Navegando por Assunto "Carbono"

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Acesso aberto (Open Access)
Carbon and oxygen isotope geochemistry of Ediacaran outer platform carbonates, Paraguay Belt, central Brazil
(2007-09) RICCOMINI, Claudio; NOGUEIRA, Afonso César Rodrigues; SIAL, Alcides Nóbrega
After the late Cryogenian glaciation the central region of Brazil was the site of extensive deposition of platformal carbonates of the Araras Group. This group includes a basal cap carbonate sequence succeeded by transgressive, deep platform deposits of bituminous lime mudstone and shale. Facies and stratigraphic data combined with carbon and oxygen isotopic analyses of the most complete section of the transgressive deposits, exposed in the Guia syncline, were used to evaluate the depositional paleoenvironment and to test the correlation of these deposits along the belt and with other units worldwide. The studied succession consists of 150 m thick tabular beds of black to grey lime mudstone and shale with predominantly negative d13CPDB values around –2.5 to -1 . The d13CPDB profile of Guia syncline shows a clear correlation with the upper portion of Guia Formation in the Cáceres region, about 200 km to the southwest. The d13CPDB profile of the Araras Group is comparable with d13CPDB profiles of Ediacaran units of the southern Paraguay Belt, western Canada, and the Congo and Kalahari cratons. Moreover, facies distribution, stratigraphy and the carbon isotopic profile of the Araras Group match the middle Tsumeb Subgroup in Namibia, which reinforces the Ediacaran age assigned to the Araras Group.
Acesso aberto (Open Access)
Carbon content in Amazonian Oxisols after forest conversion to pasture
(2009-12) SILVA JÚNIOR, Mário Lopes da; DESJARDINS, Thierry; SARRAZIN, Max; MELO, Vânia Silva de; MARTINS, Paulo Fernando da Silva; SANTOS, Elaine Rodrigues; CARVALHO, Claudio Jose Reis de
Soil plays an important role in the C cycle, and substitution of tropical forest by cultivated land affects C dynamic and stock. This study was developed in an area of expansion of human settlement in the Eastern Amazon, in Itupiranga, State of Pará, to evaluate the effects of native forest conversion to Brachiaria brizantha pasture on C contents of a dystrophic Oxisol. Soil samples were collected in areas of native forest (NF), of 8 to 10 year old secondary forest (SF), 1 to 2 year old SF (P1–2), 5 to 7 year old SF (P5–7), and of 10 to 12 year old SF (P10–12), and from under pastures, in the layers 0–2, 2–5 and 5–10 cm, to evaluate C levels and stocks and carry out separation of OM based on particle size. After deforestation, soil density increased to a depth of 5 cm, with greater increase in older pastures. Variation in C levels was greatest in the top soil layer; C contents increased with increasing pasture age. In the layers 2–5 and 5–10 cm, C content proved to be stable for the types of plant cover evaluated. Highest C concentrations were found in the silt fraction; however, C contents were highest in the clay fraction, independent of the plant cover. An increase in C associated with the sand fraction in the form of little decomposed organic residues was observed in pastures, confirming greater sensitivity of this fraction to change in soil use.
Acesso aberto (Open Access)
Efluxo de CO2 do solo em sistemas de produção de palma de óleo na Amazônia Oriental
(Universidade Federal do Pará, 2017-02-21) COSTA, Alessa Nayhara Mendanha; VASCONCELOS, Steel Silva; http://lattes.cnpq.br/0719395243841543
Tropical forest areas play an important role in the global carbon cycle. However, anthropogenic disturbances have altered the structure of the ecosystem and consequently imply in the carbon budget. To evaluate how changes in land use influence the efflux of CO2 from the soil (the main pathway of CO2 displacement in soil to atmosphere), it is possible to understand how the different types of vegetation affect the CO2 efflux of the soil, evaluating the variables that contribute to this process. A greater understanding of this influence motivates the study in different ecosystems, which seek to identify and develop practices that increase carbon stock and nutrient cycling, such as agroforestry systems (SAFs). Due to the expressive expansion of the oil palm in the Amazon region, the objective of this research was to evaluate the effects of CO2 efflux from the soil, as well as its control variables, in two oil palm production systems (conventional palm oil production systems and agroforestry systems with oil palm). The research was developed in the municipality of Tomé-Açu in areas of family farming and production. Soil CO2 efflux, soil temperature and soil gravimetric moisture were evaluated between March 2016 and November 2016. The stocks of fine roots and litter in the systems were evaluated in the period of higher precipitation (May) and lower precipitation (October). Soil CO2 efflux was higher in successional forest areas, intermediate in oil palm agroforestry systems, and lower in conventional palm oil systems. The CO2 efflux of the soil is sensitive to the "conversion" of forest areas into oil palm crops. The "soil metabolism" in the more diversified oil palm (SAF) system is more similar to that of the more ecologically integrated system (secondary forest).
Acesso aberto (Open Access)
Estimativas de biomassa e carbono em áreas de vegetação secundária no território paraense
(Universidade Federal do Pará, 2018-06-29) OLIVEIRA JUNIOR, Luis Augusto Lima; KELLER, Michael Maier; http://lattes.cnpq.br/1869582564376606; ADAMI, Marcos; http://lattes.cnpq.br/7484071887086439; https://orcid.org/0000-0003-4247-4477
Land use dynamics is a very intense process in the Amazon landscape because forest areas are constantly targets of deforestation, often illegal, which compromises the environmental balance of this ecosystem. In this context, a widespread element in the region's landscape is secondary vegetation (SV). The SV appears after a disturbance and can evolve and reach the characteristics close to a primary forest. This work aims to generate above-ground biomass and carbon estimates for the SV areas in the State of Pará for 2014. The methodology uses the variable GSDY (Growing-Season Degree-Years), calculated by SV age (TerraClass), temperature, and precipitation. The variable GSDY is part of a model proposed by Johnson et al. (2000) and Zarin et al. (2001), which generates above-ground biomass and carbon estimates. VS was classified into five classes according to its age. More than 6.9 million hectares of VS were mapped in the State of Para, representing more than two billion tons (t) of biomass (one million t of carbon) contained in VS. More than 2.8 million hectares of VS were vulnerable in 2014 because of SEMAS – PA Normative Instruction that enables cleaning these areas five years old or less (except those protected by law), with no environmental authorization needed. The SV loss could represent a considerable carbon emission to the atmosphere and massive damage to this region's balance.
Acesso aberto (Open Access)
Estoque de biomassa e carbono florestal em unidades de paisagem na Amazônia: uma análise a partir da abordagem metodológica ecologia da paisagem
(Universidade Federal do Pará, 2013-03-22) PEREIRA, Izaura Cristina Nunes; GAMA, João Ricardo Vasconcellos; http://lattes.cnpq.br/9058536716453750; PEZZUTI, Juarez Carlos Brito; http://lattes.cnpq.br/3852277891994862
The present work aims to demonstrate the central variability in forest in relation to stocks and forest carbon biomass above ground, from the identification and characterization based on remote sensing, landscape units in an area located in the municipality of Belterra, western Pará State, from the theoretical-conceptual approach of landscape ecology. For the scope of this proposition, the methodology used was based on the literature review on the topic, data acquisition and orbital mapping, use of remote sensing techniques, field data collection, processing and statistical analysis. The work is divided into four chapters, followed by general considerations of the work. Based on the theoretical-methodological of Landscape Ecology, analyzes the social and environmental dynamics of the municipality of Belterra, who currently experiences the expansion of agricultural activities, especially agriculture mechanized soy. From the analysis of multi-temporal Landsat images of the city we could assess the distribution of existing forest cover in the same as well as the spatial distribution of the main landscape units identified. Considering this clipping was held to collect field data via forest inventory in four forest types (forest high plateau, low plateau forest, secondary vegetation and ecological tension) to obtain morphometric parameters of vegetation and subsequent quantification of stocks biomass and carbon contained in each unit as well as observe the structural behavior of the same forest. The adoption of the landscape as the spatial scale of analysis proved to be quite satisfactory in the quantification of biomass and carbon stocks of forest to allow considering the influence of socioeconomic dynamics in reducing these stocks. Furthermore, analyzes showed that recognition of the heterogeneity of forest cover is an essential element for obtaining carbon estimates according to the structural characteristics of vegetation which varies with the topography of the terrain, with the species present and the geographical features, which involves the type climate, geomorphologic characteristics, soil and geological area.
Acesso aberto (Open Access)
Estoque e ciclagem de carbono de sistemas agroflorestais em Tomé-Açu, Amazônia Oriental
(Universidade Federal do Pará, 2010) BRANCHER, Tobias; VASCONCELOS, Steel Silva; http://lattes.cnpq.br/0719395243841543
Agroforestry systems (SAFs) constitute an important agricultural practice of land use directed at food production and environmental services. The objective of this study was to evaluate carbon stock and cycling of 4 agroforestry systems (SAF) with different age and species composition, and a secondary vegetation (“capoeira”), in Tomé-Acu, northeast of Pará State, Eastern Amazon. Carbon stocks in soil, litter and aboveground biomass were measured. Carbon flux associated with litterfall and aboveground biomass increment was measured over a year between 2008 and 2009. The SAFs were divided into four categories, called SAF 1, SAF 2, SAF 3 and SAF 4, being (SAF 1: cacau, açaí, bananeira e seringueira, 14 years old, SAF 2: cacau, açaí, bananeira, seringueira, taperebá, paricá e macacaúba, 14 years old, SAF 3: cupuaçu, açaí, teca e mogno, 9 years old, SAF 4:cupuaçu, açaí e paricá, 9 anos years old). In each system we set four plots, where soil and plant samples were collected, including diameter at breast height (DAP) and height (h), which were used to estimate the aboveground biomass. Within plots were installed collectors to measure the deposition of litterfall and sampled soil and litter used to estimate carbon stocks. There was no significant difference between SAFs in relation to soil carbon stock. The SAF 3 was significantly lower than the other SAF in relation to aboveground carbon and SAF 4 had the highest annual litterfall deposition among all treatments. The SAF did not differ in relation to soil and litter carbon stocks. Net primary production reached 2.54, 6.11, 9.54 and 16.27 Mg C ha-1 yr-1 in SAF 1, 2, 3 and 4, respectively. The age of the SAFs had no significant effect on the amount of carbon accumulated during one year.
Acesso aberto (Open Access)
Estoques de carbono em sistemas agroflorestais de cacaueiro como subsídios a políticas de serviços ambientais
(Universidade Federal do Pará, 2012-02-22) PEREIRA NETO, João Augusto; SANTANA, Antônio Cordeiro de; http://lattes.cnpq.br/2532279040491194; PONTE, Marcos Ximenes; http://lattes.cnpq.br/0120823127408114
Cocoa Agroflorestry Systems (AFS) of the BR-230 road in addition to being an alternative to the recovery of deforested and degraded areas of the Amazon are able to integrate forest and agriculture providing environmental services such as the maintenance of biodiversity, the water cycle and the carbon stocks. However, the economic logic of market of cocoa does not take into consideration the market failures, especially not internalize the positive externalities of environmental services, mainly cocoa Agroforestry systems carbon of the BR-230 road. Therefore, the farmer is not compensated for this effort in maintaining the environmental service carbon in your activity. Thus, in this paper we present a compensation mechanism with a methodology for the REDD to productive activities from the study of the Marginal Private Cost and Marginal Private Benefit of the cocoa market in the Satate of Pará, using parameters of the productive activity of cocoa AFSs of the BR-230 road, as the Carbon stocked in time to compose the Socioenvironmental Benefit. This Socioenvironmental Benefit is composed by the Productivity of the activity, the value of Carbon Stocked and primarily by the Carbon Stocked in time of cocoa AFSs for a period of thirty years. As a result of the study we have the the Socioenvironmental Benefit tool to solve the problems of market failure for the deployment of REDD to the farmers of AFS, this compensation mechanism is based on a Positive Socioenvironmental Externality policy justified by Pigouviana Tax. Therefore, the compensation mechanism presents a vision of integration between the social, economic and environmental dimensions as different logic to farmers of AFSs of transamazonian highway that promotes benefits for conservation and preservation without deforestation and without degradation to which the farmer to keep perpetuating the conservation allowing an increase in income of farmers in the period where there is greater activity cost and no revenue return and in the last years as a form of investment for a renewal of the area in use with a new planting or maintenance of an old area or new area deployment of AFS. Thus, this compensation mechanism is an important factor in the financing of a new development model of Amazon with a REDD policy.
Acesso aberto (Open Access)
Estoques de carbono resultantes de mudanças de uso e cobertura do solo e sua relação com os indicadores socioeconômicos nos municípios de Paragominas e Ulianópolis, Pará
(Universidade Federal do Pará, 2016-02-29) SOUSA, Larissa Melo de; LIMA, Aline Maria Meiguins de; http://lattes.cnpq.br/6572852379381594; ADAMI, Marcos; http://lattes.cnpq.br/7484071887086439
The land use land cover change are pointed out by several studies to cause environmental damage, such as carbon dioxide (CO2) into the atmosphere The objective of this study is to relate the socio-economic indicators and carbon emissions with the different land use land cover change in the municipalities of Paragominas and Ulianópolis for the years 2004, 2008, 2010 and 2012. For this, they were certain areas according to each class of use and land cover and the mean of the stock of Above Ground Biomass (AGB) for each of the classes of use and land cover provided by TerraClass Project for 2004. Subsequently were quantified CO2 emissions associated with land use land cover change cover. In addition, the socioeconomic data were related to estimates of carbon. The results indicate that much of the forest area was converted to the classes of agriculture and pasture. The total carbon stored above ground, between the period 2004 to 2012 ranged from 163 x106 Mg C to 161 x106 Mg C Mg C in Paragominas and de 31 x106 Mg C to 29 x106 Mg C in Ulianópolis. The net CO2 emissions between the period 2004 to 2012 amounted to 5.8x106 Mg CO2 to Paragominas and 7.4 x106 Mg CO2 to Ulianópolis. In Ulianópolis it was observed a moderete linear relationship between socioeconomic indicators and carbon stocks, while in Paragominas, there was no linear correlation. The conclusion is that the dynamics of use and land cover classes are based on agriculture and livestock as variables in the economic matrix of the municipalities. The carbon stock in the municipalities has decreased due to reduction of forest areas and the advancement of areas of annual agriculture and clean pasture, so the study area is negatively contributing to the removal of CO2 from the atmosphere. Land use land cover change has positive effects on the socio-economic indicators, but increase carbon emissions.
Acesso aberto (Open Access)
Influence of the sodium content on the reactivity of carbon anodes
(2008-09) BATISTA, Jefferson dos Santos; SILVEIRA, Benedito Inácio da
Spent anodes, denominated butts in the aluminum industry, are recycled as part of the raw material used to produce new anodes. The fragmentation of the butt generates some sodium-rich powder, which is captured and included in the recycled material. This paper evaluates the influence of sodium content on anode reactivity. Six formulations with 0 to 25% butt powder were used. An average increase of 48 ppm of sodium from one to another formulation caused average increments of 3.38 and 2.72% for air and CO2 reactivity, respectively. The quality-related figures varied from 1.34 to 1.12 for CO2 and from 1.10 to 0.62 for air, showing quality loss in higher sodium content and higher impact on air reactivity. The Fischer formula predicted a carbon specific consumption of - 48.47 kg.t-1 Al for baked carbon anodes with 127 ppm to 367 ppm of sodium content, showing that the sodium can cause relevant carbon losses and increase costs of the aluminum production.
Acesso aberto (Open Access)
Mudanças de uso da terra em paisagens agrícolas com palma de óleo (Elaeis guineensis Jacq.) e implicações para a biodiversidade arbórea na Amazônia Oriental
(Universidade Federal do Pará, 2015-09-30) ALMEIDA, Arlete Silva de; VIEIRA, Ima Célia Guimarães; http://lattes.cnpq.br/3761418169454490
The expansion of oil palm in the Amazon is associated with a number of public policy, in the form of actions and programs and has provoked economic and ecological changes in the region and challenge the society to monitor and control the palm cultivation expansion on a large scale. The municipalities from the "Palm region" in Pará state, as Moju, intensified cultivation of this palm tree and suffered intense modifications in thier natural ecosystems. In Addition this new frontier of bioenergy challenged the paradigm of sustainability, with social and environmental conflicts and replacement of subsistence farming by the palm. Little is known about the consequences that a large-scale monoculture can cause in the amazonian environment. To follow this new productive dynamic with palm oil are required interdisciplinary studies that contribute to identify how environmental respond to changes associated to the new agricultural frontier with oil palm. In this context, the overall objective of this research is to analyze the changes, the conflicts and the trajectories of land uses, as well as the value of conservation of the biodiversity of the plantations of oil palm and other land uses predominate in eastern Pará. The work is organized into five chapters including the first one which introduce the subject of the thesis. The other four are guided by the following specificobjectives: a) analyze the land use conflicts in Moju county, Pará state, Brazil, within areas of permanent preservation -PPA, according with the Brazilian Forest Code of 2012; b) map and quantify the types of land cover and land use in 2013 in three areas (Ubá, Arauaí e Mamorana), where the implementation of oil palm cultivation is present; c) capture the space-time variability in the changes of trajectories in landscapes of 1991-2013 and identify the effect of changes of land use in the structure of the landscape; and d) investigate the variation in the carbon stock and species richness of trees in different land use and vegetation cover in the three studied areas. For the study of conflicts in APPs in Moju, were used 29 multispectral images of high resolutions by RapidEye satellite of 2010. The results show that the area destined legally for permanent preservation (APP) in Moju is 47,357.06 ha, representing 5.21% of the municipal area. The PPAs with natural vegetation represent 68.60% of the APPs of the municipal area, about 28% of the PPAs have use conflicting with predominance of pasture in 15.6%. Only 0.63% of APPs is occpupied by palm oil. The application of the new recomposition guidelines for APPs according to the new Forest Code will result in the loss of 60.69% of the APP-recovered areas in this municipality. The analysis of vegetation cover and land use in 2013 in the three selected areas (Ubá, Arauaí and Mamorana) was made by the method of decision tree in images of the satellite Landsat-8 year of 2013. The overall performance of the classification was 0.87% (index kappa). The results show greater extension of primary forests in Mamorana, area in the beginning of cultivating oil palm. Agriculture predominate in all areas analysed. For the analyses of trajectories changes of land uses and the effects on the landscape structure i the landscape we made classification using decision tree method in images of the satellite Landsat TM-5 for the years 1991, 1995, 2001, 2005 and 2010, and Landsat-8 for the year 2013, through the ImgToos programs, ENVI and ArcGIS. The landscape structure was carried out through the landscape metrics (PLAND, LPI, PD and PROX-MN) using the FRAGSTATS program. v. 3.3. The classification achieved overall performance of 0.87% for the kappa index. In the period 1991-2013 the conversion of primary forest to other uses occurred in a ratio of 47.82%, while the degraded forest (17%) and oil palm (11%) had the largest increase in occupancy in 2013. We emphasize that the transition of the primary forest to palm oil was 20% in the 22 years under study, which led to a PD (fragments density index) with considerable amounts, attaining a level from 0.3 to 4.5 (number of patches/ 100 ha). Such conversions define the fragmentation intensity of primary forest. The investigation about the biodiversity response and carbon stocks in different forest cover and land uses was made through a floristic inventory of trees greater than or equal to 2 cm DBH in plots ranging from 1, 500 and 2500 m2 on each forest cover/land use analyzed. Intheall 8.55 ha sampling were registered 5,770 individual trees, distributed in 425 species and 74 families. The primary forest presented carbon stock higher than 80 Mg/ha, while palm oil, pasture and secondary forest presented less than 50 Mg/ha, noting that the oil palm retains impoverished communities of trees, and its tree composition is poorer than the pasture, while the stock of carbon is higher. In this study, in 22 years of the analysis we observed that primary forests covers less than 30% of the landscape, a critical level for biodiversity conservation.
Acesso aberto (Open Access)
Transporte eletrônico em um alótropo de grafeno nanofitas de bifenileno com bordas hidrogenadas
(Universidade Federal do Pará, 2024-11-06) SOUZA, Lucas Pessoa de; DEL NERO, Jordan; http://lattes.cnpq.br/5168545718455899
Carbon-based nanostructured materials have aroused considerable interest in the scientific community due to their remarkable technological properties. Among the various carbon structures, graphene stands out as an allotropic form with a two-dimensional (2D) hexagonal structure, resulting from the sp² hybridization of carbon. In this work, we investigated the electronic properties of structures based on a 2D allotropic form of carbon, composed of rings of 4, 6 and 8, called Biphenylene. The research used the hydrogenation of the top of Biphenylene nanosheets, with the aim of exploring applications in molecular electronics. To achieve this, we employ Density Functional Theory (DFT) to optimize the structures and combine DFT with the Non-Equilibrium Green Functions method to obtain electronic transport properties. The band structure results indicate that, among the unit cells analyzed, the Biphenylene cell behaves as a conductive material when analyzed in the zigzag direction, while in the archmair direction they present characteristics of semiconductors. Regarding electronic transport properties, the Biphenylene nanodevice demonstrates behaviors like those of a field effect transistor in the studied range. Specifically, the zzBFNRH-O device, which exhibits field-effect transistor characteristics in the range of 0.00 V to 0.07 V, the same behavior we can observe for the zzBFNRH-H device, which exhibits the behavior of a field effect transistor for ranges from 0.00V to 0.50V. We can observe the behavior of the archBFNRH-O device where it indicates the behavior of a metal, presenting current conduction values after 0.10V. The archBFNRH-H device presents the behavior of a semiconductor, which indicates a gap of 1.8eV. We can observe that when the device width increases, this gap decreases. These results demonstrate that structures based on Biphenylene present themselves as a promising alternative for the development of nanodevices and applications in molecular electronics.
Acesso aberto (Open Access)
Transporte pneumático fluidizado: estudos de casos aplicados à indústria do alumínio primário
(Universidade Federal do Pará, 2011-08) VASCONCELOS, Paulo Douglas Santos; MESQUITA, André Luiz Amarante; http://lattes.cnpq.br/1331279630816662
This work is a contribution to science and applied technology developed to fluidized bed and fluidized motion conveying used in the powder handling of the industrial processes. In the case of fluidized bed it is proposed an empirical equation to predict the minimum fluidization velocity for the fluoride alumina, crust powder and others powders used in the industrial processes with good results compared with the experiments and the equations available in the literature. It was also studied the constitutive equations to predict the behavior of the angle of repose and interparticles friction as a function of the superficial velocity of fluidization. In a second step it is proposed an equation to predict the capacity of the Air Pneumatic Fluidized Conveyor with good results compared with the experiments for fluoride alumina. The Air Fluidized Conveyor is a contribution to applied technology reducing the consumption of energy, it operates even in upward direction, and so, decreasing the rate kWh/ton in the powder handling of the industrial processes.
Acesso aberto (Open Access)
Variação sazonal do carbono e um ecossistema de manguezal na Amazônia Oriental: florística, clima e economia
(Universidade Federal do Pará, 2019-02-25) RODRÍGUEZ, Nelson Antonio Castellón; JARDIM, Mário Augusto Gonçalves; http://lattes.cnpq.br/9596100367613471; VITORINO, Maria Isabel; http://lattes.cnpq.br/4813399912998401
This interdisciplinary research aims at investigating the seasonal and economic dimensions of the mangrove forest, in relation to the capture, storage and carbon emissions, from spatial variation of floristic, physical-chemical, biological and climatic variables for the period of 2016 and 2017 in the Eastern Amazon. The study area is located at the Experimental Site of UFRA / UFPA in the village of Cuiarana, Salinópolis-PA. The floristic inventory method consisted of transects and plots, with DBH measures ≥ 2.5cm, monthly precipitation data generated by the CMORPH technique and the tide of the Salinopólis Fundeadouro. The stock of organic carbon, CO2 emissions and physico-chemical and biological variables were measured through seasonal sampling in nine 20x20m plots in three mangrove strata. Socioeconomic data are based on the combination of carbon dioxide fluxes measured by a micrometereological tower installed in the study area and interviews with residents of Cuiarana Village. Spatially, the main results show that for the three mangrove strata the dominance of Rhizophora mangle (L) was observed, with the highest values of phytosociological indices. The species Avicennia germinans (L.) Stearn presented a higher positive correlation (0.72) with organic carbon during the rainy season. The largest stocks and emissions of organic carbon in the soil occurred in the adult mangrove in the rainy season when compared to the young / dwarf and intermediate strata. In the socioeconomic context, the villagers identified nine mangrove properties of which the main ones are the consumption and the sale of the crab in the less rainy season. However, services for carbon capture and storage in the soil presented higher income in the rainy season. The incomes estimated by mangrove goods and services were R $ 92,660.50 per hectare per year.