Navegando por Assunto "Sedimentos de fundo"

Agora exibindo 1 - 7 de 7

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.
Acesso aberto (Open Access)
Avaliação da qualidade dos sedimentos de fundo do Rio Murucupi, Barcarena-PA.
(Universidade Federal do Pará, 2011-07-15) REIS, Rafael Melo dos; CORRÊA, José Augusto Martins; http://lattes.cnpq.br/6527800269860568
The development of industrial and urban centres in Barcarena often causes substantial changes in the bodies of water of surrounding areas, primarily in water quality, as a result of inputs of potentially toxic trace elements, as shown the studies of Pereira et. al. (2007), Víglio (2008), Porto (2009) e Pereira (2009). In addition, major environmental accidents has been recorded, mainly related to the disruption and overflow of accumulation dams of industrial waste. In this context, in 2003 and 2009, the river basin Murucupi, wich incudes the urban centres of Vila dos Cabanos and Laranjal, was contaminated by rejects from the beneficiation process bauxite, known as “red mud”. The objetive of this study was to assess preliminarily the bed sediment quality of Murucupi river and distribution of major elements (Al2O3, Fe2O3, TiO2 e Na2O) and trace (Zr, V, Cr, Th, Hf, Ga, La, Sc, Pb, Nb, As, Cd, Cu, Hg, Ni e Zn), enriched in red mud, along the river. For this, triplicate cores were collected with 50 cm deep in bed sediments, in seven ponits along the Murucupí river, in the 5,3 km stretch between the access bridge to the Vila dos Cabanos (M-1 point) and the river mouth (M-7 point). Each sediment core collected in the field was subdivided into five depth intervals in the laboratory: 0-10 cm (A interval), 10-20 cm (B interval), 20-30 cm (C interval), 30-40 cm (D interval) e 40-50 cm (E interval). The triplicate samples from each respective depth interval were then thoroughly homogenised, and later, size, mineralogical and chemical analyses were performed in each sample. The results showed that the sediments are primarily composed of quartz, mica group of minerals, priority muscovite, and albite, in addition to clay – kaolinite, smectite and ilite. The superficial concentrations of the major elements P2O5 and S, and of the trace elements V, Cr, Ga, Pb, Hg and Zn, were higher in M-1 point with a strong decrease toward to mouth, indicating contamination by discharges of urban runoff and domestic sewage from the Vila dos Cabanos and Laranjal. In other hand, the superficial concentrations of S, As and Pb, were high in M-7 point, indicating contributions of these elements from the Arrozal stream, possibily arising from the port of Barcarena and surrounding areas, brought to the mouth of the Murucupi river through tidal movements. The concentrations of these trace elements into beb sediments were much smaller than values measured by Braga (2007) in red mud. This fact is associated to methodological differences used na chemical analysis and to thickness of the sample. However, the statistical correlations performed among Al and Cr, V, Ga and Th, and among Mg, K and Hf, La, Sc and Zr, as well as among Mg, K and the "silt + clay" particle size fraction over the depth, demonstrate that exist a "geochemical signature" of the events of contamination by red mud, recorded in A interval of sediment cores collected in the Murucupi river. The results obtained by the distribution of elements with depth showed that, in general, the major elements Al2O3, MgO and K2O are associated with “silt + clay” particle size fraction, and that the variations in the concentrations of the trace elements, mainly reflect environmental conditions more favorable for mobilization or persistence of these elements over the depth. With regard to the sediments quality, the concentrations mensured for each element were compared with sediment quality indices, known as Sediment Quality Guidelines – SQG, developed by Canada and adopted by Brazil through CONAMA resulution nº 344/2004, and with the indices “consensus-based”, developed by Macdonalds et al. (2000), and also, with reference values of background in the region. Some places, the bed sediments of Murucupi river showed concentrations above ISQG and below PEL for the following elements: 1) Cr in M-1 point, A (38,4 mg.Kg-1) and E (43,1 mg.Kg-1) intervals; 2) Ni in M-6 point, E (18,9 mg.Kg-1) interval, and in point B-1, A (18,6 mg.Kg-1), B (18,3 mg.Kg-1), C (18,4 mg.Kg-1) and E (18,3 mg.Kg-1) intervals; 3) As in M-1 point, C (5,9 mg.Kg-1) interval; and 4) Hg in M-1 point, E (0,199 mg.Kg-1) interval, and in M-2 point, E (0,233 mg.Kg-1) interval. These results indicating that, in these sites, adverses effects to benthic organisms may occur due the high concentrations of Cr, Ni, As and Hg in beb sediments, wich entails additional studies of bioavailability in sediments and toxicity in benthic organisms. Highlights that the elements Pb, Cu, Ni, As, Hg and Zn are enriched over the referece value of regional background at all points sampled in Murucupi river, being that the Cr enrichment also presented in relation to the concentration mensured by Nascimento (2007) in bed sediments of Guamá river. and Pb enrichment only at specific points, related to the hydrodynamics of the river. The results obtained for the Ni raised two hypotheses: 1) in the basins of the Murucupi river and of the reference stream, may exist difusal or eventual sources of contamination for the Ni; or 2) the Ni can be naturally enriched in the region, since the statistical correlations among Mg and Ni in the sediment cores of Murucupi river were good or excellent in nearly all depth intervals. In general, the results obtained showed that the contamination in sediments of Murucupi river is much more associated with difusal sources of pollution, probably from urban runoff and discarges of domestic sewage, than with the environmental accidents involving red mud.
Acesso aberto (Open Access)
Caracterização da assinatura isotópica de Pb atual e da concentração de metais pesados em sedimentos de fundo da foz do rio Guamá e da Baía do Guajará (Belém - Pará)
(Universidade Federal do Pará, 2007-11-09) NASCIMENTO, Suziane Magalhães do; LAFON, Jean Michel; http://lattes.cnpq.br/4507815620234645
The city of Belem launches a significant amount of domestic pollutants in natura and industrial effluents in the Guama river and the Guajara bay. Previous studies suggest that the bottom sediments deposited in the edges of the river and the bay have its chemical composition influenced by these anthropogenic inputs. The aim of this work is to characterize the Pb isotopic signature, associated to the study of the distribution of the concentration of Pb and other heavy metals (Cu, Cr and Ni) in bottom sediments from the hydrographic system of Belem (Guama river and Guajara bay), in order to evaluate the regional natural variations and to evidence possible anthropogenic contributions from the industrial and urban activities of the city of Belem. Thirty three georeferenced samples of bottom sediments from the Guama river and from the Guajara bay were collected, using a Petersen grab, with capacity to sample the first 10 cm of muddy sediments. Fourteen samples came from the left edge of the Guama river, including the Cumbu and Great islands, until it flow into the bay and nine samples from the right edge, at the city riverside. Nine samples of bottom sediments were also collected from the Guajara bay, beside eight samples from the islands (Jaguar, Jutuba, Jararaca and Mirin) and one from the riverside of Belem for the determination of heavy metal contents and Pb isotopic composition. At the laboratory, samples were dried in an oven (50°C), disaggregated in a agate mortar and sieved down to 63μm, for the separation of the fine fraction (silt + clay). The mineralogical composition of the fine fraction was determined by X-rays diffraction. The total and partial heavy metals concentrations were determined, respectively, by ICP-MS at commercial laboratory (Acme Ltda), and by ICP-OES at the Toxicological Laboratory of the Instituto Evandro Chagas, Belem. The determination of the Pb isotopic compositions was carried out on samples previously leached using HNO3 at the Para-Iso Laboratory of the Instituto de Geociencas - UFPA, and using a mixture HNO3 + HCl at the Geochronological Laboratory of the Centro de Pesquisas Geocronologicas - USP. The Pb separation and purification were carried out by ionic exchange chromatography. The Pb isotopic compositions have been determined by TIMS on a monocollector mass spectrometer VG Isomass 54E with, at the laboratory of UFPA and on a multicollector mass spectrometer VG354 at the laboratory of the USP. The results indicate that the mineralogical composition of the fine fraction of the sediments includes smectite, illite and Kaolinite. Chemical analyses of heavy metals furnished the following total and partial contents for the samples from the Guama river right edge: PbTotal (11-23 mg.Kg-1); PbPartial (9-18 mg.Kg-1); 10 CrTotal (26-69 mg.kg-1); CrPartial (11-23 mg.kg-1); NiTotal (7-29 mg.Kg-1); NiPartial (6-26 mg.Kg-1); CuTotal (7-23 mg.Kg-1); CuPartial (6-17 mg.Kg-1). For the samples from the left edge of the river, the following total and partial concentrations were obtained: PbTotal (16-20 mg.Kg-1), Pbpartial (13–19 mg.Kg-1); CrTotal (34-56 mg.kg-1), Crpartial (16-26 mg.kg-1); NiTotal (12-21 mg.Kg-1), Nipartial (12-16 mg.Kg-1), Cutotal (9-14 mg.Kg-1) and Cupartial (7-12 mg.Kg-1). The sediments from both edges of the Guama river similarly display a slight decrease of heavy metal contents downstream, in the direction of the bay. However, the sediments at south of the left edge islands display an increase of contents in the same direction. Variation in the dynamic of aquatic system of the Guama river by combined effect of currents and tides would probably account for such an opposite behavior. For the sediments from the right edge, significant variations of the metals contents were locally identified and are considered to be due to the confluence of the Aura tributary, which provokes local disturbs in the hydrodynamic of Guama river as well as a redistribution of the metals along the right edge of the river at a local scale. Physical-chemical conditions of the Aura water are probably modified by the effects of the Belem waste deposit, located on the edge of the river, by increasing of the metals solubility that may account for lower heavy metal contents of the bottom sediments from the Aura river up to the confluence with the Guama river. Consequently, the Aura river will not provide any significant input of heavy metals in the Guama river. Correlation diagrams display a good correlation between heavy metals and the organic matter and excellent correlations with Al, Mg and the Fe (r = 0.95-0.99) for the samples of the right edge of the Guama river, indicating that the heavy metals are associated to the organic matter, adsorbed by the clay-minerals (smectite, illite and Kaolinite) and, probably, associated to iron oxy-hydroxides, though they have not identified. Samples of the left edge did not provide any correlation of Pb and Cr with organic matter (r = 0.24 and 0.40), however excellent correlations were identified with Al and Fe (r = 0.94-0.97). Cu and Ni are poorly correlated with organic matter (r = 0.59 and 0.72) while the correlations with Al, Mg and Fe are good (r = 0.74-0.89). Therefore, clayminerals and, possibly, iron oxy-hydroxides prevail for heavy metals contents. The sediments of both edges of the Guama river have, respectively, total concentrations of Pb (23 and 20 mg Kg-1) and Cu (23 and 14 mg Kg-1) lower than the 35 mg Kg-1 (Pb) e 36 mg Kg-1 (Cr) values of TEL (Threshold effect level), established by the NOAA-EPA as a guide of quality of sediments and that defines the level below of which adverse biological effects will rarely occur. Then, sediments of the Guama river, even so they are in contact with domestic pollutants, do not represent any 11 risk, at the moment, for the aquatic ecosystem, at least regarding to Pb and Cu. The total concentrations of Cr (69 and 53 mg Kg-1) and Ni (26 and 18 mg kg-1), for the sediments of the right and left edges, respectively, are higher than or equal to the respective TEL values of 37 and 18 mg kg-1 for these metals and may constitute a risk for aquatic organisms of the Guama river. However, such Cr and Ni concentrations come probably from natural sources without any significant anthropic influences. The homogeneous isotopic signature of the sediments of the Guama river, together with the low Pb concentrations indicate a geogenic origin for this metal and allow to establish a value for the regional "background" of Pb concentration around 18-23 mg Kg-1. They also allow considering an isotopic signature of 1.200-1.194 for the 206Pb/207Pb ratios of Pb from natural sources, reinforcing the values previously proposed by Moura et al. (2004). The lower contents of Pb found in some samples from the right edge of the Guama river (11-13 mg Kg-1), associated to slightly anthropogenic isotopic signature (1.186 < 206Pb/207Pb < 1.193) are interpreted as a result of the influence of the Aura tributary on the sediments of the Guama river. The significant increase of Pb contents in the stream sediments of the Guajara bay is an indicator of possible future biological risks in the hydrographic system of Belem. The well established negative correlation between Pb concentrations (28-46 mg Kg-1) and 206Pb/207Pb isotopic ratios (1.172 < 206Pb/207Pb < 1.188), discards the possibility that the increase of Pb contents in the Guajara bay to be of geogenic origin and that the difference in concentration with the Guama river to be resulted only of distinct hydrodynamic processes.
Acesso aberto (Open Access)
Dinâmica da distribuição dos poluentes metálicos e orgânicos nos sedimentos de fundo dos canais de drenagem de Belém, Pa
(Universidade Federal do Pará, 1995-10-17) NASCIMENTO, Fernanda Souza do; FENZL, Norbert; http://lattes.cnpq.br/6834981018643186
Acesso aberto (Open Access)
Distribuição de metais pesados e hidrocarbonetos poliaromáticos em sedimentos de fundo dos rios Magdalena e Bogotá (Colômbia).
(Universidade Federal do Pará, 1997-09-08) PIRATOBA MORALES, Gundisalvo; FENZL, Norbert; http://lattes.cnpq.br/6834981018643186
Acesso aberto (Open Access)
Distribuição de metais pesados e isótopos de Pb em sedimentos de fundo do rio Murucupi-Barcarena-Pará
(Universidade Federal do Pará, 2013-08-29) OLIVEIRA, Diomar Cavalcante; LAFON, Jean Michel; http://lattes.cnpq.br/4507815620234645
The preoccupation with environmental contamination by trace metals by urban and industrial activities has led to studies with the purpose of measuring the impacts and incorporation of these substances on aquatic biota. This study aimed to identify by determining the levels of trace metals and Pb isotopic signatures a possible involvement of effluents coming from the urban areas and industrial wastes as sources of pollution of the Murucupi river, Barcarena region, Pará. It is intended to point out the potential of Pb isotopic signatures to detect future impacts of anthropogenic contamination with trace metals. In addition, reference values of natural metal concentrations and Pb isotopic composition were identified for this sector of the Pará river estuary system values. Eighteen samples were collected from the bottom sediment surface along rivers Murucupi (8 samples), Arrozal Channel (6 samples) and Pará river (4 samples) and two drill cores in the Murucupi river. Surface samples and sediment cores were collected with Van Veen dredge type and Russian Peat Borer, respectively. A granulometric analysis was performed with laser granulometer to quantify the percentage of sand, silt and clay. The mineralogical composition was determined by X-ray diffraction. The partial and total concentrations of the metals and Lead isotopic compositions were determined by ICP-MS. The organic matter contents were determined by volumetric redox by the Walkley Black method. Granulometric analyses showed that there was a predominance of silt over sand and clay. Mineralogical analyses performed on the total sample and in the clay fraction showed the presence of quartz, albite muscovite and clay minerals smectite, illite and kaolinite. In all three drainage study, the results indicate that the levels of Pb, Cu, Zn and Ni did not show significant differences and when exist, they may be related to natural variations in the sediment. The correlation matrices indicate that the contents of trace metals are not controlled by the organic matter and that these metals are predominantly associated with structures of clay minerals in Pará river and Arrozal Channel sediments and oxy-hydroxides of Fe and Mn in Murucupi river sediments, respectively. High correlations between the trace metals indicate that the concentrations of metals in the sediments are governed by similar chemical processes in the three drainages, excepting for Pb in the Murucupi river, which is not correlated with others metals and may have been introduced into the environment by different processes. Most of the enrichment factors, using the Pará river sediments as reference value, showed values lower than 1, indicating no evidence of anthropic influence on the trace metals concentrations. Sediments from Arrozal Channel displayed contents of trace metals slightly lower than those of Murucupi river. However, the similarity of their EF values point to natural geochemical variations. The levels of Pb, Cr, Cu, Zn and Ni were lower than TEL reference value for all the trace metals studied. Therefore the sediments of the Murucupi river and Arrozal Channel, although in contact with domestic sewage, do not represent, at the moment, no risk to aquatic organisms. The bottom sediments of Pará river exhibit a homogeneous isotopic signature (206Pb/207Pbmean = 1.204 ± 0.001), considered as geogenic, establishing a background value of 206Pb/207Pb isotopic ratio for the area. Lower values found in the Murucupi river (206Pb/207Pbmean = 1.186 ± 0.003) and Arrozal Channel (206Pb/207Pbmean = 1.193 ± 0.002) are interpreted as reflecting the influence of effluents from the urban areas (Vila dos Cabanos and Laranjal) and from Barcarena river, respectively. Through 206Pb/207Pb vs. 206Pb/204Pb and 208Pb/206Pb vs. 206Pb/207Pbdiagrams, it is possible to discard a contribution of red mud tailings as a source of pollution of the Murucupi river. The decrease in 206Pb/207Pb isotopic ratios from bottom to top in sediments of the Murucupi river corroborate the existence of a recent Pb anthropogenic contribution to the sediments in this river.
Acesso aberto (Open Access)
Geoquímica elemental e isotópica Pb-Sr-Nd dos sedimentos de fundo do sistema estuarino de Belém e do litoral paraense
(Universidade Federal do Pará, 2016-12-19) OLIVEIRA, Elma Costa; CORRÊA, José Augusto Martins; http://lattes.cnpq.br/6527800269860568; LAFON, Jean Michel; http://lattes.cnpq.br/4507815620234645
In recent years, urban growth has occurred in a disorga¬nized manner in the metropolitan area of Belém, State of Pará, and this is reflected directly in the quality of water and sediments of the Guajará Bay, the main hydrological element of the estuarine system of Belém. This study aimed to conduct an elemental and isotopic geochemical research on bottom sediments from the western margin of Guajará Bay and Carnapijó river to understand the geographical and historical variations of heavy metals (Cu, Cr, Ni, Pb and Zn) contents and isotopic signature of Pb, and to evaluate the gradual environmental degradation in the hydrographic system of Belém. In addition, the provenance of the bottom sediments in three areas of the Amazon Coastal Zone (mouth of the Amazon River, Marajoara Gulf and northeastern coast of Pará) was investigated by elemental and Sr-Nd-Pb isotopic geochemistry. Sediments from the western margin of the Guajará Bay and from the Carnapijó River display mineralogical homogeneity and their sand to silty sand textural composition reflects very high hydrodynamic conditions. 210Pb dating furnished a rate around 0.7 cm.year-1 for the sedimentation at the western margin of Guajará bay. The trace metal contents in the fine fraction indicate that there are no significant anthropogenic contribution for Cu, Cr, Ni and Zn in the sediments from these sectors of the hydrographic system of Belém. However, the Pb contents suggest a weak anthropic action for this metal. The concentrations of Cu, Cr, Ni, Pb and Zn in the exchangeable fraction below the Threshold Effect Level (TEL) indicate that the metals do not offer risk to the local biota. Comparison between the studied sediments and those of the riverside of Belém point to a higher contribution in the latter from domestic sewage and industrial waste for Pb and Ni, followed by Cr and virtually nonexistent for Cu and Zn. The study indicates that the sediments of the Carnapijó River are suitable for use as background of the estuarine system of Belém in future geochemical studies. Isotopic signatures of sediments from the western margin of Guajará Bay confirm an anthropogenic contribu¬tion of Pb throughout the entire bay. The Pb accumulation process has become more efficient over the last 10 years, and this can be attributed to the rapid population growth of Belém city. Sediments in Carnapijó River are not affected by human activities, and the average concentration values (Pb = 19.6 ± 3.7 mg kg-1) and isotopic signatures (206Pb/207Pb = 1.196 ± 0.004) confirm the background Pb values previously proposed for the river system in the Belém region. The isotopic signatures of suspended matter on the eastern (206Pb/207Pb = 1.188) and western (206Pb/207Pb = 1.174) margins of Guajará Bay show that suspended matter is an efficient Pb trans¬portation mechanism of domestic and industrial wastewater from Belém to the western margin of the bay due to tidal effects at the confluence with Guamá River. The Pb isotopic compositions along the sediment cores show a decrease of the 206Pb/207Pb ratio to a value of 1,180 in the shallower 20cm of the cores from the western margin of Guajará Bay, not observed in the cores of Carnapijó River. This decrease indicates a probable anthropogenic contribution over the past 15 years in the western margin of the bay. The provenance of the bottom sediments in three areas of the Amazon Coastal Zone (mouth of the Amazon River, Golfão Marajoara and northeastern coast of Pará) was investigated by elemental and Sr-Nd-Pb isotopic geochemistry. The geochemical signatures of the bottom sediments from the three sectors indicate a provenance from felsic geological units of the upper continental crust. Sediments of the Southern Channel of the Amazon River, north of the Marajó island (mouth of the Amazon River) had lower contents of Na2O and K2O and a higher CIA, indicating a higher degree of weathering. The distinct isotopic signatures of Sr, Pb and, principally, Nd of bottom sediments of the three studied sectors indicate different sources in nature and age. The sediments of the mouth of the Amazon River derived predominantly from the Andean and sub-Andean regions, as already shown in previous works. The more radiogenic Sr signatures and more negative ƐNd values of the sediments from Guajará Bay and Carnapijó and Guamá rivers, in Belém area, Marajoara Gulf (0,7267< 87Sr/86Sr <0,7316; -17,97< ƐNd < -13,58) and from the estuaries of Caeté and Maracanã rivers, northeastern coast of Pará (0,7220< 87Sr/86Sr < 0,7264; -24,05< ƐNd<-17,58) indicate a greater contribution of Precambrian rocks in their sources. Nd-TDM model ages (1.62-1.99 Ga) of the sediments from the Golfão Marajoara suggest a predominant contribution from the metasedimentary units of the Araguaia Belt and a subordinated contribution from the magmatic and metamorphic basement of Tocantins Province. Nd-TDM model ages (1.70-2.83 Ga) of sediment in the estuaries of Maracanã and Caeté rivers portray a strong contribution of Precambrian basement rocks (Craton Fragments of San Luis and Gurupi Belt) that outcrop in coastal region of northeastern Pará.