, mas as espécies não pioneiras mostraram maior razão raiz:parte aérea (0,32) que as pioneiras (0,28). A silvicultura intensiva elevou o crescimento do compartimento lenhoso em 250% (1,85 para 6,45Mg ha-1ano-1), devido a maior eficiência da copa e alocação de C no tronco. O carbono no solo embora representativo, não propiciou seqüestro em 6 anos, dada alta variabilidade espacial. O tratamento intensivo obteve maior seqüestro de C, atingindo 4,22Mg C ha-1 ano-1 (64% no tronco e galhos, e 20% nas raízes). Os estoques de C no solo e serapilheira foram próximos entre o sistema intensivo de restauração e floresta madura, sendo os estoques no tronco, galhos e raízes, o diferencial entre os sistemas. Com base no crescimento médio das árvores e estoque de C nas restaurações até sexto ano (7 e 21kg árvore-1 e 5,2 e 18,2Mg C ha-1, respectivamente no sistema usual e intensivo), e no tamanho médio das árvores e estoque de C na floresta madura (204kg árvore-1 e 138Mg C ha-1) estimou-se cerca de 50 anos para o sistema intensivo atingir maturidade, embora haja necessidade de estudos relacionados à biodiversidade e sustentabilidade destes sistemas de restauração a longo prazo. / In order to study carbon sequestration in forest restoration systems and discuss its potential and barriers to the CDM forestry, this paper had two main objectives: i) quantify the initial rate of carbon sequestration in compartments aboveground, roots, soil and forest floor, on Atlantic forest restoration, with 20 native species (10 pioneers and 10 non pioneer), submitted to contrasting management conditions (usual and intensive), installed on Brachiaria decumbens pasture in 3 x 2 m spacing, and ii) comparing the carbon stocks of these two systems, observing the end of the sixth year of restoration, with values determined in a fragment of mature forest adjacent to the test. Both studies are located in Anhembi, São Paulo (USP Anhembi Experimental Station and the Barreiro Rico reserve). The usual treatment consisted of only fertilizer at planting and mechanical weeding only in the row up to two years, while the intensive treatment had additional fertilization beyond crop fertilization and chemical weed control also in the entire area until two years after planting. We developed allometric equations for estimating biomass through destructive sampling of 80 trees. Four individuals per species were selected based on classes of sectional area. Dry weight were determined and the carbon content for wood and roots. Through the equations, and carbon content we calculated carbon stocks per compartment, in both treatments. Carbon stocks in herbaceous, in the litter and soil were also determined. With these estimates we calculated the variation of carbon per compartment in the two restoration systems. Carbon stocks in mature forest were quantified using data from 10 permanent plots of inventory and applying appropriate allometric models. The wood density varied between species by up to 3 times (0.22 to 0.70 g cm-3) while the C content was relatively constant (46.5%). Appropriately adjusted equations for aboveground woody biomass, root and crown biomass were established using cross-sectional area, height and wood density. The percentage of roots is significant (30%) compared to the total, and non-pioneer species showed a higher ratio root / shoot (0.32) than the pioneer (0.28). The intensive forestry increased growth of woody compartment by 250% (1.85 to 6.45 Mg ha-1 yr-1), given the greater efficiency of the canopy and allocation of C to the trunk. The carbon content in the soil although representative in the total stock, did not result in C sequestration in the six years period, given its high spatial variability. The largest C sequestration was observed in the intensive treatment, reaching 4.22 Mg C ha-1 yr-1, 64% on the trunk and branches, and 20% in roots. The values of C stock in soil and litter were similar between the intensive system of forest restoration and mature forest, and indeed the trunk, branches and roots stocks, the major difference between the systems. Based on the average growth of trees and carbon stocks in the restoration and the first 6 years (7 and 21 kg tree-1 in the usual system and intensive, and 5.2 and 18.2 Mg C ha-1 in these same treatments), and the average tree size and carbon stocks in mature forest (204 kg tree-1 and 138 Mg C ha-1), a 50 years period was estimated for the intensive system to reach forest maturity although there is a need for studies relating biodiversity and sustainability of these restored systems in the long run.

Le taux de matière organique (MO) d'un sol influence ses propriétés physico-chimiques et son activité biologique. La dynamique de cette MO, particulaire ou dissoute, influence également la concentration de CO2 atmosphérique et joue ainsi un rôle sur les changements climatiques. Une des réponses à la diminution du stock de carbone dans les sols est l'apport de matière organique exogène. Le carbone organique dissous, intervenant dans les principaux mécanismes de préservation et/ou dégradation de la matière organique du sol (MOS), n'est cependant que peu pris en compte lors de l'étude de ces apports exogènes. Le principal objectif de cette étude est de mieux caractériser les MOD présentes dans les horizons de surface d'un sol. Les eaux collectées par bougies poreuses sur quatre profondeurs (15 à 100 cm) proviennent de parcelles amendées en 2006 (150 t/ha de compost de déchets verts et bio-déchets) et de parcelles témoins sous prairie. Les eaux ont été caractérisées par l'intermédiaire des techniques analytiques globales et moléculaires (spectrofluorimétrie, chromatographie d'exclusion de taille, thermochimiolyse, CG/SM). Les résultats de cette étude ont mis en évidence pour les deux types de parcelles une variabilité de la MOD (taille et polarité) suivant la profondeur et la saison. Le suivi de la MOS/MOD, et plus particulièrement des composés lipidiques, a permis de confirmer la séquestration du carbone organique exogène. La caractérisation de la MOD s'avère ainsi être un indicateur de la qualité des sols. / Organic matter (OM) content influences soil physical and chemical properties and its microbial activity. OM, particulate or dissolved, plays a key role on climate changes. Exogenous organic matter amendments are used to tackle the various problems associated with the decrease in soil carbon content. Dissolved Organic Carbon (DOC), involved in main mechanisms of preservation and / or degradation of organic matter is however only scarcely taken into account in the study of such amendments. The main objective of this study was to better characterize the DOM present in the surface horizons of a soil. The percolating waters collected from 2006 amended plots (150 t/ha of green waste and bio-waste compost) and reference plots are characterized by global and molecular techniques (fluorescence spectroscopy, size exclusion chromatography, themochemolysis, GC/MS). Size and polarity of DOM molecules change depending on seasons and depths. These analyses reveal exogenous organic carbon sequestration. DOM study is thus part of the quality soil indexes.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This study aims to quantify and analyze the distribution of the stock of above-ground biomass in Deciduous Forest fragments (FED) in the Region of the Northwest RS, generating the necessary information to support the development of forestry projects. Thus, we installed seven sampling unit of 12 x 12 m with subunits of 5 x 5 m and 1 x 1 m to quantify the natural regeneration classified as Stratum 1 (E1), 2 (E2) and 3 (E3), the E1 is composed of plants with less than 1.3 m from the ground, the E2 all vegetation with over 1.3 m in height and less than 5 cm diameter at breast height (DBH) and E3 all vegetation with DBH between 5 and 10 cm. In the main units all vegetation with more than 10 cm DBH were classified as stratum 4 (E4). For quantification of biomass above ground, after the overthrow of the trees, all tree vegetation was weighed directly in the field, with split trunk (wood with bark), thick branches (diameter greater than 5 cm), thin branches (diameter less than 5 cm), and miscellaneous sheets, these being identified at the species level. To estimate the biomass of the allometric models adjustments were collected the following information dendrometric E4 diameters at 0 (baseline), DAP, 25, 50, 75 and 100% of morphological inversion point height (HPIM) of height HPIM, total height. To estimate the above-ground biomass of different specific gravity methods (MEB) was obtained from wood and other literature were calculated from the disks taken at the time of the DAP, these disk, shelled, had approximately 2 cm thick. The results indicated that the average stock of biomass for the FED was 371.1 Mg.ha-1. The trees with the breast height diameter (DBH) greater 10 cm accounted for over 89% of the biomass (4759 kg). To build the allometric models, the equations adjusted without stratification, have adjusted coefficient of determination (R2aj.) Between 0.726 to 0.972 and standard error of estimate in percentage (Sxy%) ranging from 33.5 to 119.6, the best adjusted model, for not stratified data set was obtained by the stepwise procedure, represented by the following equation: PST = β0 + β1.(DAP3) + β2.H + β3.(DAP3.H), with R2aj.. 0.972 and Sxy 33.5%. For the stratified, only diameter class above 15 cm of acceptable parameters, R2aj. 0.968 and Sxy 26.8%. For the estimation of biomass by different methods, the direct method has accumulated 11,450 kg bole biomass (PSF) for the seven installments. The indirect method that is closer to the PSF was the biomass obtained from the volume of the equation and the MEB arithmetic average of 13,141 kg, and the one with the biggest difference was obtained by rigorous and volume weighted average MEB, which totaled 20,060 kg, and arithmetic mean MEB differed from the PSF by Dunnett's test at 5% probability. It is recommended reliable quantification of above-ground biomass in stratum E4, especially the larger ones, as they may provide greater error in the quantification and estimation of forest biomass. / Este estudo teve por objetivo quantificar e analisar a distribuição do estoque de biomassa acima do solo em fragmentos de Floresta Estacional Decidual (FED) na Região Noroeste do Estado do RS, gerando as informações necessárias para subsidiar a elaboração de projetos florestais. Para tanto, foram instaladas sete unidade amostrais de 12 x 12 m com subunidades de 5 x 5 m e 1 x 1 m para quantificação da regeneração natural classificada em Estrato 1 (E1), 2 (E2) e 3 (E3), o E1 é composto das plantas com menos de 1,3 m de altura do solo, o E2 toda vegetação com mais de 1,3 m de altura e menos que 5 cm de diâmetro a altura do peito (DAP) e o E3 toda vegetação com DAP entre 5 e 10 cm. Nas unidades principais toda vegetação com mais de 10 cm de DAP ficaram classificadas com estrato 4 (E4). Para a quantificação da biomassa acima do solo, após a derrubada das árvores, toda a vegetação arbórea foi pesada diretamente em campo, sendo fraccionadas em tronco (madeira com casca), galhos grossos (diâmetro maior que 5 cm), galhos finos (diâmetro menor que 5 cm), folhas e miscelâneas, estas sendo identificadas a nível de espécies. Para as estimativas de biomassa por ajustes de modelos alométricos foram coletadas as seguintes informação dendrométricas do E4, os diâmetros à 0 (base), DAP, 25, 50, 75 e 100% da altura do ponto de inversão morfológico (HPIM), altura do HPIM, altura total. Para a estimativa da biomassa acima do solo por diferentes métodos a massa específica básica (MEB) da madeira foi obtida na literatura e outras foram calculadas a partir dos discos tirados na altura do DAP, estes disco, sem casca, apresentavam aproximadamente 2 cm de espessura. Os resultados indicaram que o estoque médio de biomassa para a FED foi de 371,1 Mg.ha-1. As árvores com o diâmetro altura do peito (DAP) maior 10 cm representaram mais de 89% da biomassa (4759 Kg). Para o ajuste de modelos alométricos, as equações ajustadas, sem estratificação, apresentam coeficiente de determinação ajustado (R2aj.) entre 0,726 à 0,972 e erro padrão da estimativa em porcentagem (Sxy%) variando de 33,5 a 119,6, o melhor modelo ajustado, para o conjunto de dados não estratificado, foi obtido através do procedimento de Stepwise, sendo representado pela seguinte equação: PST = β0 + β1.(DAP3) + β2.H + β3.(DAP3.H), com R2aj. de 0,972 e Sxy% de 33,5. Para a forma estratificada, apenas a classe de diâmetro acima de 15 cm apresentou parâmetros aceitáveis, com R2aj. de 0,968 e Sxy% de 26,8. Para a estimativa da biomassa por diferentes métodos, o método direto acumulou 11.450 Kg de biomassa do fuste (PSF) para as sete parcelas. O método indireto que mais se aproximou do PSF foi a biomassa obtida através do volume da equação e da MEB média aritmética, 13.141 Kg, e o que apresentou a maior diferença foi obtida pelo volume rigoroso e MEB média ponderada, que totalizou 20.060 Kg, e MEB média aritmética diferiram estatisticamente do PSF pelo teste de Dunnett em nível de 5% de probabilidade de erro. Recomenda-se quantificação fidedigna da biomassa acima do solo no estrato E4, principalmente os maiores indivíduos, pois estes podem propiciar maior erro na quantificação e estimativa da biomassa florestal.

Conselho Nacional de Desenvolvimento Científico e Tecnológico / Soil carbon (C) sequestration in agriculture soil is a low cost option to mitigate global climatic change. No-till (NT) associated with good husbandry practices could compensate up to 15% of the anthropogenic CO2 emissions by storing the C from atmosphere as soil organic carbon (SOC). To be fully accepted as a mitigation alternative, research must be conducted to improve the accuracy of soil C sequestration estimates on field experiments as well as those made by mathematical models at regional and local scales. Complementarily, is necessary to improve the knowledge about the SOC stabilization mechanisms, delimiting the real soil´s capacity into accumulate C, quantifying how much of the stored C could be re-emitted to the atmosphere by changes in soil management. The present work is divided in four chapters with the objective to answer these questions. The first chapter has the objective to discuss the importance of sampling depth (0-0.30, 0-0.60, and 0-0.90 m) and the definition of a reliable and adequate baseline for the calculation of the C sequestration rates. Two long-term field experiments from a temperate (Mollisol) and a sub-tropical (Oxisol) climate soil were selected for this research. The experiments tested soil tillage systems (conventional tillage (CT) and NT) (Mollisol and Oxisol) and sources and rates of nitrogen amendment on corn in the Mollisol (control without N, 168 kg N ha-1 as ammonium sulfate, and 168 kg N ha-1 as organic fertilizer) and different crop rotation systems in the Oxisol (R0:soybean-wheat, R1:soybean-wheat-soybean-oat, and R2:soybean-oat-soybean-oat+vetch-corn-radish-wheat). The increase of sampling depth provided limited contribution to the estimates of C sequestration rates due to the increase of the error on SOC stocks estimates at deeper soil depths. To improve the C sequestration rate estimates, SOC temporal dynamic analysis should be preferred rather than the comparison of the SOC stocks of paired plots at a unique time point. The second chapter had the objective to apply simple mathematical equations to describe the SOC dynamics and improve the estimates of C sequestration rates and also to understand the role of the macroaggregate formation on SOC accumulation and saturation. The use of linear and kinetic (exponential growth) equation was adequate to describe the SOC dynamics increasing the accuracy of the C sequestration rate estimates by reducing errors promoted by soil spatial variability. The SOC accumulation was a function of the amount of C input to the soil and the macroaggregate formation to protect SOC. The SOC saturation process occurred from the smaller to the larger aggregate size fraction, limiting the capacity of a given superficial soil layer to accumulate SOC. However, the SOC saturation at superficial soil layers did not indicate the end of C sequestration in the soil, since the SOC accumulation occurred at sub-superficial soil layers. In the third chapter, the mathematical approach to determine changes on SOC stocks and the SOC saturation-induced limitation for C sequestration were applied to improve the accuracy of the Hénin e Dupuís (1945) one- 8 compartmental mathematical model into predict future soil C sequestration rates. The long-term field experiment from the Mollisol was selected for this research because of the better data availability (sampling years) and also by the presence of two treatments under CT and NT with SOC saturated soil layers. The mathematical adjustment (by linear equations) of the SOC dynamic coefficients improved the adjustment of the model‟s predictions. The SOC saturation-induced restriction for SOC accumulation on the mathematical model avoided the overestimation of the soil‟s potential for C sequestration. The predictions of the mathematical models indicate that the Mollisol‟s superficial layer (0-0.05 m) under NT could maintain significant C sequestration rates for up to 50 years as a function of the amount of C input to the soil. For the fourth chapter, a detailed study of the SOC pools in water-stable aggregate size fractions by granulometric and densimetric fractionation was carried out. The objective was to identify the pools where SOC accumulation was occurring and what SOC stabilization mechanisms were present. This will provide estimates of the NT potential to promote long-term C sequestration. SOC accumulation occurred preferentially in the more stable and recalcitrant SOC fractions (Mollisol and Oxisol) or in microaggregate and macroaggregate physically protected fractions (Mollisol). In the Oxisol, the SOC enrichment occurred mostly in the mineral associated-SOC fractions extra-microaggregates occluded within meso- and macroaggregates, while in the Mollisol, the SOC accumulation occurred in both intra- and extra-microaggregate mineral associated-SOC fractions. More than 78 and 92% of the C sequestration verified in the Mollisol and Oxisol, respectively, were considered as long-term by occurring in stable SOC fractions. / O seqüestro de carbono (C) em solos agrícolas é uma opção de baixo custo para mitigação das mudanças climáticas globais. O plantio direto (PD), associado a boas práticas agronômicas, pode compensar até 15% das emissões antrópicas de CO2 ao armazenar o C drenado da atmosfera na forma de carbono orgânico (CO) do solo. Para ser amplamente aceito como alternativa de mitigação, pesquisas devem ser conduzidas a fim de melhorar a precisão das estimativas de taxas de seqüestro de C em experimentos de campo, assim como as previsões feitas por modelos matemáticos em escalas regionais e locais. Complementarmente, é necessário aprimorar o conhecimento sobre os mecanismos de estabilização do CO, delimitando a capacidade real do solo em acumular C e quantificando quanto do C acumulado no solo pode ser re-emitido para atmosfera por mudança no manejo do solo. Desta maneira, o presente trabalho se divide em quatro capítulos com o objetivo de abordar estas questões. O primeiro capítulo tem por objetivo discutir a importância da profundidade de amostragem (0-0,30; 0-0,60; 0-0,90 m) e da definição de situações de linhas-base confiáveis a adequadas para o cálculo das taxas de seqüestro de C. Para isto, foram utilizados dois experimentos de longa duração sobre um solo de clima temperado (Mollisol) e outro de clima sub-tropical (Oxisol). Os experimentos testaram efeitos de sistema de preparo do solo (preparo convencional (PC) e PD) (Mollisol e Oxisol) e fontes e doses de nitrogênio para o milho no Mollisol (testemunha (T), 168 kg N ha-1 na forma de sulfato de amônia (AM) e 168 kg N ha-1 na forma de adubo orgânico (AO)) e diferentes sistemas de rotação de culturas no Oxisol (R0:soja-trigo, R1:soja-trigo-soja-aveia e R2:soja-aveia-soja-aveia+ervilhaca-milho-nabo-trigo). O aumento da profundidade de amostragem não contribuiu com a melhoria das estimativas de taxas de seqüestro de C devido ao aumento do erro nas estimativas dos estoques de CO nas camadas mais profundas de solo. Para melhoria das estimativas das taxas de seqüestro de C devem-se preferir análises temporais da dinâmica do CO no solo ao invés da comparação de estoques de CO em um único momento. O segundo capítulo tem por objetivo aplicar equações matemáticas simples para descrever a dinâmica do CO e melhorar as estimativas taxas de seqüestro de C e também entender o papel da formação de macroagregados no acúmulo e saturação de CO no solo. O uso de equações lineares e cinéticas (crescimento exponencial) foi adequado para descrever a dinâmica do CO, aumentando a precisão das estimativas de taxas de seqüestro de C ao reduzir os erros de estimativa por variabilidade espacial do solo. O acúmulo de CO no solo mostrou-se uma função da quantidade de C aportada ao solo por resíduos vegetais e a formação de macroagregados no solo para proteção do CO. O processo de saturação do solo ocorreu das menores para as maiores frações de agregados do solo, limitando a capacidade de uma 6 determinada camada de solo em acumular CO. No entanto, verificou-se que a saturação de camadas superficiais de solo não indica o fim do seqüestro de C neste solo, visto que o acúmulo de CO passa a ocorrer em camadas sub-superficiais. No terceiro capítulo, a aproximação matemática para determinar mudanças nos estoques de CO e a limitação na capacidade do solo em acumular CO promovida pelo processo de saturação dos agregados do solo foram aplicados para melhorar a precisão do modelo matemático uni-compartimental de Hénin e Dupuís (1945) em prever futuras taxas de seqüestro de C. O Mollisol foi escolhido para este estudo em função da maior disponibilidade de dados (anos de amostragem) e também pela presença de dois tratamentos em PC e PD com camada de solo saturada por CO. O ajuste matemático (por equações lineares) dos coeficientes da dinâmica do CO melhorou o ajuste das previsões do modelo com os dados observados. A restrição do modelo matemático quanto à capacidade do solo em acumular CO (saturação de CO) evitou a superestimação do potencial de seqüestro de C deste solo. As previsões do modelo matemático indicam que a camada superficial (0-0,05 m) do solo sob PD pode apresentar taxas significativas de seqüestro de C por até 50 anos, em função da quantidade de C adicionada ao solo. No quarto capítulo, foi realizado um estudo detalhado dos compartimentos do CO em função da sua distribuição em classes de tamanhos de agregados estáveis em água e o fracionamento granulométrico e densimétrico do CO. O objetivo foi identificar em quais compartimentos está ocorrendo o acúmulo de CO no solo, os mecanismos de estabilização do CO, estimando o potencial do PD em promover sequestro de C de longa duração. Verificou-se que o acúmulo de C ocorre preferencialmente em frações mais estáveis e recalcitrantes do CO (Mollisol e Oxisol) ou em frações protegidas fisicamente por micro e macroagregados (Mollisol). No Oxisol, o enriquecimento de CO ocorre principalmente nas frações de CO associadas aos minerais extra-microaggregados oclusas em meso e macroagregados de solo, enquanto que no Mollisol, o acumulo de CO ocorre tanto na fração intra como extra microagregados. Mais de 78 e 92% do seqüestro de C verificado no Mollisol e Oxisol, repectivamente, foi considerado de longa duração por ocorrer em frações estáveis do CO.

Orientador: Juliano Carlos Calonego / Resumo: A calagem é uma pratica agrícola indispensável para a correção da acidez em solos tropicais contribuindo para o aumento da produção de grãos e biomassa. A aplicação superficial de calcário e gesso em sistema de semeadura direta (SSD) tem sido uma estratégia usada para melhorar as propriedades químicas do solo em subsuperficie, todavia, existem poucas informações sobre os efeitos dessa prática no balanço de carbono no sistema solo-planta-atmosfera. Dessa forma, o trabalho teve como objetivo avaliar a emissão acumulada anual de C-CO2, o estoque de C e N no solo, a qualidade da matéria orgânica do solo (MOS) e a atividade biológica, bem como a deposição de C e N pela biomassa do sistema radicular e pelos resíduos produzidos no final do ciclo das culturas na superfície do solo, em função da aplicação superficial de calcário e gesso em um SSD de longa duração. O experimento foi instalado em 2002 em um delineamento experimental em blocos casualizados no esquema de parcelas subdivididas e 4 repetições. A aplicação de calcário e gesso ocorreu nos anos de 2002, 2004, 2010 e por último em 2016 quando foi dado início a condução do presente trabalho. As parcelas foram constituídas por quatro níveis de calcário (ausência de aplicação, 3260, 6520 e 13040 kg ha-1) e as subparcelas por dois níveis de gesso agrícola (ausência de aplicação e 10000 kg ha-1). Ao final dos dois anos agrícolas a aplicação de calcário promoveu um aporte médio de 2,70 Mg ha-1 de C e 150 kg ha-1 de N pelo sistema rad... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Liming is an indispensable agricultural practice for the correction of acidity in tropical soils contributing to the increase in the production of grains and biomass. The superficial application of lime and gypsum in a direct seeding system (NT) has been a strategy used to improve the chemical properties of the soil in subsurface, however, there is little information about the effects of this practice on the carbon balance in the soil-plant-atmosphere system. Thus, the work aimed to evaluate the accumulated annual emission of C-CO2, the stock of C and N in the soil, the quality of soil organic matter (SOM) and the biological activity, as well as the deposition of C and N by the biomass of the root system and by the residues produced at the end of the crop cycle on the soil surface, due to the superficial application of lime and gypsum in a long-term NT. The experiment was installed in 2002 in a randomized block design in a split plot and 4 replications scheme. The application of lime and gypsum occurred in the years 2002, 2004, 2010 and lastly in 2016 when the conduction of the present work began. The plots consisted of four levels of lime (no application, 3260, 6520 and 13040 kg ha-1) and the subplots by two levels of agricultural gypsum (no application and 10,000 kg ha-1). At the end of the two agricultural years, the application of lime promoted an average supply of 2.70 Mg ha-1 of C and 150 kg ha-1 of N by the root system of the soybean, corn and U. ruziziensis in relatio... (Complete abstract click electronic access below) / Doutor

In Peru, nearly 32 million people rely heavily on human-made coastal irrigation agricultural hubs that rely on water from melting glaciers, snowpack, and rain transported by rivers and canals from high in the Andes. However, Peru’s water resources are in a vulnerable state as climate change has shifted rainfall patterns causing glacier retreat affecting nearly the loss of one-third of the glaciers. In recent decades, an increase and expansion of irrigation projects in Peru require agriculture practices to consider environmental impacts directly. Now is the time to explore the sustainability of the desert agroecosystems and understand how different water management practices influence the supporting soil’s health so decision-makers can plan for future change in water resources and any feedbacks to the productivity of the soils. Over the past 40 years, Peru has led some of the largest scale water management projects on earth to convert infertile coastal desert soils into irrigated agricultural land. Still, these efforts can come at a severe local cost with impacts to groundwater quality, salination of the soil, toxic concentrations of trace metals due to evaporation, and overuse of fertilizer and pesticides. This thesis presents a study to assess how drip irrigation impacts desert soil chemistry within one of Peru’s desert irrigation projects in Arequipa’s southern district. We explored a chronosequence of drip irrigation in vineyards of 9-, 16- and 35- years. Results showed that both soil carbon and salinity accumulated progressively over time but that spatial accumulation patterns were influenced by proximity to the irrigation drip line. By 35 years, salinity levels exceeded what would be tolerances for most crops. Trace metals, such as Mn, Zn, and Ni, increased with time under drip irrigation and have significant relationships with Fe, present in the highest concentrations, seemingly controlling the patterns due to co-precipitation. However, no trace metals were found in quantities that would exceed Peru’s limits for agricultural soils. While drip irrigation is considered a water conservation strategy and widely promoted in the region over other irrigation techniques like high water volume furrow irrigation, its use may accelerate localized negative impacts to surface soil health. These progressive changes highlight the need for effective monitoring and salinity mitigation strategies in the region. This project is part of the bilateral technical program between Purdue University and Universidad Nacional San Agustín (UNSA) called the Arequipa Nexus Institute for Food, Water, Energy, and the Environment.

<div>In fire-prone forests, tree taxa and burn temperature are the major controllers of the chemical and physical properties of pyrogenic organic matter (PyOM), the aromatic carbon-rich product of the incomplete combustion of plant biomass, that accumulates in soil in such settings. These controls also dictate how soil microbes can degrade plant C once it enters into soil as previous studies demonstrate that increased fire temperature results in low PyOM degradability but also impacts the decomposition of the original soil. However, we know little about how taxa and temperature of C-inputs impact the production and accumulation of cellular residues from soil microbes, which can be the dominant source of stabilized soil organic matter in many ecosystems. </div><div>This work presents the results of the analysis of soil microbial amino sugars, as proxies for soil microbial necromass, from long-term soil incubation experiments, 180 and 600 days, that were amended with jack pine (JP) and red maple (RM) wood or their PyOM produced at 300°C or 450°C. Both wood taxa amendments resulted in an increase in microbial sugar residues compared to non-amended soils but RM, the taxa with the highest proportion of soluble sugars and low tannin content, exhibited the highest percentage increase. Soils amended with PyOM exhibited lower amino sugar content as compared to their wood but no difference compared to controls (non-amended soils). There was no difference in soil amino sugars observed between the PyOM derived from the two taxa nor between the temperature of pyrolysis, possibly due to only small amounts of bioavailable C and N in the PyOM. Total amino sugar concentrations varied significantly between PyOM and fresh wood treatments, with PyOM treatments yielding 659 – 730 μg/ g soil while wood treatments yielded 757 – 930 μg/ g soil early in incubations. While fungal-derived amino sugars were dominated in all treatments, longer soil incubation time, 600 days vs 180 days, resulted in a proportionately greater decrease bacterial-derived amino sugars. Overall, at 180 days, PyOM treatments exhibited 19-27% of soil N and 4-5% of soil C quantifiable as amino sugars while wood treatments exhibited 27-28% of total soil N and 6-7% of total soil C as amino sugars. This work shows, for the first time, that on a per C or per N basis, PyOM versus fresh wood addition to soils will result in a net depletion of microbial residues. The variable response in amino sugars between treatments and incubation time highlights the importance and dynamic nature of the physicochemical characteristics of organic matter input to soil in controlling the contribution of soil microbial residues to that soil. </div><div><br></div>

Carbon offsets have been developed as one tool to incentivise investments by developed nations in climate change mitigation activities in developing countries. The carbon offsets can be used towards the countries’ own mitigation targets but are also meant to benefit developing countries by providing a pathway to clean development. Photovoltaic water pumping (PVWP) technology is a solution to use PV for irrigation, which can be used to restore degraded grasslands and help farmers adapt to climate change. Restoration of degraded grasslands increases the production of grass and will therefore increase the amount of carbon in the soil, a process that may mitigate climate change. However, poor farmers often have limited access to irrigation technology and this thesis assesses how carbon offsets may bring revenues to increase adaption of PVWP technology in remote areas of the Chinese grasslands. PV modules can be used to mitigate climate change in different ways; the most common is to produce electricity to replace fossil fuel power capacity. The novelty of this thesis is that it assesses the alternative mitigation possibilities for the PVWP project proposed here. Further, consideration of water constraints that limit the applicability of the technology and a framework to assess the trade-offs between potential downstream water impacts and environmental co-benefits of the project add to the novelty of this thesis. Policy barriers for the project will also be considered.  Used to restore severely degraded grasslands, PVWP projects show high carbon sequestration potential and successfully compete with grid electricity as carbon offset projects. A case is analysed and it shows that the carbon market could play a role in increasing the feasibility of PVWP projects. However, water issues make project implementation very site-specific and some indicators to determine feasibility is proposed to be blue water availability, evaporation recycling ratio and water productivity. Water use must also be looked at with respect to climate, food and energy security, calling for a nexus approach to evaluate the project suitability. In May 2016, grassland management projects are excluded from the Clean Development Mechanism to the Kyoto Protocol, and this limits project implementation to the voluntary markets. / Avhandlingen är ämnad att läsas av beslutsfattare inom klimatområdet samt aktörer på de olika klimatkompensationsmarknaderna. Klimatkompensation har utvecklats som ett verktyg för att stimulera industriländers investeringar i klimatprojekt i utvecklingsländer. Klimatkompensation kan användas för att nå industriländernas egna klimatmål men är också tänkta att gynna utvecklingsländer genom att tillhandahålla en ”ren” utvecklingsmöjlighet. Solcellsdrivna vattenpumpar (eng. photovoltaic water pumping: PVWP) är en teknik för att använda solceller för bevattning. Tekniken kan användas för att restaurera degraderade gräsmarker och för att hjälpa jordbrukare anpassa sig till klimatförändringarna. Restaurering av gräsmarker ökar produktionen av gräs vilket medför ökad mängden kol i marken, en process som kan mildra klimatförändringarna. Men fattiga bönder har ofta begränsad tillgång till bevattningsteknik och denna avhandling utvärderar hur klimatkompensation kan ge intäkter för att öka användningen av PVWP i avlägsna delar på den kinesiska slätten. Solceller kan användas för att mildra klimatförändringarna på olika sätt och vanligast är att producera el för att ersätta fossila bränslen. Det är därför viktigt att titta på alternativkostnaden för PVWP-projekten som föreslås här. Vidare begränsar vattentillgången projekten och ett ramverk för att tydliggöra avvägningar mellan vattenrelaterade problem och miljömässiga fördelarna med ett projekt är nödvändigt. Klimatpolitiska styrmedel sätter också upp vissa begränsningar för projekten. Om PVWP används för att återställa mycket degraderade gräsmarker, visar projekten hög klimatnytta och de kan framgångsrikt konkurrera med solel till nätet som klimatkompensationsprojekt. En fallstudie visar att klimatkompensationsmarknaden skulle kunna spela en viss roll för att öka antalet PVWP-projekt. Däremot gör vattenfrågan projektens geografiska plats viktig och indikatorer för att avgöra genomförbarheten föreslås vara ”blåvattentillgång”, ”förångningsåtervinning” och ”vattenproduktivitet”. Vattenanvändningen måste också ses i förhållande till klimat, mat- och energisäkerhet, vilket kräver en nexusstrategi för att utvärdera projekten. I skrivande stund (maj 2016) är projekt rörande skötsel av gräsmarker exkluderade från mekanismen för ren utveckling (CDM) till Kyotoprotokollet och detta begränsar projekten till de frivilliga klimat-kompensationsmarknaderna. / <p>QC 20160711</p> / Demonstration and Scale-Up of Photovoltaic Solar Water Pumping for the Conservation of Grassland and Farmland in China

Research on soil organic carbon (SOC) within the northern Great Plains has not been clearly documented. Objectives of this study were (i) to inventory literature reporting SOC responses to agroecosystem management, (ii) extract data for the Northern Great Plains Rapid Carbon Assessment, and (iii) summarize data to identify relationships between SOC and land use management. Soil organic carbon at 0 ? 15 cm depth was 1.57 ? 6.87 kg C m-2, 1.56 ? 5.34 kg C m-2, and 1.48 ? 5.48 kg C m-2 under grasslands, conservation tillage (CST), and conventional tillage (CT), respectively. Soils with a Productivity Index (PI) of 80 ? 100 had greater mean SOC (4.14 kg C m-2) across all managements. Correlation between SOC and PI for CT was significant (r=0.240) (P=0.05) and highly significant (r=0.418) (P=0.01) for CST. Management practices for cropland soils combined with productivity potential appear to relate to the C accrual potential of northern Great Plains soils.