Artigos Científicos - IG

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Frações de fósforo e simbiose micorrízica em floresta secundária em resposta a disponibilidade de água e nutrientes na Amazônia oriental
(Instituto Nacional de Pesquisas da Amazônia, 2015-09) MAIA, Rodrigo da Silva; VASCONCELOS, Steel Silva; CARVALHO, Claúdio José Reis de
The availability of soil nutrients (especially phosphorus) and soil water strongly influence mycorrhizal symbiosis in forest ecosystems. The aim of this study was to evaluate the impact of litter removal and increased soil moisture availability on the spore density and mycorrhizal colonization of apogeotropic and non-apogeotropic roots of a secondary forest stand in eastern Amazonia. We determined the percentage of mycorrhizal colonization of apogeotropic and non-apogeotropic (0-10 cm soil depth) fine roots (diameter ≤ 2 mm), spore density, glomalin concentration, and soil phosphorus availability. Litter removal did not reduce soil phosphorus availability. The spore density was not affected by litter removal. In general, the variables varied on a seasonal basis, except the mycorrizal colonization of non-apogetropic roots and glomalin concentration, but were not affected by irrigation. Mechanical damage to the apogeotropic root system, inherent to the fortnightly litter removal, may have contributed to decrease mycorrhizal colonization of both apogeotropic and non-apogeotropic roots and, consequently, soil glomalin. Our results suggest that the reduction of soil cover may have negative impact over the fungus-plant symbiosis.
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A categorização e a validação das respostas abertas em surveys políticos
(Universidade Federal do Pará, 2017-10) HENKEL, Karl
The article deals with the problem of the categorization of answers about politics, government, and democracy obtained through open-ended questions in a survey with a random sample of 800 interviewees. In order to identify the degree of comprehensibility of the questions, a pre-test and missing value analysis were carried out to elaborate a psychometric profile. In the categorization process, the deductive method was superior to the inductive one. The media and the life cycle position influences perception about politics and government. The validation of intra- and inter-coder reliability shows that coders, at a given moment, begin to accept irrational responses as rational ones, and that they can be subject to framing effects.
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O papel da grande mineração e sua interação com a dinâmica urbana em uma região de fronteira na Amazônia
(Universidade Federal de Minas Gerais, 2016) MELO, Ana Carolina Campos de; CARDOSO, Ana Cláudia Duarte
This article deals with particularities of the urbanization process associated to the mining dynamics, which articulate directly the extraction territories to the global accumulation circuits. On the Amazon frontier, the forms of capital operationalization, altered the urban structuring, the urban-rural relationship and caused an enormous impact on the nature and on the most vulnerable sections of the population. The analysis is based on the Lefebvrian derivation of extended urbanization and on the notion of levels of social reality; has the objective of exploring the relational connections of the urban with the global and local levels and allow the construction of parallels between the iron ore extraction at the Serra dos Carajás and the gold exploration, at the Vale do Husco, northern region Chile. We observe an urban dynamic governed by the global sphere, and parallel processes, embryos of a new urban matrix, in the local sphere, centered on the reproduction of life and the construction of citizenship.
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Gestão da informação em saneamento básico no Estado do Pará sob o enfoque do ciclo informacional
(Brasileira da Associação Interamericana de Engenharia Sanitária e Ambiental, 2017-12) CONDURÚ, Marise Teles; PEREIRA, José Almir Rodrigues
This paper employs information management to analyze the sanitation information cycle in the State of Pará, due to the need of implementing municipal information systems. Methodologically, the research used Lancaster’s Information Transfer Cycle approach. Questionnaires were applied to collect and qualitative analysis of data from state agencies of the Basic Sanitation sector. Among the results, there was a lack of state and municipal information systems in addition to a deficient informational framework in the state, portrayed by a lack of systematic record, integration and sharing, as well as availability of produced information. It was concluded that there is a need to implement a local information system as an instrument of the sanitation state policy, targeting the informational knowledge related to the sector besides a larger participation of Pará municipalities in the national information system. It was also proposed the restructuring of informational dimension in the State of Pará, through a new sanitation information cycle.
Acesso aberto (Open Access)
Geology and petrology of the Salto do Céu Suite: tectonic and stratigraphic implications on the SW Amazonian Craton
(Sociedade Brasileira de Geologia, 2018-09) MACAMBIRA, Moacir José Buenano; SOUSA, Maria Zélia Aguiar de; RUIZ, Amarildo Salina; BATATA, Maria Elisa Fróes; PIEROSAN, Ronaldo
The basic rocks of the Salto do Céu Suite outcrop as sills and flows in the southwestern Amazon Craton, Rondonian-San Ignacio Province, with an age of about 1.44 Ga. Sills are 2 to 30 m thick being hosted by pelites of the Aguapei Group. The flows are up to 5 m thick and cover this unit. Typical textures of magma mingling are observed near the contact with granites of Rio Branco Suite. The Rio Branco Intrusive Suite is composed of basic and acid rocks, as well as hybrid rocks that indicate mixing processes between basic and acids magmas. U-Pb (TIMS zircon) results indicate ages around 1.4 Ga for both terms. The Salto do Céu Suite rocks have tholeiites affinity classified as subalkaline and iron-rich tholeiitic basalts, with mg# values between 0.30 and 0.51. They can be separated into two groups, based on La N ; one is richer in ETR with La N greater than 100, while the other one has La N less than 100. Rocks of the Salto do Céu Suite and Rio Branco Suite are interpreted as a bimodal suites showing magma mingling features such as those developed in continental intraplate settings, extensional regime associated to the Columbia/Nuna breakup.
Acesso aberto (Open Access)
Mineral chemistry and crystallization parameters of the A-type Paleoproterozoic Bannach Granite, Carajás Province, Pará, Brazil
(Sociedade Brasileira de Geologia, 2018-09) MESQUITA, Caio José Soares; ALMEIDA, José de Arimatéia Costa de; DALL'AGNOL, Roberto
The A-type Paleoproterozoic Bannach Granite belongs to the Jamon Suíte and cross-cut the Archean units of the Rio Maria Domain in the Carajás Province. It comprises eight facies with varied mafic content and texture: even-grained cumulate granite (CG), even coarse-grained biotite-amphibole monzogranite (cBAMz), even coarse-grained amphibole-biotite monzogranite (cABMz), porphyritic biotite monzogranite (pBMz), even coarse-grained leucomonzogranite (cLMz), early even medium-grained leucomonzogranite (EmLMz), late even medium-grained leucomonzogranite (LmLMz) and even fine-grained leucomonzogranite (fLMz). In the less evolved facies, the dominant amphibole is Fe-hornblende passing to Fe-edenite or hastingsite, with associated cummingtonite/grunerite originated from the destabilization of clinopyroxene. Biotite has ferroan composition and approaches annite in the late-emplaced leucomonzogranite. Plagioclase varies from andesine to oligoclase or from oligoclase to albite. Titanite, magnetite, and ilmenite are found in all granite facies showing magmatic origin. The near liquidus temperatures vary between 943ºC and 795ºC and the estimated emplacement pressure is 300 ± 50 MPa (~11.1 ± 1.9 km). Amphibole Fe/(Fe + Mg) ratios together with magmatic magnetite and titanite indicate that these granites crystallized at moderately oxidizing conditions, similar to those admitted for the Jamon granite and magnetite series granites of Laurentia. However, the composition of biotite suggests a more reduced character close to NNO to NNO -0.5. The late leucomonzogranite facies is an exception because it displays high Fe/(Fe + Mg) ratios in biotite and approaches to the reduced granites of Carajás, Laurentia and Fennoscandia in this regard. It derived from a more reduced source than the other facies of Bannach Granite
Acesso aberto (Open Access)
Rhyacian evolution of the eastern são luís craton: petrography, geochemistry and geochronology of the rosário suite
(Sociedade Brasileira de Geologia, 2017-06) NOGUEIRA, Bruna Karine Correa; GORAYEB, Paulo Sérgio de Sousa; DANTAS, Elton Luiz; LEAL, Rafael Estumano; GALARZA TORO, Marco Antônio
The São Luís Cráton comprises an area between northeast Pará state and northwest Maranhão that exposes Paleoproterozoic granitic suites and meta-volcanosedimentary sequences. In the east of this geotectonic unit, about 70 km south of São Luís, there is a portion of the São Luís Craton, represented by the intrusive Rosario Suite (RS). This work is focused on rocks of this suite, including petrographic, lithochemical and geochronological studies to understand the crustal evolution of these granitoid rocks. The rock spectrum varies from tonalitic to granodioritic, quartz dioritic and granitic compositions, and there are partial structural and mineralogical changes related to deformation along transcurrent shear zones. The geochemical studies show granitic metaluminous compositions of the calc-alkaline series with I-type affinity typical of magmatic arc. Rare earth elements show marked fractionation and slight Eu positive or negative anomalies (Eu/Eu* = 0.82 to 1.1). Zircon U-Pb data provided consistent ages of 2165 ± 7 Ma, 2170 ± 7 Ma, 2170 ± 7 Ma, 2161 ± 4 Ma and 2175 ± 8 Ma, dating emplacement of these granitoids as Paleoproterozoic (Rhyacian). Sm-Nd isotopic data provided model ages (TDM) of 2.21 to 2.31 Ga with positive values of εNd +1.9 to +3.2 (t = 2.17 Ga), indicating predominantly Rhyacian crustal sources for the parental magmas, similar to those ones found in other areas of the São Luís Craton. The data, integrated with published geological and geochronological information, indicate the occurrence of an important continental crust formation event in this area. The Paleoproterozoic evolution between 2.17 and 2.15 Ga is related to the Transamazonian orogeny. The granitoids of the Rosario Suite represent the main phase of continental arc magmatism that has continuity in other parts of the São Luís Craton and can be correlated with Rhyacian accretionary magmatism in the northwestern portion of the Amazonian Craton that amalgamated Archean terrains during the Transamazonian orogeny
Acesso aberto (Open Access)
The Belterra Clay On The Bauxite Deposits Of Rondon Do Pará, Eastern Amazon
(Sociedade Brasileira de Geologia, 2018-09) NEGRÃO, Leonardo Boiadeiro Ayres; COSTA, Marcondes Lima da; POELLMANN, Herbert
Bauxite deposits in the Amazon region are commonly covered by yellowish clays which can reach up to 25m thick, known as Belterra Clay (BTC). In Rondon do Pará, Eastern Amazon, BTC is 13m thick and covers world-class bauxite reserves. Three pilot bauxite mines were investigated in Rondon do Pará for an initial characterization of the local BTC. In discordant contact with the lateritic profile, the BTC has reddish brown colors at its base to ocher tones towards the top. It has a massive structure with silt-clayey texture and nodular bauxitic fragments at its base. Rietveld mineral quantification of the material attests that it is dominated by kaolinite, with goethite, gibbsite, hematite, anatase and residual quartz. The thermal behavior of the material also confirms its mineralogical composition. Kaolinite is of low structural order, which was considered the main difficulty in the application of the Rietveld method. Goethite has up to 33 mol% of Al. As observed by scanning electron microscopy (SEM), the minerals represent pseudo-hexagonal crystals measuring from 150 to 700 nm. The BTC in the studied area is correlated to BTC on others bauxitic deposits of the Amazon region, suggesting this material experienced the same genesis and geological evolution, probably during the Pliocene.
Acesso aberto (Open Access)
Holocene history of a lake filling and vegetation dynamics of the Serra Sul dos Carajás, southeast Amazonia
(Academia Brasileira de Ciências, 2017-08-24) GUIMARÃES, José Tasso Felix; SAHOO, Prafulla Kumar; SOUZA FILHO, Pedro Walfir Martins e; FIGUEIREDO, Mariana Maha Jana Costa de; REIS, Luiza Santos; RODRIGUES, Tarcísio Magevski; SILVA, Marcio da Silva
Down-core changes in sedimentary facies, elemental geochemistry, pollen, spore, δ13C, δ15N and radiocarbon records from a filled lake, named R4, of the Serra Sul dos Carajás were used to study the relationship between the paleomorphological and paleoecological processes and their significance for Holocene paleoclimatology of the southeast Amazonia. The sediment deposition of the R4 lake started around 9500 cal yr BP. Increase of detrital components from 9500 to 7000 cal yr BP suggests high weathering of surrounding catchment rocks and soils, and deposition into the lake basin under mudflows. At that time, montane savanna and forest formation were already established suggesting predominance of wet climate. However, from 7000 to 3000 cal yr BP, a decline of detrital input occurred. Also, forest formation and pteridophytes were declined, while palms and macrophytes were remained relatively stable, indicating that water levels of the lake is likely dropped allowing the development of plants adapted to subaerial condition under drier climate conditions. After 3000 cal yr BP, eutrophication and low accommodation space lead to high lake productivity and the final stage of the lake filling respectively, and forest formation may has acquired its current structure, which suggests return of wetter climate conditions.
Acesso aberto (Open Access)
Floods and social vulnerability: study on the Xingu river in Altamira/PA
(Associação Nacional de Pós-Graduação e Pesquisa em Ambiente e Sociedade, 2018-03-11) FRANCO, Vânia dos Santos; SOUZA, Everaldo Barreiros de; LIMA, Aline Maria Meiguins de
The objective of this research was to classify the social vulnerability in Altamira-PA, considering the occurrence of seasonal floods and the future scenario of stabilization of the water level in the flood quota. The Social Vulnerability Index was determined by using fluviometric station data provided by ANA and socioeconomic variables from IBGE. The results indicate a moderate to low vulnerability that does not reflect the socio-spatial environment of the area, where the alert level of 6 m is recurrently exceeded during the floods of the Xingu river. The Belo Monte hydroelectric power plant will ensure the maintenance of the level of floods, which implies in the demand of urban planning that can reduce the liabilities generated by both the maintenance of wetlands, and for the extensive relocation of people, in addition by studies that assess the influence and consequence of extreme events in the region.
Acesso aberto (Open Access)
Variação temporal do efluxo de CO2do solo em sistemas agroflorestais com palma de óleo na Amazônia Oriental
(Instituto Nacional de Pesquisas da Amazônia, 2016-03) SILVA, Carolina Melo da; VASCONCELOS, Steel Silva; OLIVEIRA JUNIOR, Moisés Cordeiro Mourão de; KATO, Osvaldo Ryohei; SILVA JUNIOR, Alberto Cruz da; CASTELLANI, Débora Cristina
The soil carbon dioxide (CO2) efflux dynamics and its controlling factors of Amazonian agroforestry systems are poorly understood. The objective of this study was to evaluate the temporal variation of soil CO2 efflux in oil palm-based agroforestry systems and the relation between efflux and biotic (microbial and total soil carbon, microbial respiration, fine roots, individual components of agroforestry systems (AFS)) and abiotic factors (soil moisture and temperature). The measurements were taken during the less rainy (December 2010) and rainy (May 2011) periods. The soil CO2 efflux was highest during the rainy season, probably due to increased microbial activity influenced by climatic factors coupled with biotic factors. The soil CO2 efflux correlated positively with soil moisture and microbial biomass carbon and negatively with soil temperature and metabolic quotient, but these correlations were weak. The soil CO2 efflux was sensitive to the type of agroforestry system and to rainfall seasonality.
Acesso aberto (Open Access)
Growth and survival of Sclerolobium paniculatum vogel and the relationship between rainfall and the increment in diameter at different planting spacings
(Universidade Federal do Pará, 2016-06) NARDUCCI, Tainah Silva; YARED, Jorge Alberto Gazel; BRIENZA JÚNIOR, Silvio
Sclerolobium paniculatum Vogel is a species that has good potential for reclamation of degraded soils. The aim of the investigation was to evaluate the growth and survival of the species and the influence of rainfall on growth in diameter as a function of different spacings (4 m x 2 m, 4 m x 3 m, and 4 m x 4 m). The results indicate that the temporal analysis (period from November 2007 to August 2013) detected significant differences (p ≤ 0.05) in height between the 4 m x 2 m and 4 m x 4 m spacings, while no significant difference in diameter was found between the 4 m x 2 m and 4 m x 3 m spacings. However, the statistical differences did not persist when the data was analyzed at seven and half years old. Regarding survival, a significant difference was observed only between the 4 m x 4 m spacing and the others, with superiority to the former. A strong correlation was found between rainfall and the increment in diameter of individuals in the broader spacings (R = 0.80 in the 4 m x 3 m spacing and R = 0.77 in the 4 m x 4 m spacing), while in the denser spacing the correlation was moderate (R = 0.56 in the 4 m x 2 m spacing). Since the spacings adopted did not influence tree growth by the end of the period, the choice will depend on other factors such as survival and costs of implementation and forestry management. Plantations in regions with larger rainfall amplitude may benefit the productivity of the species.
Acesso aberto (Open Access)
Ictiofauna de igarapés de pequenas bacias de drenagem em área agrícola do Nordeste Paraense, Amazônia Oriental
(Universidade Federal do Pará, 2012-06) CORRÊA, Jean Michel; GERHARD, Pedro; FIGUEIREDO, Ricardo de Oliveira
Stream fish communities can show spatial and temporal patterns, which can be revealed by species association or species groups as well as by species preference to certain habitats. The reduced number of studies and the scarce knowledge on the aquatic fauna in the Amazon results on an under-estimative upon stream fish fauna diversity. In this study, a survey at three small Amazonian catchments located in family agriculture areas, a total of 2,117 individuals were collected, belonging to seven orders, 13 families, 27 genera and 43 species. The most abundant species in all samples was Hyphessobrycon heterorhabdus, totaling 337 individuals, followed by Bryconops melanurus, with 326 individuals. The species richness was highest in a Pachibá stream reach, with 21 species. Simpson’s diversity index in a Cumaru stream reach showed the highest species dominance with a value of 0.43, while Shannon’s diversity index showed that the Pachibá stream lowest reach, had the greatest diversity with a value of 2.39. Iguanodectes rachovii was the most constant species, occurring in 50% of samples. Therefore, as a response to habitat size, the intermediate stream reaches presented the highest species diversity. Our study showed that agricultural catchments dominated by smallholder farmers can bear a reasonable stream fish diversity.
Acesso aberto (Open Access)
Chemical analysis of rainfall and throughfall in the Tapajós National Forest, Belterra, Pará, Brazil
(Universidade Federal do Pará, 2015-06) OLIVEIRA JUNIOR, Raimundo Cosme de; KELLER, Michael Meier; RAMOS, Jose Francisco da Fonseca; BELDINI, Troy Patrick; CRILL, Patrick Michael; CARMARGO, Plinio Batista de; HAREN, Joost van
The Tapajós National Forest (FLONA Tapajós) has 600,000 hectares of protected forest, and is situated 50 km south of the city of Santarém, Pará, Brazil, a port city of 250,000 inhabitants that is located at the confluence of the Tapajós and Amazon Rivers. There is a lot of farmland in the region, which offers many opportunities to study changes in land use. Selective wood harvesting is one type of land use that is particularly important to the economy of Santarém. Wet and dry deposition of organic material can be an important source of nutrients for plants, and this is especially true when the soil is poor, which is the case in Santarém-Belterra plateau region, the study area of this research. In this region, the natural atmospheric deposition of nutrients is often enhanced by the burning of biomass, which releases a large part of the above-ground biomass nutrients into the atmosphere. The objectives of this study were: 1 - estimate the total wet deposition via direct precipitation and through the canopy, including dry deposition; 2 - verify potential sources of nutrients found in the total wet deposition and dry deposition; and 3 - investigate the effects of coverage vegetation on nutrient content in precipitation and throughfall. The study was conducted in FLONA Tapajós at km 67 of Santarém- Cuiabá Highway, south of the city of Santarém. The study area consisted of a portion of 100 x 100 m transects divided into 10 x 10 m plots. The area was located next to a meteorological tower 65 m tall that measures various climate parameters such as rainfall, wind speed and direction, solar radiation, temperature and humidity, among others. Direct precipitation (PD) and internal precipitation (IP) collectors consisted of 2 L polyethylene bottles with a 115 mm diameter funnel. Samples were collected weekly from April 2003 to March 2006. The volume of the sample was measured individually for each collector (25 traps for internal precipitation and 4 for direct precipitation). The conclusions that can be drawn from this study are: 1 - the dry season has the highest variation in ion flux; 2 - seasonality has a strong influence on the concentration of basic cations; 3 - dry deposition is one of the most important ways that nutrients are acquired in FLONA Tapajos; 4 - there is a significant inflow of nutrients Cl and Na due to intensive grain farming nearby; 5 - dry deposition is the most important process for the enrichment of water that reaches the forest floor; 6 - principal component analysis facilitates the interpretation and characterization of rainwater and in this study shows the influence of anthropogenic sources such as agriculture, biomass burning, and dust.
Acesso aberto (Open Access)
Expansão urbana da Região Metropolitana de Belém sob a ótica de um sistema de índices de sustentabilidade
(Universidade Federal do Pará, 2016-09) VIEIRA, Ima Célia Guimarães; PEREIRA, Fabiana da Silva
The metropolitan area of Belém (RMB) contains 1/3 of the population of Pará State, Brazil, and its recent expansion has caused a number of social and environmental problems that undermine access to infrastructure and services and also impact other factors that influence urban sustainability. In recent years, various methodologies for assessing the sustainability of cities have been proposed, but the challenges of incorporating a multidimensional approach in the evaluation of urban sustainability are still enormous. In this work, we applied the Urban Sustainability Index System (SISU) to the RMB in order to analyze the levels of sustainability of the municipalities that constitute this metropolitan area and to verify the limitations and challenges in applying this method of measurement in the Amazon region. Seven indicators were used for the environmental quality index (IQA), and four for the political institutional capacity index (ICP) and the municipal human development index (IDHM). The results show that there is little variation in the IQA and IHDM indices, and the least-populated municipalities such as Santa Barbara and Benevides have better IQAs, while larger-populated municipalities, such as Belém and Ananindeua, have better IDHMs. However, it is in relation to ICP that this metropolitan area has the highest inequality, thus reflecting the need for the institutional and political empowerment of this region.
Acesso aberto (Open Access)
Zoneamento da bacia hidrográfica do rio Moju (Pará): usos da água e sua relação com as formas de uso e cobertura do solo
(Universidade Federal do Pará, 2017-08) FERREIRA, Susane Cristini Gomes; LIMA, Aline Maria Meiguins de; CORRÊA, José Augusto Martins
The Moju River Basin presents different patterns of land use resulting from a historic expansion of the agricultural and extractive sector in the state. It is embedded in the area of developmental projects in the region, with emphasis on the palm oil productive chain. In the present work, a zoning of the Moju River Basin has been carried out, evidencing the interconnection between the land use and land cover and the water use, showing the pressures on the natural resources that the basin is undertaking. The zoning is a product resulting from the association between land use and land cover mapping, and the categories of water users of the municipalities that compound the basin. The results showed that the greatest water user grant has industrial purpose, with underground extraction massively than the superficial, where the palm oil industry has the highest water use grant. Only a small number of inhabitants are served by water distribution and there are high rates of loss in the distribution system. The Alto Moju sub-basin suffers high pressure on its natural resources. We noticed that the basin as a whole has most of its territory covered by forest, although pasture and secondary vegetation are also expressive. In general, we observed that the biggest challenge is to align the management of water resources and efficient land use.
Acesso aberto (Open Access)
Evasion of CO2 and dissolved carbon in river waters of three small catchments in an area occupied by small family farms in the eastern Amazon
(Universidade Federal do Pará, 2017-08) FIGUEIREDO, Ricardo de Oliveira; MARKEWITZ, Daniel; KRUSCHE, Alex Vladimir; COSTA, Fabíola Fernandes; GERHARD, Pedro; ROSA, Maria Beatriz Silva da
CO2 effluxes from streams and rivers have been hypothesized to be a critical pathway of carbon flow from the biosphere back to the atmosphere. This study was conducted in three small Amazonian catchments to evaluate carbon evasion and dynamics, where land-use change has occurred on small family-farms. Monthly field campaigns were conducted from June 2006 to May 2007 in the Cumaru (CM), Pachibá (PB) and São João (SJ) streams. Electrical conductivity, pH, temperature, and dissolved oxygen measurements were done in situ, while water samples were collected to determine dissolved organic carbon (DOC) and dissolved inorganic carbon (DIC) concentrations, as well as carbon dioxide partial pressures (pCO2) and CO2 evasion fluxes. Instantaneous discharge measured by a current meter was used to calculate DOC fluxes. Considering all the sites, DOC, DIC, pCO2, and CO2 flux measurements ranged as follows, respectively: 0.27 - 12.13 mg L-1; 3.5 - 38.9 mg L-1; 2,265 - 26,974 ppm; and 3.39 - 75.35 μmol m-2 s-1. DOC annual flux estimates for CM, SJ and PB were, respectively, 281, 245, and 169 kg C ha-1. CO2 evasion fluxes had an average of 22.70 ± 1.67 μmol m-2 s-1. These CO2 evasion fluxes per unit area were similar to those measured for major Amazonian rivers, thus confirming our hypothesis that small streams can evade substantial quantities of CO2. As secondary vegetation is abundant as a result of family farming management in the region, we conclude that this vegetation can be a major driver of an abundant carbon cycle.
Acesso aberto (Open Access)
Síntese de zeólita do tipo faujasita: comparação entre caulim beneficiado e caulim flint
(Universidade Federal do Pará, 2015-06) ROCHA JUNIOR, Carlos Augusto Ferreira da; ANGÉLICA, Rômulo Simões; NEVES, Roberto de Freitas
The main purpose of this work is the synthesis of faujasite zeolite using three different kinds of kaolin from the Amazon region, Brazil: two kaolin from the beneficiation process for paper coating and hard or flint kaolin, a non-processed kaoling from the mining site. Analysis of the reaction products of kaolin showed the formation of faujasite zeolite. Flint kaolin showed a lower potential with respect to zeolitization ratio Si/Al equal to 2, compared to processed kaolins, probably related to the iron present in the structure. New results show a complete change in the formation of faujasite, which turns to be the main mineralogical phase after iron removal.
Acesso aberto (Open Access)
Sílica gel obtida de escória de alto forno: Marabá, Pará
(Universidade Federal do Pará, 2015-09) REBELO, Monaliza Maia; NASCIMENTO, Lidiane Diniz do; CORRÊA, José Augusto Martins
Silica gel with similar properties to commercial silica was obtained from blast furnace slag (EAF) using digestion with hydrochloric acid. The EAF-silica was obtained and characterized by different techniques. The results showed that the EAF-silica obtained was amorphous, with 99.7% purity and specific area 282 m2/g. It presented high hydrophilic character (12.27%), with constitution water of ~ 6.18%, which was confirmed by mass loss in thermogravimetric analysis. The EAF-silica particles had micrometric sizes (< 1 µm) with aggregates, unimodal size distribution and D50 7.0 µm.
Acesso aberto (Open Access)
Caracterização química e mineralógica de birnessita natural da Mina do Azul (Província Mineral de Carajás, Brasil) e seu análogo sintético (K-OL-1) obtido pelo método sol-gel
(Universidade Federal do Pará, 2016-06) FIGUEIRA, Bruno Apolo Miranda; ANGÉLICA, Rômulo Simões; COSTA, Marcondes Lima da; MERCURY, José Manuel Rivas; SANTOS, Manoel Roberval Pimentel dos; POELLMANN, Herbert
This paper presents a comparative chemical and mineralogical study of birnessite (BIR-AZ) collected from Azul mine (Carajás Province, Brazil) and its synthetic analogous synthesized by sol-gel method. The products were characterized by X-ray diffraction, FT-Raman spectroscopy, thermal analysis (TG-DTA), scanning electron microscopy (SEM) and ICP-MS techniques. The results obtained confirm the presence of well-defined layer structures having monoclinic system, C2/m space group and the unit cell parameters are: BIR-AZ, a = 5.148 Å; b=2.843 Å, c=7.175 Å, and β = 100.75º; K-OL-SG, a = 5.150 Å; b = 2.846 Å, c = 7.214 Å, and β= 101.29º. The birnessite from Azul mine ores shows thermal stability up to 600 ºC, whereas its synthetic analogous, above 900 ºC. FT-Raman bands at 635, 570 and 410 cm-1 were identified and attributed to the Mn-O and K-O bond deformations in the birnessite structure. SEM images reveals that the manganese oxide mineral consist of platy packed particles of about 1 to 5 µm. By contrast, the morphology of the synthetic compound displays randomly arranged globules (<1 µm).