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Dissertações em Geologia e Geoquímica (Mestrado) - PPGG/IG

URI Permanente para esta coleçãohttps://repositorio.ufpa.br/handle/2011/2604

O Mestrado Acadêmico pertence ao Programa de Pós-Graduação em Geologia e Geoquímica (PPGG) do Instituto de Geociências (IG) da Universidade Federal do Pará (UFPA).

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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 de molibdato em minerais de argila delaminados e amorfizados
(Universidade Federal do Pará, 2012-04-15) PEREIRA, Patricia Magalhães; LEMOS, Vanda Porpino; http://lattes.cnpq.br/1829861620854008
The search for efficient methodologies to control environmental pollution, as well as the development of technologies in the fields chemical, physical and biological have been widely discussed in order to produce efficient alternatives to improve the quality of life and control of chemical pollutants (organic or inorganic) that over the years are being dumped into the environment so as inconsequential by households and industries. Thus, it is important to know about the adsorptive behavior of metals in the soil, because high concentrations of metals produce adverse effects on the environment. Molybdenum is an essential element for biological functions of plants and animals, but in high concentrations in the body can lead to bone deformities, anemia, abnormal liver and lead to death.The possibility of interaction of organic-inorganic compounds (Humic Acid, Urea andH2SO4) in sediments "in nature” from the region of Acre, was investigated with the aim of evaluating the possibility of applying these materials in adsorption processes in molybdate aqueous solutions. The natural samples used in this study have a high content of clay minerals, mainly smectite, kaolinite and low content of primary minerals such as feldspar and quartz. All samples "in nature" were characterized by XRD, XRF, FTIR, SEM and pHH2O and pHKCl. The modification with inorganic acid concentrations (0.25, 0.5, 1 and 1.5mol.L-1), temperature and contact time are important parameters in the process of delamination of the clay minerals. As the use of organic compounds such as urea and humic acid were efficient in the amorphization. The study by XRD in the modified samples show a change in the structure when H2SO4 at the concentrations used, but this fact is only observed for 15Å peak, characteristic of smectite, all other peaks showed no significant change. The synthesis of organic compounds promoted the amorphization of the smectite peak reference. Thus, as the sediment naturally has clay (smectite, kaolinite), confirmed by XRD and the presence of iron, indicating a transition to the montmorillonite nontronite, and with isomorphous substitution of iron is expected to strong interaction between the adsorption molybdate fractions modified with respect to the natural. The introduction of H+ due to the modification process with sulfuric acid promoted the replacement of calcium ions in the structure confirmed by semi-quantitative analysis performed by EDS. SEM analysis indicated the presence in natural samples cluster morphology, this fact was not observed in the modified samples, which was observed delamination and amorphization. The equilibrium conditions in the adsorption process were investigated in which it is inserted, time of 2 h and the solution pH was measured before and after adsorption. The equilibrium datawere represented by theisotherm models Langmuir, Freundlich and Sips. The adsorption process had better performance in the concentrations for samples and S10H15 S10UH. The humic acid modified samples contained higher Qmáx =3.43, values regression fit to the model obtained indicate Freundlich efficient adsorption process, the modified samples effective adsorbed molybdate anion in comparison to natural sample.
Acesso aberto (Open Access)
Adsorção de nitrato em rejeito de caulim organofuncionalizado com uréia
(Universidade Federal do Pará, 2012-05-30) TAVARES, Laís Conceição; LEMOS, Vanda Porpino; http://lattes.cnpq.br/1829861620854008
Kaolin waste, generated in abundance by companies from Pará state, has caused to the environmental problems. In order to give input on the reuse of this waste was evaluated retention of nitrate ions on kaolin waste natural and modified with urea and studied the equilibrium of adsorption processes at solid-solution interfaces. The materials were characterized by X-ray diffraction and X-ray fluorescence (XRF and XRD, respectiely), IR spectroscopy (FTIR spectrum), scanning electron microscopy and estimated data of surface charge. Adsorption experiments of nitrate ions in the waste natural kaolin (CRJN) and modified with urea (CRJU) were performed without pH adjustment. H + concentrations were measured by direct potentiometry before and after the process of adsorption and equilibrium concentrations of nitrate were measured by ion chromatography. The results indicated: high purity kaolin waste; formation of kaolinite-urea complex confirmed by XRD reflection at 2  8,28o e d = 1.068 nm and the FTIR spectrum with the appearance of a broad band of low intensity, containing two discrete shoulder around 3500-3380 cm-1, corresponding to asymmetric and symmetric vibrations of the group-NH2 of urea-kaolinite, superimposed to the vibration of water. surface charges data, suggesting that the materials have a higher capacity to adsorb cations than anions, but depending on the concentration of H + and OH- on adsorbent, the hydroxyl surface can be protonated yielding positive charges that are reflected in the adsorption of anions, obtaining significant adsorbed nitrate, both in CRJN as CRJU (0,27-0,73 and from 0,18-0,70 3.5 mg g-1, respectively), the separation coefficient (RL) of from 0,28 to 0,828 change in free energy ΔG ° = -2,094 to + 0,445 kJ mol-1 for CRJN and ΔG° = -1,036 to + 1,32 kJ mol-1 for CRJN molecule. The data from RL indicated that the adsorption processes are less favorable in most points of the adsorption processes and based on the results of the free energy change (ΔG º) was showed low spontaneity to no spontaneity and adsorption processes are physical.
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)
Afinidades geoquímicas entre sedimentos (solos) e vegetação (gramíneas e cultivares), além de cabelo de ribeirinhos, ao longo das praias de rios da bacia do Juruá, no estado do Acre e sua importância ambiental
(Universidade Federal do Pará, 2005-06-10) RÊGO, José de Arimatéia Rodrigues do; COSTA, Marcondes Lima da; http://lattes.cnpq.br/1639498384851302
The State of the Acre is located in the southwestern extremity of the Brazilian Amazonia, in an area of 153.149 km2, with a low population density (3,66 inhabitants/km2). The studied area comprehends the basin of the Juruá river between the Feijó and Cruzeiro do Sul cities, including Tarauacá and Rodrigues Alves. In the basin the main rivers are: Juruá, Tarauacá, Envira, Muru and Moa. The same carry in sediments great amounts by traction and suspension from siltic- argillaceous rocks of the Solimões Formation and deposite in beaches formed along the rivers. In drought periods the beaches (point bars) are displayed in its meanders and benefit the riparian that use them to leisure and to short cycle agriculture. The beaches sometimes are used to cultivs of maize (Zea-Mays) and beans (Vigna unguiculata (1) Walp). These beaches also present a vegetation succession of canarana grass (Costus spicatus) and orvalho grass (Brachiaria decumbes). This study evaluates the high fertility of the beaches sediments (soils) and the geochemistry affinity between their sediments and the crops besides riparian hair and the environmental importance of this cycle. So the main rivers that constitute the Juruá basin, enclosing Feijó, Tarauacá, Cruzeiro do Sul and Rodrigues Alves cities were related. Nine stations were established along the rivers and samples of beach sediments, canarana grass leaves, orvalho grass leaves and seeds and beans leaves had been leaves were collected. Besides this, measurement of phisical-chemical parameters of the rivers waters were caried out. Human hair samples were collected in the cities. The sediments samples were analyzed by X-ray difraction (XRD) for mineral determination, are by chemical ICP-MS for characterization (major and trace elements). In attempt to verify the content of Major and Trace Elements, like Ca, Fe, K, Na, Ba, Zn, Mo, Co, Cr, Cu, Pb, Hg, As and Se and their sediment — (solil) — crops transference were camet the chemical compositions analyses were carried out with regal water plus MS-ICP and neutron activation. The studied beaches sediments in the cultivated areas excet the beach of Moa river are essentially fine-grained, ranging from fine sand to silt. And are formed by in decressent order quartz, feldspars clay minerals (smectite, illte and kaolinite) and feldspars. Chemical are constitute binaimes by SiO, (68,0 98,9 % in weight), following by significaty lower values, of Fe>03 (0,13 to 4,37 %), MgO (0,02 to 1,03 %), KO (0,16 to 1,94 %), CaO (0,02 to 1,05 %) and Na,0 (0,02 to 1,03 %) and AlOs, are more concentrated in the sediments of Envira, Tarauacá and Juruá rivers. These values compened chemical with that one of the PAAS and, the Upper Crust, are slightly impoverished in Al, Fe, Mg, K, Ti as well as slightly in Ca and Na, diluted certainly for the high contents of SiO2. In general, the rivers waters of the Juruá basin are dark-colored, as white waters type, due to inorganic material in suspension (suspensates) in high concentration. The criterion of suspensates and phisical-chemical parameters (pH, DO, TDS, temperature, resistivity, electric conductivity and salinity) delimit three geographic zones (sub-basins): a) Envira-Tarauacá, b) Juruá and c) Moa rivers. The first one presents the highest values of all the analyze phisical-chemical parameters, except resistivity, and the area coincides with the more fertile land area State of the Acre. Among the studied vegetables the canarana grass leaves revealed are richerest in K, S, Ca, Mg, P than orvalho grass leaves. Canarana and orvalho grass present chemical similarity in relation to K, P, S, Mg and Ca elements. Only canarana grass, collected in the sediments of the Juruá river tends to become richer in Ca and S. The chemical elements transference sediment (soil)-vegetable presents an absorption for vegetal of the K>P>Ca>P. This order presents the major values for vegetables collected in the sediments of Envira river, emphisizing the importance of Envira river with greater transference potential of macronutrients and being a probable pointer of its superior fertility in relation to the other rivers of Juruá basin. In the sediment-crop-human chain the cycle of Hg shows that in the beach sediments of the Juruá, Envira and Tarauacá rivers the average concentration of Hg (27 ppb) in the sediments below the background range (50 ppb) and in the plants is in according to normal considered range (< 500 ppb) for plants that grow in soils with low contents of Hg; the average contents of Hg in hair in Tarauacá, Cruzeiro do Sul, Rodrigues Alves and Feijó rivers is about 3992 ppb. The lower concentration (average 1680 ppb) was found in Feijó and the higher (6240 ppb) in Cruzeiro do Sul, being normal values and slightly impact indicators, not observed in the region. The slightly anomalous values of Hg in hair is not related to the crops, as well as to the sediments. For hunam other sources of Hg disponibilization must be evaluated as fish or domestic or wild animals meats. The beaches and abrupt declivities (banks) of the white water rivers of the central and western regions of Acre (Juruá basin) are really fertile, adequated to short cycle agriculture and its nutrients and other elements are completely assimilated by vegetables and crops. For the present study the chemistry of the sediments and crops, as well as of human hair, shows that the region does not present geochemistry anomaly of any considerable antropogenic impact.
Acesso aberto (Open Access)
Afinidades petrológicas e geocronologia U-Pb em zircão de ortognaisses do Complexo Gnáissico-Migmatítico Água Azul, Terreno Sapucaia, Província Carajás.
(Universidade Federal do Pará, 2024-10-09) PINTO, Eliziane de Souza; OLIVEIRA, Davis Carvalho de; http://lattes.cnpq.br/0294264745783506; https://orcid.org/0000-0001-7976-0472
The Água Azul do Norte area is part of the geological context of the Carajás Province, precisely in the Sapucaia Terrain, according to the recent tectonic compartmentalization proposals presented by the Granitoid Petrology Research Group (GPPG/UFPA). This region is formed by a mesoarchean orthognathic basement with TTG affinity (Água Azul GneissicMigmatitic Complex; 2.93 Ga) associated with late Mesoarchean intrusions with sanukitoid signatures (Água Azul and Água Limpa Granodiorites; 2.88-2.87 Ga), high-Ba-Sr sodic (Nova Canadá Granodiorite; 2.89-2.87 Ga) and high-K calc-alkaline (Boa Sorte Granite; 2.89- 2.85 Ga) signatures. The review of geological and petrographic data indicated that the TTG crust of Água Azul do Norte is compositionally heterogeneous and records strong evidence of progressive metamorphism and migmatization. Therefore, this work reclassifies this TTG basement as being formed by orthogneisses, which occasionally present variations to tonalitic to quartz dioritic compositions that resemble fragments of a more primitive, intensely deformed and gneissified crust. These varieties show compositional banding in an E-W direction, often disturbed by shear bands and drag folds. Considering the classification of migmatites, they have an orthognathic paleosome and leucosomes rich in Qz+Pl±Bt parallel to the banding (stromatic metatexite) and frequentely outlined by mafic aggregates (melanosome rich in biotite and hornblende). They form four compositional varieties: i) hornblende±biotite tonalitic orthogneiss (HBTnl), ii) clinopyroxene-hornblende tonalitic orthogneiss (CHTnl), iii) epidote-biotite orthogneiss quartz diorite (EBQzD) and iv) hornblende-biotite orthogneiss quartz diorite (HBQzD). They present a large proportion of mafic minerals (M'> 15%), especially biotite and hornblende, which can occur slightly stretched along the foliation plane. Plagioclase and secondary quartz are abundant and occur in the matrix or, in the case of plagioclase, as phenocrysts, while alkali-feldspar and primary quartz are practically insignificant. Whole rock geochemical analysis indicated that samples MED-120A (EBQzD) and MEP-53B (HBQzD) present moderately magnesian character, medium-K calcium-alkaline signature, relative depletion in K2O, MgO, Ba, Ni and Cr and enrichment in Na2O, Al2O3, TiO2, Fe2O3 and Zr, reflecting a certain affinity with traditional tonalite-trondhjemitic associations. The presence of many zircon crystals with igneous features preserved in these samples marks the crystallization age of the protolith at 3.06 Ga, suggesting that they are crustal fragments approximately 100 Ma older than the underlying crust (Água Azul Orthognathic Complex). MED-144 (HBTnl) exhibited a strongly magnesian character, high-K calcium-alkaline signature, high K2O/Na2O ratio and enrichment in MgO, Ba, Ni and Cr, very similar to the composition observed in sanukitoids. The U-Pb data obtained for this sample indicated a crystallization age of 2.92 Ga, similar to that observed in sanukitoids described in the Ourilândia do Norte region (Arraias Granodiorite). The other samples showed significant contents of compatible elements (e.g. Fe, Mg, Ni, Cr) and moderate contents of incompatible elements (e.g. K, Rb, Ba, Sr, Zr, Ti) and revealed an intermediate behavior between TTGs and granitoids enriched in Mg, as well as a strong affinity with the São Carlos Orthogneiss (2.93 Ga) described in the same terrain. Concordant U-Pb ages obtained for samples MED-95A (HBTnl) and EDC-28B (CHTnl) indicated acrystallization at 2.95-2.93 Ga contemporaneous with the emplacement of the Água Azul TTGs and the São Carlos Orthogneiss. The textural behavior of the quartz and mafic minerals indicates dynamic recrystallization mechanisms at intermediate to high temperatures (~500-650ºC), while the morphology observed in the migmatites (stromatic metatexitic and leucosomes with hydrated minerals) suggests that there was a low amount of melt produced and fluids participation in the partial melting process. Combined with the mineral paragenesis (Pl+Qz+Bt±Hbl±Ep), these factors point to a granitic protolith metamorphosed under amphibolite facies conditions, with the migmatization being strongly contemporaneous with the deformation and peak of the regional metamorphism described in the Carajás region (2.89 Ga; MED-95A).
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)
Alteração supergênica dos basaltos do Porto Franco-Grajaú-MA
(Universidade Federal do Pará, 1985-10-04) VAQUERA VARGAS, Antônio; OLIVEIRA, Nilson Pinto de
Acesso aberto (Open Access)
Alvo Borrachudo, Serra dos Carajás (PA): rochas ígneas ricas em magnetita e apatita com mineralizações de sulfetos associada
(Universidade Federal do Pará, 1996-05-25) FARIAS, Edielma dos Santos; VILLAS, Raimundo Netuno Nobre; http://lattes.cnpq.br/1406458719432983
Acesso aberto (Open Access)
Ambiente deposicional, composição mineralógica e estudo isotópico Pb-Pb das zonas sulfetadas do Alvo São Martim, Cinturão Araguaia, sul do Pará
(Universidade Federal do Pará, 2004-07-07) LIMA, Aderson David Pires de; VILLAS, Raimundo Netuno Nobre; http://lattes.cnpq.br/1406458719432983
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 mineralógica por difratometria de raios-X e método de análise de agrupamento (cluster analysis) como critério para individualização de horizontes bauxíticos
(Universidade Federal do Pará, 2017-03-08) OLIVEIRA, Kelly Silva; ANGÉLICA, Rômulo Simões; http://lattes.cnpq.br/7501959623721607
The formation of wide profile of alteration like as bauxitic deposits on Amazon during Cenozoic period is resultant of intense intemperism caused by seasonal climate, elevated temperature and humidity that are characteristics this region. The bauxitic Province of Paragominas, localized in the east portion the state Pará and west portion of Maranhão, occupies 50,000 km2 approximately forming the largest group of bauxite of Brazil. This work was used X-ray diffractometry, a technique that requires little analysis time, minimum pretreatment steps and small sample amounts, associated with cluster analysis for identify and group samples of same horizon of bauxitic profile of the mine Miltonia 3, Paragominas-PA. The results obtain were correlated with chemical analysis, frequently used for quality control and processing of bauxites. The samples used in this work and your chemical analysis were made available for company Norsk Hydro. The mineralogical types of ore were initially defined through clusters analysis of the XRD patterns of two sections (HIJ-229 e HIJ-231) from polling mesh, with 23 holes each section, and with 375 samples analyzed in all. Based on peak position and intensity of the pattern XRD was possible discern the bauxitics horizons. Due the mineralogic similarity this horizon, the differences found in this group refer principals proportions of minerals constituents: Gibbsite, kaolinite, goethite, hematite, and, more rarely, quartz and anatase. Thought clusters analyses was possible to separate by group a set of similar samples, besides facilitate the analysis of many samples quickly and with efficient results. It was possible yet observe a good correlation of the clusters with the lithotypes identified by the company Norsk Hydro through the results of the chemical analysis. In this way, the analysis of clusters in diffractograms of samples of aluminum ore can be an efficient tool aiding in the protocols of processing of this material.
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)
Aspecto geoquímicos do material particulado da pluma estuarina do rio Amazonas: fatores que controlam as interações com as águas oceânicas
(Universidade Federal do Pará, 2000-02-10) PEREIRA, Simone Baía; EL-ROBRINI, Maâmar; http://lattes.cnpq.br/5707365981163429; https://orcid.org/0000-0001-7850-1217
The geochemical aspects addressed in this investigation are the determination of the chemical composition of the material in suspension in coastal waters under the influence of the mouth of the Amazon River, indicating the possible location of the source of suspended material, as well as the influences that it suffers along the continent transition -ocean. X-ray diffraction analysis indicated the predominance of kaolinite, illite and quartz clay minerals over the other identified inorganic components, observing the presence of chlorite, sometimes as a subordinate mineral in some samples, sometimes as a trace, and smectite in trace grades, which, like chlorite, is also present as a subordinate mineral. The centesimal mineralogical composition of the particulate material was estimated, associating the analytical results with X-ray diffraction data, using stoichiometric calculation, based on the scientific literature. The results obtained through the stoichiometric calculation confirm the tendency shown by the diffractograms. It is observed that the dominant clay minerals are kaolinite (maximum in 51.19%), associated with high levels of aluminum, distinguishing the dominance of this clay mineral in the sample in which this fact occurs, and illite (maximum in 42.43%) associated At high levels of potassium, when this clay mineral dominates the samples, the presence of iron and titanium colloids was also admitted. The content and nature of the organic matter associated with suspended sediments were evaluated, using elemental analysis for carbon, nitrogen and hydrogen, thermogram records and absorption spectra in the infrared region. In the sediments, organic compounds predominate (clay minerals, silica, iron colloids), with organic matter always having a content below 3.6%. Therefore, in interpreting the records of absorption spectra in the infrared region, the most intense bands are related to the dominant clay minerals in the material, that is, the illite and kaolinite mixture. Bands related to chemical bonds in clay minerals dominate in the infrared spectra. The clear and intense vibration band of the Si-O stretching, which extends from 1200 to 1000 cm-1, with its most significant developments around 1180 and 1034 cm-1, is well representative of structures of the illite and kaolinite types. And there is still a clear band, with weak folds around 950 to 915 cm-1, related to the Al-OH bond; bands around 790-800, 750-780, 640-690 cm-1; or in the range of 400 - 600 cm-1, the intense absorption bands recorded in the range of 4000 - 3400 cm-1, with their various developments, related to the bonds with hydroxyl, –OH, so common in clay minerals and an intense and average band recorded around 1640 cm-1 corresponding to the angular deformation of the HOH bond, a characteristic of constitutive water present in clay minerals. The infrared absorption spectra of humic and fulvic acids from different sources are similar but not identical. The (subtle) differences are the result of brief changes in their compositions. Perhaps the most interesting feature of the spectrum of humic acids is the appearance of intense and broad absorption bands related to the stretching vibrations of the C=O bond of several organic functional groups (carboxylic acids and their derivatives, aldehydes, ketones), in the range from 1709 to 1715 cm-1 and vibrations of aromatic compounds around 1600 to 1613 cm-1. The bands recorded around 1698 to 1701 cm-1 and around 1400 cm-1 indicate the presence of carboxyl and carbonyl groups. The most interesting aspects of the recorded spectra concern the appearance of clear (but weak) absorption bands in the range of 2959-2885 cm-1, attributed to methylene groups –CH2- of hydrocarbons; and the presence of a weak (but clear) band around 1385 cm-1 referring to the carboxyl and/or carbonyl groups. Leading to the conclusion that it is humic material present in organic matter from leaching and drainage of typical Amazonian soils, such as podzolic and latosolic. Elementary organic carbon contents range from 1.27% to 2.05%, while nitrogen contents range from 0.03% to 0.13%. These contents produce high C/N ratios (minimum 12.7% and maximum 68.3%) of material rich in cellulose decomposition products of vegetable origin. The integration of data from the chemical analysis of suspended matter with physical-chemical parameters of coastal waters and the variation in phosphorus levels (minimum of 0.06% to maximum of 0.71%, expressed in P2O5), associated with salinity variation (minimum of 24.31‰ and maximum of 39.19‰), used as limiting parameters, defined the existence of three characteristic zones of origin of suspended material: one predominantly terrigenous, one transitional and one predominantly oceanic biogenic.
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)
Assinatura geoquímica de apatita de rochas sanukitoides do sudeste do cratón amazônico, Província Carajás.
(Universidade Federal do Pará, 2019-05-26) FONSECA, Camila Santos da; LAMARÃO, Claudio Nery; http://lattes.cnpq.br/6973820663339281
The Rio Maria Sanukitoid Suite, included in the Rio Maria Domain, southern portion of the Carajás Province, is composed of granodiorites and associated mafic and intermediary rocks. It has large exposures in the north of Redenção city, south of Rio Maria, east of Bannach and northeast of Xinguara, SE portion of the Amazonian Craton, being intrusive in greenstones of the Andorinhas Supergroup, Arco Verde Tonalite and Complex Caracol Tonalitic. Other granodioritic rocks correlated to the Rio Maria sanukitoids were described in the regions of Água Azul do Norte, Ourilândia do Norte, Serra do Inajá and Xingu region, all of them included in the Carajás Province. The Rio Maria Sanukitoids are metaluminous rocks, calcic-alkaline affinity and enriched with Mg, Cr and Ni in relation to other granodiorite rocks. They present primary epidote, zircon, allanite, titanite, apatite and magnetite as main accessory phases. U-Pb and Pb-Pb zircon dates defined crystallization ages of 2,87 Ga for these rocks. Apatite is a generally early mineral in the order of crystallization of granitoid rocks. Because of its properties, it can incorporate variable contents of REE and other trace elements, such as Na, K, Mn, F, Cl, Sr, Y, Pb, Ba, Th, U, V, and has been used as a good petrological and metallogenetic indicator of its host rock. The objective of this dissertation was the morphological and compositional study, by electron microprobe, of apatite crystals of granodioritic rocks from Rio Maria Sanukitoid Suite in Rio Maria, Ourilândia do Norte and Bannach regions, Rio Maria Domain, Carajás Province. For comparative purposes apatites of Leucogranodiorite with high Ba-Sr from Água Azul do Norte and of the Trondhjemite Mogno from Bannach region, both archaeans, have been studied. It was also compared to the apatites of the Seringa and Antônio Vicente paleoproterozoic type A granites, the first weakly oxidized and sterile, and the second, reduced and mineralized to Sn. The apatites of the Ourilândia do Norte sanukitoids have compositional zonations concentric to oscillatory more evident and complex, with well defined light-dark zones. On the other hand, the apatites of the Rio Maria and Bannach sanukitoids form more homogeneous crystals, with not evident or non-existent zones. The apatites of high Ba-Sr Leucogranodiorite and Mogno Trondhjemite are equally developed (> 150 μm), but with rare zoning restricted to the edges of some crystals. Inclusions of zircon are common only in apatites of Mogno Trondhjemite. In the Seringa granite, the apatites are comparatively smaller (<100 μm), subhedral to euhedral and with well defined zonations, while those of the Antônio Vicente granite are poorly developed (<30 μm), subrounded and free of compositional zonations. The main compositional variations among the apatite of the Rio Maria Domain, in addition to CaO, P2O5 and F, are in the highest content of LREE (La, Ce, Pr, Sm, Eu) found in the apatite of Ourilândia do Norte and Rio Maria in relation to those of Bannach, which show lower concentrations and sub-horizontal trend in the diagram (La + Ce + Pr + Sm) vs. (Gd + Yb + Y). This enrichment in REE is more evident in the diagram ΣREE + Y vs (La + Ce + Pr + Sm + Eu), where the studied apatite form an enrichment trend towards the Bannach - Rio Maria - Ourilândia do Norte sanukitoid. Based on this geochemical signature, similar and more enriched magmatic sources in LREE are suggested for the apatites of Ourilândia do Norte and Rio Maria. On the other hand, the apatites of Bannach sanukitoids presented higher and more variable concentrations of CaO, P2O5 and F and lower LREE, suggesting origin from a compositionally different and more LREE depleted magma. The apatites of the Mogno Trondhjemite and the leucogranodiorite high Ba-Sr are also more impoverished in LREE and tend to follow the apatite of the Bannach sanukitoides in the diagrams, but the apatite of the leucogranodiorites show greater enrichment in Sr. The Seringa granite has apatites more enriched in F and REE + Y when compared to the apatite of the archaean rocks, and they stand out in all the geochemical diagrams. This fact demonstrated that apatite compositions can also be used to record petrogenetic processes and to differentiate magmatic compositions that marked changes during the crustal evolution of a region, for example, distinguishing between Archaean and Paleoproterozoic granitoids, and are, therefore, useful in studies of provenance. Apatites of Antônio Vicente paleoproterozoic granite, mineralized in Sn, show high concentrations of F, Mn, Fe, Y and REE (except Eu), in comparison to other granitoids and can be used as a good metallogenetic indicator.
Acesso aberto (Open Access)
Assinatura isotópica de Pb em sedimentos da margem leste da Baía do Guajará (orla de Belém) e rio Maguari
(Universidade Federal do Pará, 2020-10-05) BARRA, Ingledir Suely Silva; LAFON, Jean Michel; http://lattes.cnpq.br/4507815620234645
Estuarine sediments provide a long-term record of the accumulation of trace metals from riverside, atmospheric and anthropogenic sources. The release of trace metals from point sources is largely controlled by the natural processes of physical and chemical weathering of rocks, in addition to anthropogenic disturbances that can occur on a large scale. In addition to diffuse anthropogenic sources, estuarine sediments can be enriched in trace metals by antifouling paints, with high contents of metals (Cu, Zn, Pb), which are applied to ship hulls and many submerged structures to prevent the growth of fouling organisms such as bacteria, macroalgae, mussels, bivalves, and invertebrates. Pb isotopic signatures are useful tools to investigate the sources and mobility of trace metals in estuarine systems and allow to distinguish between geogenic and anthropogenic source contributions. In recent years, several isotopic Pb studies for this purpose have been conducted in the hydrographic system of Belém. The aim of this work is the application of Pb isotope geochemistry in bottom sediments, suspended particulate matter (MPS), and fragments of vessels with antifouling paint of several shipyards in Guajará Bay and the Maguari River, in the metropolitan area of Belém-PA. It is intended to verify whether the paints used in the shipyards can be considered a point source of contamination by Pb. Bottom sediment samples were collected at 9 stations along the northern and southern waterfront of Belém, at the right margin of the Guajará Bay, and 3 on the Maguari River near shipyards, 6 samples of suspended particulate matter and 4 samples of vessel hull fragments. Samples of bottom sediments at the mouth of the Una Channel (3 samples) and Paracui River (1 sample) were also collected. Finally, a sample of bottom sediments was also sampled on Barra island, in the middle of Guajará Bay, as a reference to the geogenic background. Chemical analyzes of bioavailable Pb were carried out on the bottom sediment samples by inductively coupled plasma optical emission spectrometry (ICP-OES) and Pb isotopic analyzes on all samples by inductively coupled plasma mass spectrometry with magnetic sector and multiple collectors (ICP-MS). In the bottom sediment samples from the shipyards of the Belém waterfront and the Maguari River, important variations of Pb concentrations of the bioavailable fraction occur, from a value similar to the reference point (11 mg kg-1) up to contents of 25 mg kg-1. These variations suggest incipient processes of anthropic action. Even so, the levels are within the range of concentrations found so far and do not show evidence of a significant contribution of Pb linked to the proximity of the shipyards. The similar ranges of bioavailable Pb concentration between the various sectors studied (northern and southern sectors of the waterfront Belém and Maguari River) show that there is no clear pattern of distribution of Pb levels in the sectors studied. These concentrations were shown to be systematically lower than the reference values TEL (35 mg kg-1) and PEL (91.3 mg kg-1), thus indicating that Pb is not causing harmful effects to biota in these areas of the Guajará Bay system. In the northern sector of the waterfront Belém and along the Maguari River, the variations in 206Pb/207Pb isotopic ratios are within the range of the Barra island reference point and the values considered geogenic in previous works (1.189 – 1.197). Only the point identified as “vessel graveyard” presented a lower ratio (206Pb/207Pb= 1.183) and may indicate an increase in Pb anthropogenic contribution due to the deterioration of abandoned vessels and the working shipyard. In the southern sector of the Belém shore, practically all the sediments from the shipyards and the mouth of the Una canal presented lower 206Pb/207Pb isotopic ratios (1.163 and 1.178), indicating an anthropogenic contribution. This diffuse anthropogenic contribution is apparently related to the Una channel and also to the greater concentration of shipyards and other possible sources of metals. In addition, the comparison of the Pb isotopic composition of the sediments at the mouth of the drainage channels in the northern and southern sectors of the Belém waterfront suggests the existence of a relationship between anthropogenic contribution and the size of the drainage basins, population density, and urban activities. No correlation was found between the 206Pb/207Pb isotopic ratios of the bottom sediments and corresponding MPS, however, all points fit a trend line, confirming the mixture between two different sources of Pb for both sediments and suspended material. The isotopic signatures of the hull + paint fragments are positioned along the same trend line established between a geogenic end-member and an anthropogenic end-member (aerosols), for the hydrographic system of Belém, making it impossible to identify a specific anthropogenic source of Pb from the shipyards. The comparison of these signatures of the fragments with the bottom sediments of the shipyards indicates that this possible anthropogenic source enters as one of the subordinate components of the diffuse anthropogenic contribution of Guajará Bay. Finally, based on the data from this study and the works already developed in the hydrographic system of Belém, it is proposed to extend the range of 206Pb/207Pb ratio of the geogenic Pb to 1.189 – 1.204 for the hydrographic system of Belém, as a whole.