Programa de Pós-Graduação em Geologia e Geoquímica - PPGG/IG

URI Permanente desta comunidadehttps://repositorio.ufpa.br/handle/2011/2603

O Programa de Pós-Graduação em Geologia e Geoquímica (PPGG) do Instituto de Geociências (IG) da Universidade Federal do Pará (UFPA) surgiu em 1976 como uma necessidade de desmembramento do então já em pleno desenvolvimento Curso de Pós-Graduação em Ciências Geofísicas e Geológicas (CPGG), instalado ainda em 1973 nesta mesma Universidade. Foi o primeiro programa stricto sensu de Pós-Graduação (mestrado e doutorado) em Geociências em toda Amazônia Legal. Ao longo de sua existência, o PPGG tem pautado sua atuação na formação na qualificação de profissionais nos níveis de Mestrado e Doutorado, a base para formação de pesquisadores e profissionais de alto nível. Neste seu curto período de existência promoveu a formação de 499 mestres e 124 doutores, no total de 623 dissertações e teses.

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Acesso aberto (Open Access)
Adequação de método para avaliação de risco de contaminação ambiental em áreas de estocagem de combustíveis
(Universidade Federal do Pará, 2002-02-28) CHAVES, Cláudio Cezar Cunha de Vasconcelos; CORRÊA, José Augusto Martins; http://lattes.cnpq.br/6527800269860568
Acesso aberto (Open Access)
Adsorção de cromato em materiais sintetizados a partir de rejeito de caulim do rio Capim
(Universidade Federal do Pará, 2008-05-13) MORAES, Milena Carvalho de; LEMOS, Vanda Porpino; http://lattes.cnpq.br/1829861620854008
Industrial and domestic waste cause serious problems for the environment. Industries treatment of kaolin have been deposited reject in large lakes of sedimentation and this has caused accidents as occurred in august/2007 and February/2008. The large volume of kaolin in the lakes sedimentation invaded lakes and rivers from Rio Capim, Para region. This fact resulted in the pollution of waters and death of fish. This problem can be minimized with the use of kaolin reject (KR) in the synthesis of new materials. In this work was used KR treated with organic acid (glycine at concentrations of 5%, 10% and 15% , being obtained the adsorbents: KR-gly-5, KRgly-10 and KL-gly-15, respectively) and mixture NaClO4:HClO4 (proportions 1:50 and 1:75, being obtained the adsorbents KR-NaClO4:HClO4-1:50 and KR- NaClO4:HClO4- 1:75, respectively) and KR as source of Si and Al in the synthesis of zeolites. The materials were characterized by chemical composition and XRD, FTIR, DTA-TG and SEM data. These materials were studied in adsorption process for CrO4 2- from aqueous solutions. The results obtained indicate that the CrO4 2- is adsorbed by kaolin reject and other materials from KR followed this order: KR-gly-10> KR-gly-5>KR-gly-15>KG> KR- NaClO4:HClO4- 1:75> zeolites.
Acesso aberto (Open Access)
Adsorção simultânea de íons níquel, zinco e cobre em sedimentos argilosos da Formação Solimões no estado do Acre
(Universidade Federal do Pará, 2011-09-02) CARDOSO, Vivian Mariana Miranda; LEMOS, Vanda Porpino; http://lattes.cnpq.br/1829861620854008
Torrential rains in the Amazon region provide large leaching of micronutrients, which can be controlled from the adsorption reactions of micronutrients in clay minerals. Studies on the geochemical properties of sediment containing high concentrations of clay minerals in the adsorption reactions of micronutrients is a research topic of great importance considering the proven use of clay minerals with a wide range of applications in various processes and procedures adsorption, involving the remediation of sediment, purification of air and water. In order to make contributions on the physical and chemical properties of soils and applicability of the Solimões Formation from Acre State was carried out a study to simulate natural competitive adsorption of micronutrients cobre, níquel e zinco in different adsorbents sites present in these sediment and to evaluate the influence of the attributes mineralogical, chemical and physico-chemical from these adsorption processes. Preliminary data on the mineralogy of soil samples allowed to select four stations distributed among four named as H1RA, H6B, H23A H9F and located along the BR 364 and BR 317, as well as outcrops in the river Acre. Analyses of samples were performed by XRD (using the powder in the range 2θ=o 5-75 ; analysis of clay fraction in sheets oriented air-dried in an atmosphere of ethylene glycol o and heated at 550 ° C (2θ = 3 -35 ) analysis total chemical by ICP-OES; element analysis exchangeable and available to determine parameters of soil fertility. In adsorption experiments the equilibrium concentrations of cobre, níquel and zinco were determined by AAS. We used the models of Langmuir isotherm, Sips, Toth, Temkin Rendlich-Petersen and the fit of the experimental data of adsorption. The results indicated that the samples present as major minerals quartz and clay minerals of the smectite group, mica and kaolinite mineral and the 14th (H6B) preliminarily identified as interstratified mica-chlorite smectite-mica or chlorite-vermiculite. The other minerals identified in the samples were gypsum (H1RA), microcline (H6B and H9F) and albite (H9F). The average chemical composition is represented by 60.99% SiO2, 15.91% Al2O3, 5.84% of Fe2O3, 2.21% K2O, 0.34% of Na2O, 1.26% MgO, 0.86% CaO and 0.86% TiO2. The following ranges were obtained for the parameters of fertility: pHH2O = 5.24 to 8.36; pHKCl = 3.16 to 7.02; CTCefetiva = 3.37 to 25.42 cmol c / kg;% V (base saturation) = 83.08 to 97.63; saturation% Ca = 4.28 to 69.21; saturation% = 11.32 to 76.42 Mg, K saturation% = 2.32 to 17.32;. In the adsorption experiments were obtained the following ranges for the amount of each element adsorbed (mg / g) in soil samples selected: Cu) from 91.30 to 147.46 in H1RA, 47.25 to 83.93 in H6B , 67.13 to 137.36 in H9F; 73.01 to 141.35 in H23A, Ni) from 49.97 to 93.81 in H1RA; 42.51 to 113.44 in H6B; 62.52 to 134.86 in H9F; 54.13 to 172.58 in H23A, Zn) from 50.11 to 104.50 in H1RA, 44.31 to 64.12 in H6B; 60.21 to 89.91 in H9F; 73.84-135 , 60 in H23A. In these experiments was obtained the following values for the initial pH of the aqueous suspensions of samples in H1RA pHinicial=3.88 to 5.38; in pHinicial H6B = 2.71 to 3.27; H9F in pHinicial = 3.16 to 4, 24 and in pHinicial H23A = 2.61 to 3.29. The values of pH equilibrium were 4.38 to 5.2 in the H1RA sample, 2.71 to 3.16 in H6B; 3.24 to 4.2 in H9F; 2.51 to 3.14.in H23A. It was concluded that the sediment samples analyzed have suitable properties adsorptive for simultaneous retention of Cobre, níquel and zinco in water; the samples with montmorilonite (station H23A) and mineral 14A (H6B) present adsorption of metals transition at pH values between 2.5 and 3.1. The samples H1RA H9F with different groups of clay minerals (smectite, kaolinite and mica) the adsorption of transition metals occurs at pH values between 3.2 to 5.5. The ionic strength increases with decreasing pH . The best isotherm models to describe adsorption processes of Cobre, níquel and zinco in sediment samples were the Langmuir and Sips models. The values of ns Sips indicated that the majority of adsorption systems fall between the homogeneous heterogeneous systems. The equilibrium data and thermodynamic processes of simultaneous interaction between these ions and mineral adsorbents indicated that the processes are favorable, spontaneous and the type of adsorption is specific (chemical adsorption) with the formation of inner sphere complexes.
Acesso aberto (Open Access)
As águas subterrâneas de Belém e adjacências: influência da Formação Pirabas e parâmetros físico-químicos para medidas de qualidade
(Universidade Federal do Pará, 1996-04-08) SAUMA FILHO, Michel; LIMA, Waterloo Napoleão de; http://lattes.cnpq.br/1229104235556506
In the Metropolitan Region of Belém (PA) the water supply to the population comes from springs (physiographic area of Utinga) and from a network of positional tube wells, in general, in more remote urban areas or where pumping is precarious. This work evaluates the groundwater used in the Metropolitan Region of Belém, correlating data of physical, physical-chemical and chemical parameters, in an attempt to compose an understandable picture about the quality of these waters, and to verify the influence that they suffer from the geological units in which they are located. the aquifers that preserve them are located. To carry out the work, water samples were collected in two different seasonal periods: dry and rainy. After exhaustive consultation of the files of companies, institutions and researchers, 17 tubular wells were selected, 9 in Belém, 5 in Icoaraci, 2 in Mosqueiro and 1 in Ananindeua (Annex A). The most frequent turbidity indices were between 9 and 14 units (ppm of SiO2), but some wells showed higher values (33, 41 and 71 ppm of SiO2. Only in some cases, this turbidity can be immediately correlated with the silica content obtained by chemical analysis. The most frequent color measurements are in the range from zero to 7.5 U.C., with the zero index predominating. However, some wells showed a value above 100 U.C. and others, less frequent, with indices varying between 20 and 60 U.C. The pH and electrical conductivity were quite different parameters. Thus, the highest pH and electrical conductivity indices were verified in the aquifers of the Pirabas Formation. In these cases, the pH was around 6 .4 to 7.6 and conductivity between 231 and 362 µS/cm, with a discontinuity at 87.5 µS/cm, also attributed to a well associated with the aforementioned Formation. More acidic waters (pH below 6.38 and above of 4.01) are certainly attributed to the aquifers of the Barreiras and Post-Barreiras Group. The chemical constituents, notably the contents of Ca2+, Mg2+, Na+ and K+, are consistent with the interpretation of the numerical values of pH and electrical conductivity. Without exception, the concentrations of Ca2+ are higher than those of the other cations, establishing a decreasing order according to Ca2+> Mg2+> Na+>K+, with some inversion between Na+ and Mg2+. The highest concentrations of Ca2+ (soon followed by Mg2+) result from the dissolution of carbonates present in the Pirabas limestone. In fact, confirming this assertion, the concentrations of HCO-3 are also much higher than the concentrations of Cl- and SO2-4. It is to be expected, therefore, that the dissolution of Pirabas sediments produces higher concentrations of Ca2+ and HCO-3. The silica and iron contents also discriminate such waters. In general, higher silica contents correspond to greater depths, as would be expected, taking into account the action of chemical weathering on silicate minerals. As for iron, this constitutes a differentiating parameter of the waters of the Pirabas Formation, almost always at much lower levels than the corresponding values associated with the Barreiras and Post-Barreiras aquifers, with, however, exceptions, in which appreciable indices of iron related to Pirabas sediments. It should be noted that the Pirabas Formation appears in the Metropolitan Region of Belém almost always at depths greater than 100 m, although there are records of smaller depths, but these are apparently rarer situations, as is the case with well number 3. , on the University Campus, near the Guamá River, with a depth of 76 m, and the 94 m well of the Museu Paraense Emílio Goeldi, in the central area of the city (Annex A). The exhaustive consultation of the aforementioned archives of institutions, companies and researchers led to the realization that many tubular wells installed in the urban area use water associated with the Barreiras and Post-Barreiras aquifers, where the pH values are almost always, below 6 units, and electrical conductivity measurements rarely reach 100 µS/cm. Finally, it appears that there is a need for greater investments in order to increase the prospection and use of groundwater in the region, as these, in addition to dispensing with treatment prior to distribution, are still a source of resources, not dimensioned, but of great potential.
Acesso aberto (Open Access)
A ametista de Pau d' Arco e Alto Bonito no Pará e a do Alto Uruguai no Rio Grande do Sul
(Universidade Federal do Pará, 1998-03-23) CASSINI, Carlos Tadeu; COSTA, Marcondes Lima da; http://lattes.cnpq.br/1639498384851302
Acesso aberto (Open Access)
Uma análise de cluster via CiteSpace a propósito da espectrometria WDXRF para geocientistas (2001-2021)
(Universidade Federal do Pará, 2023-08-17) CASTANHO, Rebeca Soares; PAZ, Simone Patrícia Aranha da; http://lattes.cnpq.br/5376678084716817
The present bibliometric analysis addresses the use of Wavelength Dispersive X-Ray Fluorescence (WDXRF) spectrometry in geochemical analysis to evaluate scientific trends over a twenty-year period, from 2001 to 2021, using the academic and free bibliometric tool, CiteSpace. For this purpose, 941 international scientific articles involving WDXRF were collected from the Web of Science (WoS) platform using the search terms "wdxrf" or "wavelength dispersive x-ray fluorescence". The data analysis was divided into two parts: the first part aimed to understand and interpret the quantitative aspects of the scientific production related to the technique, while the second part involved a co-occurrence analysis of keywords from the retrieved works. Despite fluctuations, there has been a constant increase in the number of articles related to this spectrometry technique, with 2020 being the year with the highest productivity in the historical series (105 publications). The United States of America leads the country rankings (110 articles); however, the relatively homogeneous distribution of these studies reveals that WDXRF is a widely disseminated technique worldwide. Brazil ranks among the top ten most influential countries in this field, occupying the eighth position with 59 publications. The journal X-Ray Spectrometry, with 82 articles, stands out as the primary venue for the dissemination of research on this analytical technique. In total, 569 keywords were found, connected by 2002 co-occurrence links. The term "trace element" denotes a solidified but always relevant interest in the use of WDXRF for this level of chemical analysis. On the other hand, "nanoparticle" is the keyword with the highest citation explosion over the past two decades, particularly between 2015 and 2021, highlighting a more recent trend in the elemental characterization of nanostructured compounds. The CiteSpace program identified 13 thematic groups, with five being the most notable in the application of this instrumentation: nanomaterial characterization (cluster #0), trace-level heavy metal analysis (cluster #1), chemical speciation (cluster #2), analysis of particulate matter on filters (cluster #5), and provenance of historical ceramics (cluster #6). In summary, it can be concluded that the chemistry of geological materials does not constitute a narrowly defined body of studies concerning WDXRF. Instead, it represents a scientific frontier that expands through interdisciplinary approaches, providing new and integrated methodological approaches to geoscientific research for those who delve into this technique.
Acesso aberto (Open Access)
Análise evolutiva da paisagem da serra Tepequém - Roraima e o impacto da atividade antrópica
(Universidade Federal do Pará, 2008-01-23) BESERRA NETA, Luiza Câmara; BORGES, Maurício da Silva; http://lattes.cnpq.br/1580207189205228; 1580207189205228; COSTA, Marcondes Lima da; http://lattes.cnpq.br/1639498384851302; 1639498384851302
The north area of Roraima State presents great diversity of geomorphologic featuresformed by dissected plateaus, limited by intermountain plain and relief with a plateau morphology that it is individualized in the extensive plain areas, e.g., of the mountain Tepequém. Since 1930s this was a site of intense activity of diamond extraction what printed changes in the landscape. The main objective of this study is to understand the dynamics evolution of the landscape of the mountain Tepequém under diamond extraction activity and the reason of its erosion susceptibility, being natural or anthropic. To reach these objectives, a description of profiles of soils and saprolitic rock, as well as lateritic profiles were accomplished. Samples of soils, altered rocks, laterites and coal were collected. Besides, width, depth, extension and directional alignment of the channels of the gullies measurements were carried out. The collected materials were submitted to the following analyses: grain size, by humid way; minerals identification by X-ray diffraction and SEM techniques; total chemistry analysis (major elements) by ICP-MS and content of organic matter, humidity and density of the soil measurements. Coal samples were submitted to radiocarbon analyses by AMS (Accelerator Mass Spectrometry). Appling the interpretation of optical images (Landsat-5/TM and Cbers-2/CCD) and the cartographic base, maps of structural alignment, relief (altimetry and declivity), drainage and vegetation covering were also elaborated. The mountain Tepequém stand out among the landscape dominated by relief of hills, residual hills and plane-slightly wavy surfaces because of its rectangular-rhombic format and outline of steep scarps elaborated on sedimentary rocks of Paleoproterozoic. The drainage system of the area delineates parallel, angle-rectangular and faults standards. The relief and drainage morphology of the mountain Tepequém and its around area define a subordination to the structural arrangement E-W, NE-SW and NW-SE directions represented by normal and strike-slip faults. In the mountain Tepequém, the geomorphologic compartments are established by 575 to 670 m high plain intra-valleys surfaces bordered by less than 774m high hills and residual hills and edge slopes less than 1100m high. The bush grassy savanna dominates this landscape and recovers the edge scarps and extends along the regional plain. The ciliary forest covers small stains along the Cabo Sobral and Paiva rivers. This scenery was quite modified because of diamond extraction activity. However, with the decline of this activity, the ciliary forest recovers spontaneously, as the optical images of the last 22 years shows (1984, 1995 and 2006). Intra-valleys plains were developed on sandy soils constituted by medium and fine grain size sandy domains, sub-angles to sub-rounded poorly selected, with low cohesion and small quantity of organic matter. These soils are developed on saprolitic derived of sandstones and siltstones. Locally stone lines and colluvial are observed, usually on the saprolitic. Immature laterites are found in the center-north hills of the mountain Tepequém. Quartz, muscovite in sub-milimetric plates and kaolinite partially involving the grains of quartz are predominant in soils constitution, while the lateritic profiles are constituted by gibbsite, goethite and hematite, besides quartz and kaolinite. Laterite and quartz fragments constitute the stone lines. High concentrations of SiO2 confirm the essentially quartz-character of the soils, while the values of Al2O3, K2O, MgO, Fe2O3 and TiO2 are more expressive in the saprolitic zones, confirming the kaolinite, muscovite and hematite domain, derived of claystones and siltstones. The radiocarbon ages in coal obtained for the superficial materials (colluvial and stone lines) show that these materials were formed at least 3.822 years BP. The intermountain plains reveal in its landscape erosive features in the piping formations, dolines and gullies, developed in the lands with sandy to silt materials domain. The channels of gullies are mainly aligned in the directions NE-SW and NW-SE corresponding to the directions of fractures and faults that section the Tepequém Formation. The seemingly stabilized gullies are partially covered by ferns that grow on the side and bottom surfaces of the channel. The evolution of the landscape of the mountain of Tepequém specially the formation of its general internal structure involves the tectonic still in Proterozoic. The inherited morphology reflects in the steep scarps around as well as in the top such a great synclinorium. The evolution of the landscape of the mountain of Tepequém during Cenozoic is marked by formation of small hills, some of these protected by lateritic crusts suggesting registration of a humid and hot paleoclimate in Pleistocene, which can admit the installation of the drainage net. The erosive process of the fluvial courses allies with the high gradient favored the transport of part of the sediments to W-SW direction, contributing in the formation of the intermountain plains. The current scenery is marked by the erosive retaking favored by the sandy non-cohesive nature of the soils, ally to a paleorelief inclined to the valleys and strongly fractured and failed that causes a strong shallow surface stormflow propitiating the piping formations, dolines and then the gullies. Thus, the diamond extraction activity can contribute in the intensification of the gullies but, however, it was not the decisive factor. Therefore, the evolution of the landscape of the mountain Tepequém in Proterozoic and in Cenozoic until the present is due to the interaction of multiple processes involving the tectonic history, the weathering changes and the several erosion cycles, as well as the restricted sedimentation and the small anthropic contribution.
Acesso aberto (Open Access)
Análises sequenciais para o ouro em solo do salobo 3A, Serra dos Carajás
(Universidade Federal do Pará, 1989-06-07) FRANCO, Maria Esmeralda Bravo Esteves Bouça; RAMOS, José Francisco da Fonseca; http://lattes.cnpq.br/8189651755374537
The Salobo 3A area. in Serra dos Carajás in the State of Pará belongs to an elongated range. according to the WNW-E SE direction. of Archean age, which borders the northern flank of the Carajás syncline. This area has been the subject of several studies, with the aim of prospecting and extracting copper ores and using their by-products. The aim of this work is to investigate the distribution of gold in soils in the area of the Salobo 3A copper sulphide deposit. Eighteen samples were collected in horizontal and vertical profiles next to gallery G1 and another sixteen from wells PA-O8 and PA-23. Soil gold concentrations were determined according to the sequential partial opening of Gatehouse et al. (1977), which was supplemented by organic extraction. due to the low concentrations of this metal in soils. The phases considered separately were iron and manganese oxides and hydroxides (amorphous and crystalline), organic matter and clay mineral silicates and quartz. A particle size fraction < 120 mesh was chosen. to avoid the presence of larger metallic gold particles. In addition to sequential analysis. another 5 grams of the same sample were etched with HF+HCl04 and another 5 grams with HF+HCl04 followed by etching with aqua regia (Au-total). All results were compared with those obtained by the instrumental neutron activation analysis and with DOCEGEO analyzes performed through the aqua regia aperture. The main objective of this work is to show the suitability of sequential analyzes for gold in soils and, through the results obtained for the studied phases, to deepen the knowledge about the behavior of gold in a supergenic environment. Of these, it is worth noting the good correlation between the gold concentration determined in the organic matter and the Au-total concentration in the soil (or even only with aqua regia, or with values obtained by INAA). The study of the amount of organic matter related to the gold adsorbed on it seems to be in agreement with the mechanisms of mobility and transport of gold in a supergenic environment known so far. From the analyzes carried out, it is concluded that, in general, little gold is found in the native state, if the concentrations obtained by the partial extractions are compared with the Au-total concentration of the samples. This element is preferentially found in silicates (clay minerals and quartz), in organic matter and in goethite (in smaller amounts).
Acesso aberto (Open Access)
Aplicação de resíduos da mineração de bauxita na síntese de geopolímeros
(Universidade Federal do Pará, 2022-04-08) BARRETO, Igor Alexandre Rocha; COSTA, Marcondes Lima da; http://lattes.cnpq.br/1639498384851302; https://orcid.org/0000-0002-0134-0432
The process of extraction and beneficiation of bauxite deposits in the bauxite province of Paragominas/Rondon do Pará can generate large amounts of waste, mainly in two stages of the process: mining and processing. In the mining stage of the deposits, the “residue” comes from the removal of a thick layer of clay material (known as Belterra Clay). On the other hand, the “residue” from the beneficiation process is generated after the crushing, grinding and washing stages, which give rise to a large amount of clay material dispersed in a large amount of water. For the present study, it selected Belterra clay from the bauxite deposits of Rondon do Pará, a sample of Bauxite Washing Clay from the Hydro company and a sample of kaolin benefited from Imerys Company. The samples and geopolymers were characterized by X-ray Diffraction (XRD), X-ray Fluorescence (FRX), Gravimetric Thermal Analysis (TG), Differential Exploratory Calorimeter (DSC), Optical Emission Spectrometry with Coupled Plasma (ICP-OES) and Laser Particle Analyzer (APL). Geopolymers were synthesized from Belterra clay, microsilica and NaOH according to the Box-Benkhen design. Synthesis of geopolymers from Belterra clay and beneficiated kaolin was also carried out (a comparative study) using KOH and microsilica. Finally, geopolymers were synthesized from Bauxite washing clay with NaOH and microsilica according to the Doehlert design. In the study with only Belterra clay, the highest resistance result was 47.78MPa and the lowest result was 7.05MPa. In the comparative study between Belterra Clay and beneficiated kaolin, the best results of compressive strength were obtained with the beneficiated kaolin. The compressive strength results of the geopolymers synthesized from the Washing Clay ranged from 8.99 to 41.89MPa. These results demonstrate the positive potential of both samples for the synthesis of geopolymers that can be used as possible “Eco-friendly” substitutes for traditional materials, mainly ceramics and cement.
Acesso aberto (Open Access)
Aproveitamento dos resíduos cauliníticos das indústrias de beneficiamento de caulim da região amazônica como matéria-prima para fabricação de um material de construção (pozolanas)
(Universidade Federal do Pará, 2007-12-18) BARATA, Márcio Santos; ANGÉLICA, Rômulo Simões; http://lattes.cnpq.br/7501959623721607; https://orcid.org/0000-0002-3026-5523
The Capim and Jarí regions are the most important kaolin district in the Amazon region, with the largest Brazilian reserves of high whiteness kaolin for paper coating products. Kaolin is obtained from three companies (IRCC, PPSA and CADAM) which produce annually around 1,000 M ton kaolinite-rich wastes derived mainly from the centrifugation phase of the process. The sludge is disposed on artificial sedimentary lakes covering large areas. Another type of kaolin waste is related to a non-processed iron-rich hard or flint kaolin, that overlays the so-called soft kaolin horizon (the main ore). These wastes exhibit appropriate characteristics for the production of high-reactivity metakaolin because they are extremely fine and composed of mainly by kaolinite. The main purpose of this work is to evaluate the feasibility of using these wastes as raw materials to produce mineral admixtures for OPC concretes. The wastes were firstly characterized for x-rays diffraction, thermal analysis, infrared spectroscopy, x-rays fluorescence and SEM. Three heating temperatures were evaluated: 750ºC, 850ºC and 900ºC, followed by pozzolanic activity tests based on traditional mechanical assays using Portland cement and hydrated lime mortars, and “Chapelle” test. The results showed that the more reactive pozzolans are those produced at temperatures that gave rise to higher LOI. The optimum burning temperature to produce metakaolinite from the hard kaolin was obtained at 750ºC while those from the Rio Jari and Rio Capim wastes were at 850ºC and 900ºC. The main reason is related to differences in the amounts of defects from three different wastes. The flint kaolin and Rio Jari waste are mainly composed by a “high-defect” kaolinite while the kaolinite from Rio Capim waste is a “lowdefect” kaolinite. In concrete test using different pozzolans those with metakaolin from wastes improved the mechanical and durability properties in comparasion to silica fume, a industrially manufactured metakaolin and reference concretes.
Acesso aberto (Open Access)
Argamassas históricas de Belém do Pará.
(Universidade Federal do Pará, 2019-09-16) LOUREIRO, Alexandre Máximo Silva; ANGÉLICA, Rômulo Simões; http://lattes.cnpq.br/7501959623721607
The city of Belém, northern Brazil, known as the metropolis of the Amazon, was established on the banks of the Guajará Bay on January 12, 1616, with the denomination of Nossa Senhora de Belém do Grão-Pará, capital of the Grão-Pará province, now the state of Pará. Currently, Belém still has layers of lime mortar on its colonial and imperial buildings, which protect the secular structures and provide evidence of how this material was produced early in its history. Over the years, the deteriorating aspects identified in lime mortars, which damage both aesthetics and functionality, are related to the humidity, saline efflorescence, biological colonization, and/or anthropic actions. Once deteriorated, mortars require maintenance, consolidation, or replacement, which are difficult procedures that can lead to the use of inappropriate materials. Therefore, a good collect and characterization strategies of the original material is necessary for the restoration of historical monuments, because in studies focused on restoration science, the intervention strategy needs to include the use of building materials compatible with the original materials. Thus, the main objective of this doctoral thesis is to determine the characteristics and properties of historical mortars in Belém do Pará from the 18th and 19th centuries, as well as to propose a restoration mortars compatible with the historic mortars, which using industrial waste from Amazon Region. Therefore, this thesis was structured in three independent and complementary thematic articles, which addresses the topic of the historical mortars of Belém do Pará, since their characterization until the proposal of restoration mortars: 1) Investigation of the historical mortar of Belém do Pará, Northern Brazil; 2) How to estimate the binder: aggregate ratio from aerial lime-based historical mortars for restoration? and; 3) The use of industrial waste of the Amazon region in lime-metakaolin restoration mortars: compatibility assessment. Thus, the physical, chemical and mineralogical characteristics were determined, as well as the physical and mechanical properties of the historical material and the restoration material. The results of the historical mortars characterization pointing their main components, their functions and raw materials, besides indicating the analytical techniques used for binder: aggregate ratio quantification, which obtained good accuracy and reliability in your results. Moreover, the results show a wide range of characteristics and properties obtained through restoration mortars, which can serve as a benchmark for other studies or even for practical applications in historic masonry. Therefore, it was possible to identify the restoration mortars most compatible with the historical mortars of Belém do Pará, Northern Brazil.
Acesso aberto (Open Access)
Argila de Belterra das coberturas de bauxitas da Amazônia como matéria-prima para a produção de cerâmica vermelha
(Universidade Federal do Pará, 2018-01-10) BARRETO, Igor Alexandre Rocha; COSTA, Marcondes Lima da; http://lattes.cnpq.br/1639498384851302
The Amazon region holds the largest reserves of bauxite in Brazil, whose deposits are covered by a thick bundle of clay material, known as Belterra Clay (ABT). The wide distribution, superficial occurrence, therefore accessible, and clayey ABT nature have aroused the interest of this work in evaluating its technical viability for the production of red ceramics. For the present study, ABT was selected from the large bauxite deposits of Rondon do Pará, samples of the yellow soils from Mosqueiro, illitic clay and gibbsitic clays and one sample of the clayey siltstone. This clay and other materials used as additives were characterized by X-ray Diffraction (XRD), X-Ray Fluorescence (FRX) (CT), Spectrometric Thermal Analysis (TG), Differential Scanning Calorimete (DSC), Inductively Coupled Plasma Spectrometry (ICP-MS), Coupled Plasma Optical Emission Spectrometry (ICP-OES), Scanning Electron Microscopy (SEM) Laser Particle (APL). To determine the physical and mechanical properties, were produce specimens through different mixtures with the samples of Belterra clay and percentages (20, 30 and 40%) of the yellow soil, clayey siltstone, gibbsitic clays and illitic clay. The specimens were calcined at three different temperature moments (900, 1000 and 1200 ° C). Then, linear retraction, water absorption, apparent porosity, apparent density and bending rupture tension were measured. ABT is essentially kaolinite, having quartz, goethite, anatase and gibbsite as accessory minerals. The pure and simple ABT did not present favorable technological aspects for the production of ceramic products, however the same with addition of the yellow soil and clayey silt from the same region significantly improved the technological characteristics of the ABT.
Acesso aberto (Open Access)
Aspectos geoquímicos de gleissolos em pântanos salinos da região Bragantina, Pará
(Universidade Federal do Pará, 2011-06-08) CAMARGO, Paloma Maria Pinto; CORRÊA, José Augusto Martins; http://lattes.cnpq.br/6527800269860568
The knowledge about the nature of depositional processes in the tidal flats, where the salt marsh are included, is very important to understand the tropical coastal ecosystem. Evaporitic minerals, like in Sabkhas, are observed in Bragança salt marsh during the dry season. Halite is deposited on the surface of the soil and gypsum and pyrite precipitate in the subsurface via capillary action out of brines brought up from the water table. The pedogenic processes in the salt marsh where dominate by chemical reactions like halomorphism, hydromorphism, sufate reducing. The aim of this study is characterize the soil of Bragança salt marsh using the textural characteristics, mineralogical and geochemical composition of sediments. The sampling was performed in two transects located in both sides of the PA-458. Each transects have 3 profiles that arise 1 meter depth. The samples were collected by a dutch auger for augering shallow depths (20 cm). The granulometry of sediments was obtained with a laser granulometer and the mineralogical composition was performed by X-ray diffraction techniques. The sand grains were observed using a petrographic microscope with digital image capture. The neoformed minerals and silt+clay grains size were described using a scanning electron microscopy (SEM). In the soil were also studied the pH, electric conductivity, salinity, organic matter content, major, minor and trace elements using classical chemical methods, X-ray fluorescence and atomic absorption spectrometry. Gleysol present in salt marsh show silty-clayey grain size, massive texture, slightly sticky to sticky, very plastic to slightly plastic and friable to compact. Mineralogical it was composed of quartz, kaolinite, illite, smectite, pyrite, jarosite, polyhalite and halite. The pH values ranged from high acidity to acid and the lowest value was found in the depth of 70-90 cm (pH = 3.85), profile P4. Some profiles shown in the Zone 2, where pH is much acid, yellow to orange mottles which corresponds to pyrite oxidation. Based on composition of the adsorption complex of studied soil profiles, the profiles showed high CEC due to the large amount of organic matter and clay minerals. The dominance of Na+ and Mg2+, followed by Ca2+ and K+ assigning to soil eutrophic character. Only the profile P4, B transect, showed dystrophic character. All profiles shown high sodium concentration, characterizing the salt marsh soil as "Solonchak" and therefore may be classified as Salic Sodic Gleysol. The salt marsh soil contains high values of SiO2, Al2O3 and Fe2O3, which reflect its major minerals. Illite, smectite, polyhalite, halite and pyrite are characteristics of salt marsh environment, where the sedimentation occur under the influence of sea water which contributes to Na+, K+, Ca2+, and Mg2+. The presence of jarosite indicates the oxidation of sulfides. The high amount of Na2O reflect the strong evaporation rates under which the salt marsh environment is submitted, and support the neoformation of halite at different depths along a profile. The results and the field observations suggests that the new mineral phases are essentially the result of high evaporation rate, organic matter content, primary mineral phases.
Acesso aberto (Open Access)
Aspectos granulométricos, mineralógicos e químicos de sedimentos de praias (Barras em Pontal) do Rio Acre e sua relação com a fertilidade
(Universidade Federal do Pará, 2004-10-30) VIANA, Érica Cristina Acácio; COSTA, Marcondes Lima da; http://lattes.cnpq.br/1639498384851302
Acesso aberto (Open Access)
Aspectos mineralógicos geoquímicos da laterita niquelífera da área do Vermelho, Serra dos Carajás
(Universidade Federal do Pará, 1982-12-29) CORRÊA, Sandra Lia de Almeida; SCHWAB, Roland Gottlieb
The mineralogical-geochemical study of nickel-bearing laterite from the Vermelho area, Serra dos Carajás, was based on 64 samples obtained from a drill in the mother rock and a well in the alteration profile. The lateritic profile, developed on serpentinized ultrabasic rocks, consists of three distinct horizons; from the base to the top: saprolithic horizon, with more than 4 meters of thickness, clayey horizon, with 6.1 meters, and limonitic horizon with 8.3 meters. Mineralogically, the saprolitic horizon consists of serpentine, chlorite, quartz, hematite and goethite, the clayey horizon of smectite, chlorite and goethite and the limonitic horizon of quartz, goethite, hematite, chlorite and kaolinite. Maghemite is present from the base to the top of this profile. During the action of weathering, the main and trace elements underwent leaching, transport and reprecipitation processes, resulting in the concentration of these elements in the different horizons of the profile, with the exception of magnesium, which was leached to a large extent. Despite the low mobility of chromium in the lateritic medium, this element was leached from the saprolitic horizon and from there it enriches itself, thus behaving as a relatively mobile element. The profit and loss calculations were difficult to make because no element showed continuous relative enrichment from the bottom to the top of the profile. Considering the average contents of the horizons of the lateritic profile and fresh serpentinite, only iron and cobalt present continuous relative enrichment. The nickel concentration in the clayey horizon possibly occurred through an ion exchange process between the smectite and the level migrated by descending solutions, after its release from goethite. The parent rock contains 0.3% Ni, while the clayey horizon has an average content of 4.5% Ni. Cobalt and zinc were also strongly enriched during the laterization process. The cobalt was concentrated in the limonitic horizon, where it reaches an average content of about 0.1% by weight, thus suffering an enrichment of almost nine times in relation to its content in the mother rock. The distribution of cobalt in the lateritic profile is controlled by iron and manganese minerals. Zinc was concentrated in the saprolitic horizon, where it has an average content of approximately 0.05% by weight, enriching about 10 times its content in the mother rock.
Acesso aberto (Open Access)
Aspectos termodinâmicos relacionados com a gênese e alteração de minerais de cobre em clima tropical úmido (região da Serra dos Carajás-PA
(Universidade Federal do Pará, 1990-01-14) FERREIRA, Rosângela Sales; LIMA, Waterloo Napoleão de; http://lattes.cnpq.br/1229104235556506
Copper deposits belonging to the volcano-sedimentary sequence (Salobo 3 A and Bahia) and the Serra Verde supergenic enrichment deposit are objects of study in this work, located in the Carajás Mineral Province (Municipality of Parauapebas, State of Pará). For chemical-mineralogical characterization, we proceeded: (1) X-ray diffractometry; (2) chemical analysis (colorimetry and atomic absorption spectrophotometry); and (3) the use of stoichiometric calculation, providing data capable of contributing to the clarification of the geochemical behavior of copper species and associated minerals in weathering profiles. In order to examine in more detail the geochemical changes inferred in the geological environments of the three deposits (Salobo 3A, Bahia and Serra Verde), a theoretical study was carried out on thermodynamic parameters, compiled in the literature, and such data were manipulated in the calculation of free energies. of Gibbs and of the equilibrium constants of the reactions for the considered chemical systems. This study involved the equilibrium relationships between the minerals biotite (Fe), chlorite (Fe), montmorillonite (Fe), tremolite (actinolite), kaolinite, geothite, pyrite, chalcopyrite, bornite, brochantite, azurite, malachite and pseudomalachite, from the copper deposits in the Serra dos Carajás region. The objective was the elaboration of stability diagrams of these minerals. A brief experimental study was also carried out, by carrying out measurements of Eh and pH, in the laboratory, by dissolving the sampled material in distilled water, in order to frame such data in an Eh-pH diagram, existing in the scientific literature. , in an attempt to obtain information about the acidic, basic, oxidizing and reducing characteristics of the species contained in the samples under study. The theoretical thermodynamic study concerns the applicability of calculations related to the solubility product and the Gibbs free energy. The final composition resulting from the joint use of the experimental work with the theoretical investigation allowed to verify the stabilities of the detected mineral species, being possible to confirm the field observations. For Serra Verde, the thermodynamic calculations clearly demonstrated that the stability of the detected supergenic copper minerals grows in the order malachite-azurite-brochantite-pseudomalachite. The reactions suggested in the work reveal that both bornite and chalcopyrite underwent alterations in an oxidizing medium (positive and somewhat high Eh), producing the aforementioned supergenic minerals. For Salobo, this study shows the possibility of determining the stability fields of primary and altered silicates from the copper host rock, as well as the stability fields of copper and iron sulphides (bornite and chalcopyrite), enabling the formation of brochantite, which occurs locally in the study area. For the occurrence of Bahia, the stability field was determined in the same way as for Salobo, with chalcopyrite being found there in a disseminated form.
Acesso aberto (Open Access)
A associação geoquímica Au-As-B-W-Cu-(Sn) em solos, colúvios, crosta laterítica e gossans no alvo Águas Claras-Carajás
(Universidade Federal do Pará, 1997-05-07) COSTA, Newton Cunha da; COSTA, Marcondes Lima da; http://lattes.cnpq.br/1639498384851302; https://orcid.org/0000-0002-0134-0432
The studied area called Alvo Águas Claras, is located in the Mineral Province of Carajás, southwest of the State of Pará, which represents one of the largest mineral provinces in the world. It is an important area for gold research, which has been prospected since 1991 by DOCEGEO, a subsidiary of Companhia Vale do Rio Doce – CVRD. This target is located in a region of dense rainforest cover, whose geological profiles are highly weathered, showing similarities with the gold deposits described in several other regions of West Africa and Australia. In the Amazon region, the older lateritic profiles are undergoing intense alteration since the end of their formation in the Lower Tertiary, with consequent distribution of these profiles and formation of soils or colluviums. The objective of this work is the detailed study of the behavior of gold, on the surface of this truncated lateritic terrain, and its relationship with trace elements such as B, W, Sn and Cu, in latosols, colluviums and outcropping laterite-gossanic crusts in the area. Thus, a detailed geochemical and mineralogical study of this material was developed, in order to assist in the identification of geochemical signatures indicative of the primary nature of mineralizations and associated rocks, in addition to the evaluation of the dispersion and mobility of these elements during the transformations of the lateritic and gossans crusts. in latosols and colluviums, to establish criteria for geochemical prospecting of these bodies in deeply weathered regions. The work methodology consisted of a field phase, developed on the mineralized bodies denominated by DOCEGEO as Corpo da Anomalia Au/As and Corpo do F-23, with the objective of geological reconnaissance of the area, description of the units and collection of samples of surface. The samples collected were mostly oxisols, colluviums, lateritic crusts, gossans, in addition to host rocks (sandstones and siltstones) and quartz veins. The analytical treatment consisted of several phases such as: drying, quartering and separation of 200g aliquots for pulverizing and 100g for separating heavy and insoluble minerals from pre-selected samples, through the highest levels of boron and gold. Petrographic analyzes were performed using an optical microscope with reflected and transmitted light. All samples were submitted to X-ray diffraction analysis, where both the total sample composition and the different domains of complex samples and isolated minerals were analyzed. A detailed mineralogical study was carried out on tourmalines, involving the calculation and refinement of the unit cell parameters. Quantitative analyzes of the minerals, as well as detailed photographs, were carried out by Scanning Electron Microscopy, with Dispersive Energy System, involving gold particles and other associated heavy minerals. In the geochemical analyses, the following major elements were analyzed: Fe2O3, TiO2, P2O5 through colorimetry; SiO2 and loss on ignition (P.F.) by gravimetry; Al2O3 by titrimetry; Na, Mn, K, Mg by atomic absorption, and some trace elements including Au. In the statistical treatment of data, correlation studies were mainly used, based on Parson's correlation coefficient (r), through binary correlation diagrams, correlation matrices and dendrograms of cluster analysis in R-mode. Isovalue maps were made for Au, B, W, and As, in order to better visualize the surface dispersion of these elements. The geology of the area is characterized by different outcropping and sub-outcropping supergenic materials, which can be juxtaposed in the form of the following composite profile, from top to bottom: Soil horizon (latosol), Colluvium horizon, Lateritic crust and Gossans, the latter being the main gold mineralized bodies prospected in the Águas Claras area. The mineralogy of the entire profile is basically represented by quartz, kaolinite and iron oxides-hydroxides, in different proportions. Accessory minerals such as tourmaline, wolframite, cassiterite and muscovites are frequently found, occurring in varying amounts, practically in all samples. The mineralogical composition found in the various materials analyzed is quite simple in terms of the variety of minerals, but the proportions of the mineralogical phases vary greatly, even within samples from the same horizon. The minerals that represent the greatest distribution among the samples are quartz and hematite. The first occurs abundantly in the oxisol, decreasing significantly in the lateritic crust samples with almost total disappearance in the gossans samples, while the behavior of the hematite is the opposite. The geochemical associations obtained through the multi-elementary analyses: Oxisols: 1) As – Cu – B – Au – W - (Mn) - (Pb); 2) Cr – V – Ga – Mo – Ni – Zn; Colluvium: 1) As – Y – Cu – Mn – Pb – Mo; 2) Au – W – B – F; Lateritic crust: 1) As – W – Au – B – F – Sn; 2) Cu – Ni – Pb – Zn – Sc. The most characteristic geochemical association in all horizons is that represented by Au-B-W-As, possibly with Sn-Cu-F, which must reflect the geochemical signature of the Au-sulfide primary mineralizations, in addition to the influence of the host sediments in addition to the granitic intrusions. Other associations or pairs of correlations involving Cr-V-Ga-Mo-Zn are related to the ease of these elements being incorporated into the structure of iron oxides and hydroxides, abundant in all studied horizons. The gold particles found in the various horizons, have quite varied morphology and purity, which may indicate the presence of several stages of mobilization of this metal in the supergenic environment. As for the trace elements, there are strong anomalies of W, Sn and B, with the minerals responsible for the high levels, respectively, wolframite, cassiterite and tourmaline, the latter belonging to the compositional field of dravita-schorlite, rich in iron , getting very close to the field of ferridravites. Within the above, it can be said that despite the mineralogical simplicity, the concentration of trace elements is quite heterogeneous, but with characteristic signatures that remain in different horizons and that allow delineating the mineralized supergenic bodies and inferring the composition of the primary bodies. The understanding of the dispersion and the characterization of these geochemical signatures prove to be of great importance in geochemical prospecting, in the exploration of other bodies of similar nature in the region.
Acesso aberto (Open Access)
Avaliação ambiental das vias de drenagem da região metropolitana de Belém (PA) quanto à distribuição dos elementos Ca, Cd, Cr, Cu, Fe, Hg, K, Mg, Mn, Na, Ni, Pb e Zn
(Universidade Federal do Pará, 1991-01-07) MAZZEO, Tereza Elizabete; RAMOS, José Francisco da Fonseca; http://lattes.cnpq.br/8189651755374537
The investigation of the concentrations of heavy metals in the seven main drainage routes of the city of Belém, with a view to the environmental issue, is the central content of this work. The introductory chapters focus on the geology, geomorphology, soils, climate, vegetation and hydrology of the city of Belém, characterizing the natural conditions of the environment in the studied drainages. From the methodological point of view, the work has two phases: the first consists of the recognition, location and determination of metals (Ca, Na, K, Mg, Fe, Cr, Zn, Cu, Cd, Pb, Ni and Mn) and their main sources, natural or anthropogenic, or both; the second, in detailing the distribution and chemical behavior of each metal in the Tucunduba stream, which has a higher concentration of these elements. The Tucunduba stream presents, in addition to the sources of metals common to all other drainages, such as domestic sewage, rainwater discharge and the influence of estuarine tides, the effluent from a leather treatment industry, thus showing anomalous values for the chromium element. The investigation of the physical-chemical parameters of the waters of the drainage ways studied, aims to characterize and identify the behavior of the metallic compounds formed, emphasizing the seasonal variation - function of the rainfall intensity - and the action of the outgoing tides. The Tucunduba stream is the only one to be considered polluted by metals - due to the high concentration of chromium found in its waters and sediments - compared to polluted rivers and lakes in Brazil, Europe and the United States. Despite the small number of samples from each drainage and the great variation in the results, some linear correlations were observed between the concentrations of metals, among themselves and with the physicochemical parameters, which characterize the intense influence of the tides of the Guajará Bay and the Guamá River in the drainages. These correlations also show the existence of large amounts of surfactants derived from synthetic soaps and detergents.
Acesso aberto (Open Access)
Avaliação da contaminação por metais pesados em sedimentos por atividades de estaleiros na Baia do Guajará e no canal do Rio Maguari
(Universidade Federal do Pará, 2021-12-17) GUIMARÃES, Robledo Hideki Ebata; WALLNER-KERSANACH, Mônica; http://lattes.cnpq.br/7960214506412584; CORRÊA, José Augusto Martins; http://lattes.cnpq.br/6527800269860568
Antifouling paints applied on ships contain high concentrations of metals in their composition, mainly copper and zinc, with concentrations above 50% and 20%, respectively. Despite being essential elements for living beings, in high concentrations it causes problems in cell growth and reproduction of organisms. In the city of Belém, State of Pará, a significant amount of industrial and domestic effluents is released into the Bay of Guajará, one of which is related to activities in shipyards. Previous studies have shown evidence of metal contamination in the sediments in the edge of Belém estuary, however, no work has highlighted contamination from shipyards. Therefore, the objective of this work is to evaluate sediment contamination by activities in shipyards and abandonment of vessels in the edge of Belém city. The three samples of sediments were collected in 5 shipyards in Belém, two of which were collected in the less rainy period (September 2017 and November 2019) and one in the rainy season in May 2018. The sediment was collected up to 10 cm deep, and samples of paint fragments and fragments of the hulls of abandoned vessels were collected. The in situ pH of the interstitial sediment water was measured. In the laboratory, the sediment samples were placed in an oven at 60°C to dry, disaggregated and then sieved (< 63μm). The samples of paint fragments and the hulls of abandoned boats were washed with deionized water and dried in an oven at 60°C, macerated, mixed with the sprayed white area and reserved. A sample of the commercial paint most commonly used in shipyards was placed on a cellulose nitrate membrane in a hood, after which part of the sample was removed and macerated. An aliquot of the sediment samples from each shipyard was used for particle size analysis, using a laser particle analyzer. The mineralogical composition of the sediment samples was determined by X-ray diffraction, powder method. The clay minerals were determined by X-ray diffraction, following Stokes' Law and according to the methodology proposed by Moore & Reynolds Jr (2002). For the determination of total organic carbon, a TOC - VCPH analyzer with a combustion detector was used. To determine the concentrations of Cu, Zn, Pb, Ni, Cr, Ba, V, Li, Fe and Al contained in sediment, commercial paint, paint fragments and hull fragments of abandoned ships, the samples were subjected to chemical extraction with aqua regia and determined through Optical Emission Spectrometry with Inductively Coupled Plasma (ICP-OES). For statistical treatment of the data, Spearman's correlation was applied to determine the relationship between the parameters, and the Principal Component Analysis test to determine the relationship of metals with shipyards, control station and diffuse anthropogenic source station. The Wilcoxon test was also applied to verify if there were significant differences in the metal concentrations of the sediments collected in front of the shipyard with the sediments collected that were in contact with the abandoned vessel. To assess the level of contamination by metals, the geoaccumulation index proposed by Muller (1969) was applied. The sediment granulometry of the Belem shore presents a higher proportion of sand and silt. The sediments are composed of muscovite, illite, kaolinite, quartz and plagioclase. The clay minerals identified were: smectite, kaolinite, illite and quartz. The pH values of the interstitial water of the sediment samples from Baía do Guajará and Furo do Maguari were around 5.2 – 6.7. The total organic carbon of the sediment was around 0.6% to 2.2%. The commercial paint analyzed presented the following concentrations: Fe (21.2%), Cu (18,497 mg kg-1), Zn (16,589 mg kg-1) and Al (1.59%). The highest concentrations found in the composition of paint fragments and in the fragments of the hulls of abandoned vessels were: Fe (69.2 %), Ba (29,583 mg kg-1), Zn (9,350 mg kg-1), Pb (1,406 mg kg-1), Cu (697 mg kg-1) and Cr (548.7 mg kg-1). This result revealed that abandonment of vessels is the biggest source of contamination in shipyard areas in the city of Belém. According to the Sediment Quality Guidelines for Metals in Freshwater Ecosystems by Buchman (2008), only the average concentration of Cu, with 41.0 mg kg-1, in the sediment reached values above the Threshold Effects Level for the amphipod, Hyallela azteca (28.0 mg kg-1) in the ABSS shipyard. The other shipyards had copper averages ranging between 13.3 – 28.3 mg kg-1. The other metals had mean concentrations always below the Threshold Effects Level value. Spatially, the sediments that were collected in front of the ABSS shipyard for most metals had higher concentrations compared to the sediments that were in contact with the hull of the abandoned ship, of this shipyard. However, the sediments that were collected in front of the MS shipyard in general had lower concentrations compared to the sediments that were in direct contact with the abandoned vessel. Those that presented with concentrations of Cu (39.0 mg kg-1), Zn (120.0 mg kg-1) and Cr (32.0 mg kg-1) that exceed the value of Threshold Effects Level for the amphipod. However, the Wilcoxon Rank statistical test did not attest significant differences in the sediment collected in front of the shipyards with the sediment that was in contact with the abandoned vessels. The main elements that make up the antifouling paints: Cu, Zn had a strong positive correlation (r = 0.80; p<0.05). The Principal Component Analysis confirmed contamination by the metals Cu, Zn, Pb, Ni, Li, Fe and Al and has a stronger relationship with shipyard activities and ship abandonment than with diffuse geogenic or anthropogenic sources The geoaccumulation index classified the sediments close to the IS and ABSS shipyards as moderately polluted for copper with indices of 2.0 and 2.5, respectively. The other metals Zn, Ba, Fe and Al in the studied shipyards show an anthropogenic contribution by activities in shipyards and abandonment of vessels, classifying one or more shipyards as being in a situation close to a polluted environment, for one or more studied metals, with geoaccumulation index close to 2. The results can support additional studies of metal contamination through activities in shipyards and abandonment of vessels, and it can assist in the application of waste management in shipyards and ship cemeteries around the world.
Acesso aberto (Open Access)
Avaliação da influência dos cátions Na+, Ca2+ e Mg2+ na desativação de Ca, Mg-Bentonitas
(Universidade Federal do Pará, 2015-04-28) CARMO, Andre Luiz Vilaça do; ANGÉLICA, Rômulo Simões; http://lattes.cnpq.br/7501959623721607
In Brazil there is no occurrence of sodium bentonite, because of that, companies that explore this mineral raw material using a denominated sodium activation process, which is the exchange of cations in the interlayer space by Na+. Through this process, the bentonite present considerable improvements in their properties rheologies. However, after some time, these properties decline, which has been called deactivation. Thus, the objective of this study was to evaluate the influence of cations Na+, Mg 2+ and Ca2+ in the bentonite deactivation. For this, three bentonite considered calcic, from the state of Paraíba, and a magnesian, coming from the state of Maranhão, were studied in its natural form, activated and washed. The mineralogical phases of the samples were identified by X-ray Diffraction (XRD), chemical composition by Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and cations in the interlayer by Cation Exchange Capacity (CEC). The rheological properties’ study was carried out by swelling. The XRD patterns showed that the dioctahedral smectite is the dominant mineral phase. There was the improvement in swelling results of all bentonite after the sodium activation, as well as subsequent decrease in the swelling value over 95 days (deactivation). Only one of the bentonite remained activated. The swelling results of washed bentonite showed increased for approximately the first 35 days, with subsequent decrease. The chemical composition results showed that a small amount of Na+ is removed from the washed bentonite. Furthermore, these results indicate that not only Na+ influences the swelling, but also Ca2+ and Mg2+ cations.

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