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O presente artigo tem por objetivo sistematizar e analisar a contribuição e a importância da didática na formação do docente no ensino superior aplicado ao curso de estética e cosmética, as fontes para o levantamento da pesquisa foi a partir da revisão de literatura, com caráter exploratório, pesquisa de campo, embasado no método dialético. Baseado nas análises, o estudo apresentou uma síntese de cocntribuições no processo de ensino aprendizagem do docente do ensino superior, qualificando as diretrizes curriculares junto com a formação pedagógica. Ao final do estudo, foi possível compreender que a didática é conhecida, apreendida e aplicada efetivamente, tornar-se um instrumento facilitador do processo de ensino e aprendizagem necessário na prática docente.

Understanding the hydrosedimentological dynamics of tropical rivers is a challenge in the Amazon due to its remote and difficult-to-access areas. This study was based on data collected from 16 hydrosedimentological control sections in the 6 subbasins that make up the Itacaiúnas River Watershed (IRW), with 4 annual campaigns (high water levels, rising water levels, falling water levels, low water levels) between 2015 and 2019, with the aim of constructing and comparing sediment rating curves and sediment yield. The data at the mouth of the IRW revealed that the rainy season is responsible for 93% of liquid discharges (Q) with an average of 1460.88 m3/s and for 98% of suspended sediment discharges (SSQ) with an average of 5864.15 tons/day. Suspended sediment concentrations (SSCs) are low to moderate (50 to 150 mg/l). The curves encompassing all the data showed R2 values (0.92 to 0.99) greater than the curves with only the values of the rainy or dry season, indicating a good fit of the power equation to the SSQ and Q data for all sections studied. Higher values of coefficients a and b show areas of greater sediment production and deforestation, as well as areas with new sources of sediment and preserved forest. RESUMO Compreender a dinâmica hidrossedimentológica dos rios tropicais é um desafio, principalmente na Amazônia, devido às suas áreas remotas e de difícil acesso. Este estudo foi baseado em dados coletados em 16 seções hidrossedimentológicas de controle distribuídas nas 6 sub-bacias que compõem a bacia hidrográfica do Rio Itacaiúnas (BHRI), com 4 campanhas anuais (enchente, cheia, vazante e seca) entre 2015 e 2019, objetivando a construção e comparação da curva-chave de sedimentos e produção de sedimentos. Os dados na foz da bacia revelaram que o período chuvoso é responsável por 93% das descargas líquidas com médias de 1460,88 m3/s e por 98% das descargas de sedimentos em suspensão com média de 5864,15 ton/dia. As Concentrações de sedimentos em suspensão (CSSs) são baixas a moderadas (50 a 150 mg/l). As análises das curvas obtidas com todos os dados apresentaram R2 (0,92 a 0,99) maiores do que utilizando apenas os valores da estação chuvosa ou seca, mostrando um bom ajuste da equação de potência aos dados QSS e Q para todas as seções estudadas. Os maiores valores do coeficiente a e b indicam áreas de maior produção de sedimentos e desmatamento e áreas com novas fontes de sedimentos e floresta preservada.

Made available in DSpace on 2019-10-04T12:35:41Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-04-01 Vale Institute of Technology Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Statistical evaluation applied to geochemical data of upland lake sediments and their catchment basins rocks from Serra dos Carajas was used to identify geochemical signatures associated with underlying processes, sediment provenances, and source-sink relationship. The lakes are Violao, Amendoim and Tres Irmas - TI1, TI2 and TI3. A centred log-ratio transformation (clr) was used prior to multivariate analyses in order to eliminate closure issues in compositional data. Due to the similarity between delta N-15 values and organic sources (mainly from C3 plants), the three lakes were clustered together. Violao Lake receives largest organic contribution from autochthonous sources, such as siliceous sponge spicules and algae, except for it shallower portion (WNW extension), which is more similar to TI2, having low delta N-15 values that are similar to the isotopic signature of upland swamps. The upper continental crust (UCC) normalization pattern shows that sediments are mainly enriched in Fe, P and Se, which is closely related to the catchment lithology. The distribution of elements in TI2 is significantly different from the other lakes, because it is dominated by organic carbon, while the other lakes are a mix of detritus and organic carbon. Factor Analysis (FA) using clr-transformed data distinguishes several geochemical assemblages in the sediments, with the major detritic groups being similar to catchment basin laterites: the Ti-Zr-Hf-Nb-Y-HREEs group corresponds to resistant minerals which remained stable during lateritization; the LREEs group reflects mobilization and reprecipitation by REE bearing minerals; and the Al-V-Cr-Sc association reflects metavolcanic rock. The Fe-P-Mo-As-Zn cluster in the sediments is attributed to Fe-oxyhydroxide precipitation, while TOC-SO3-Hg-Se group is controlled by organic matter. Principal Component Analysis (PCA) further indicates that detritic lake sediments are not directly derived from the parent rocks, but from weathered crusts, mainly ferruginous laterites and soils, which is consistent with their elements ratios. Inst Tecnol Vale, Rua Boaventura da Silva 955, BR-66055090 Belem, Para, Brazil Univ Fed Para, Inst Geociencias, Programa Posgrad Geol & Geoquim, Av Augusto Correa 1 Guama, BR-66075110 Belem, Para, Brazil Geocon Environm Consulting, London, ON N6G 3H9, Canada Gerencia Meio Ambiente Minas Carajas, Dept Ferrosos Norte, Estr Raymundo Mascarenhas,S-N Mina N4, Parauapebas, Para, Brazil Univ Estadual Paulista, Inst Biociencias, Ctr Isotopos Estaveis, Rua Prof Dr Antonio Celso Wagner Zanin 250, BR-18618689 Botucatu, SP, Brazil Univ Estadual Paulista, Inst Biociencias, Ctr Isotopos Estaveis, Rua Prof Dr Antonio Celso Wagner Zanin 250, BR-18618689 Botucatu, SP, Brazil CNPq: 479182/2012-4 CNPq: 442088/2014-0 CNPq: 306108/2014-3 CNPq: 302839/2016-0 CNPq: 306450/2013-5

Trace elements (TE) contamination in forested areas of the Itacaiúnas River Watershed (IRW), Brazilian Amazon, arouses growing interest owing to the rapid deforestation and mining activities. In this study, soils (surface, SS; bottom, BS) and stream sediments (SD) from forested/deforested areas of IRW were analyzed with the aim of (1) evaluating the major sources of TE (mainly As, Ba, Cd, Cu, Co, Cr, Hg, Mo, Mn, Ni, Pb, V, and Zn), and (2) examining the soil-sediment TE link related to land-use change and/or geologic factors. Compositional data analysis (CoDA) was used to eliminate data closure issues and the centred log-ratio (clr) transformation yielded better results in Principal Component Analysis (PCA). The TE distribution pattern was significantly different (p 0.05) between forested and deforested areas, but in both areas the TE distribution pattern is significantly correlated between SS, BS, and SD, indicating a strong lithogenic control. PCA (clr-transformed) identified the major geochemical bedrock signature as Fe-Ti-V-Cu-Cr-Ni, which is nearly similar in soil and sediments. The more accentuated enrichment and the maximum number of anomalies of these elements were found in the Carajás Basin and are highly coincident with mineral deposits/local lithologies without clear indication of anthropogenic contamination from point sources. Besides geogenic factors, deforestation is also affecting TE distribution in the basin. In deforested areas, Mn was significantly enriched in the surface horizon. Furthermore, linear regression analysis shows stronger TE relationships between soils and sediments in deforested areas than in forested ones, reflecting higher erosion in the former. This could be the reason for the relatively higher enrichment of TE (e.g., Fe, Mn, Cu, Cr, Ni) in deforested sediments. The TE contamination using regional background values provides more accurate results than worldwide reference values. Thus, the former should be considered for a more realistic environmental risk assessment in IRW and other forest ecosystems in the Brazilian Amazon.

Geochemical survey in the Vermelho (VSB) and Sororo (SSB) sub-basins of the Itacaiunas basin in southeastern Amazonian region has shown that the physical-chemical parameters of stream water do not display accentuated variations between the rainy and dry seasons. Except for Fe and Mn, in general most metals show low contents in water and evidences of significant contamination were not observed. Higher contents were mostly registered during the rainy season. Fe is regularly distributed in water in the studied area and the increase of its concentration was favored by deforestation. Mn contents increase during the dry season possibly due to biogeochemical processes. High Fe and Mn contents in water are inherent to the specific local conditions prevalent in the Amazonian region. Geogenic influence in metal distribution in water is significant for Co, Cr, Cu, Ni, Pb, Sn, V, and Zn. Anthropic effects are subordinate except for Fe and Mn or in local areas. The definition of threshold values for As, Co, Cr, and Pb, was limited, however, threshold values for Cu, Ni, Sn, V, and Zn were estimated for at least one season in each sub-basin. Threshold values of total iron were obtained (5 to 6 mg/L and 2 to 3 mg/L in the rainy and dry seasons, respectively). Estimated Mn threshold values are 0.30 to 0.45 mg/L in the rainy season and in the dry season they decrease to 0.20 to 0.30 mg/L in VSB and increase to 1.3 to 1.4 mg/L in SSB.

This work aimed to understand the drivers of landscape evolution and floodplain formation in a Precambrian Shield area of southeastern Amazonia. This area evolved during the Quaternary into a denudational system with strong structural control, which produced valley side slopes between the Araguaia Belt (AB) and the topmost Parnaiba basin and narrow floodplains in the lower Vermelho River. These floodplains developed at approximately 11215–11410 cal yr BP with the deposition of muds on the weathered basement rocks of the Couto Magalhaes Formation in the Ab (CMF) long before sea-level stabilization on the Amazon coast. The chondrite- and upper continental crust-normalized patterns, along with Al/Ti and La/Th ratios, clearly indicate that muds were derived from the CMF-AB. The strong positive correlation of most of the trace elements and rare earth elements (REEs) with Al and Ti indicates their control by aluminous clay phases and a similar transport process. Overbank flows of the Vermelho River resulted in the deposition and vertical accretion of sands from the fluvial channel over the floodplain, forming discontinuous marginal levees after 4520–4710 cal yr BP. The accreted sands with the predominance of Si, Zr, and Hf and the depletion of most of the major and trace elements are likely associated with quartz enrichment and a strong sorting of heavy minerals, which is also supported by Al2O3/SiO2 vs Fe2O3/SiO2. The tributaries of the lower Vermelho River were active until 3890–4095 cal yr BP, and subsequently, the channel was abandoned as a result of the filling process. At approximately 3440–3560 cal yr BP, the floodplain was influenced by prolonged and severe droughts that fully exposed the muddy deposits and caused the enrichment of Fe-Mnoxyoxide phases. The affinity of most of the potentially toxic elements with Al signifies that these floodplain deposits are a natural record for geochemical background studies.

Made available in DSpace on 2018-11-26T17:44:23Z (GMT). No. of bitstreams: 0 Previous issue date: 2017-12-01 National Forest of Carajas Instituto Tecnologico Vale (Paleoclimate Project) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Lake Tres Irmas (LTI), the largest upland lake in the Brazilian Amazonia, located in Serra dos Carajas, was characterized using multi-elemental and isotope geochemistry (delta 13(C) and delta N-15) to understand the significance of organic and inorganic sources, weathering and sedimentary processes on the distribution of elements in lake bottom (surficial) sediments. Carbon and nitrogen isotopes from sedimentary organic matter suggest C3 terrestrial plants (forests > canga vegetation), macrophytes and freshwater DOC as the main sources. Sediments are depleted in most of the major oxides (except Fe2O3 and P2O5) when compared to upper continental crust (UCC) and their spatial distribution is highly influenced by catchment lithology. Principal Component Analysis revealed that most of the trace elements (Ba, Sr, Rb, Sc, Th, U, Zr, Hf, Nb, Y, V, Cr, Ga, Co, Ni) and REEs are closely correlated with Al and Ti (PC1; Group-1), so their redistribution is less influenced by post-depositional process. This is due to their relative immobility and being hosted by Al-bearing minerals during laterization. High Chemical Index of Alteration (CIA), Mafic Index of Alteration (MIA) and Index of Laterization (IOL) values indicate intense chemical weathering at source areas, but the weathering transformation was better quantified by IOL. A-CN-K plot along with elemental ratios (Al/K, Ti/K, Ti/zr, La/Al, Cr/Th, Co/Th, La/Sm, La/Gd, Zr/ Y, and Eu/Eu*) as well as chondrite-normalized REE patterns show that the detritic sediments are mainly sourced from ferruginous laterites and soils in the catchment, which may have characteristics similar to mafic rocks. (C) 2017 Elsevier Ltd. All rights reserved. Inst Tecnol Vale, Rua Boaventura da Silva 955, BR-66055090 Belem, Para, Brazil Univ Fed Para, Inst Geociencias, Programa Posgrad Geol & Geoquim, Av Augusta Correa 1, BR-66075110 Belem, Para, Brazil Geocon Environm Consulting, London, ON N6G 3H9, Canada Ctr Energia Nucl Agr, Lab C-14,Av Centenario 303, BR-13400970 Piracicaba, SP, Brazil Dept Ferrosos Norte, Gerencia Meio Ambiente Minas Carajas, Estr Raymundo Mascarenhas S-N Mina N4, BR-68516000 Parauapebas, Para, Brazil Univ Estadual Paulista, Inst Biociencias, Ctr Isotopos Estaveis, Dist Rubiao Jr S-N, BR-18618970 Botucatu, SP, Brazil Univ Estadual Paulista, Inst Biociencias, Ctr Isotopos Estaveis, Dist Rubiao Jr S-N, BR-18618970 Botucatu, SP, Brazil National Forest of Carajas: SISBIO 35594-2 CNPq: 442088/2014-0 CNPq: 302839/2016-0 CNPq: 306450/2013-5

The Amazon River is the largest fluvial source of freshwater and sediment to the global ocean and has the longest tidally influenced reach in the world. Two major rivers, the Tapajos and Xingu, enter the Amazon along its tidal reach. However, unlike most fluvial confluences, these are not one-way conduits through which water and sediment flow downstream toward the sea. The drowned river valleys (rias) at the confluences of the Tapajos and Xingu with the Amazon River experience water-level fluctuations associated not only with the seasonal rise and fall of the river network, but also with semidiurnal tides that propagate as far as 800 km up the Amazon River. Superimposed seasonal and tidal forcing, distinct sediment and temperature signatures of Amazon and tributary waters, and antecedent geomorphology combine to create mainstem–tributary confluences that act as sediment traps rather than sources of sediment. Hydrodynamic measurements are combined with data from sediment cores to determine the distribution of tributary-derived and Amazon-derived sediment within the ria basins, characterize the sediment-transport mechanisms within the confluence areas, and estimate rates of sediment accumulation within both rias. The Tapajos and Xingu ria basins trap the majority of the sediment carried by the tributaries themselves in addition to ca 20 Mt yr−1 of sediment sourced from the Amazon River. These findings have implications for the interpretation of stratigraphy associated with incised-valley systems, such as those that dominated the transfer of sediment to the oceans during lowstands in sea level. This article is protected by copyright. All rights reserved.

Several alternative interpretations of the pollen records of lake sediments in the Amazonia may arise due to a lack of understanding of the modern environments, mainly related to pollen–vegetation relationship. Therefore, in this work, we studied the modern pollen rain in sediments of the Amendoim Lake, plateaus of the Serra Sul dos Carajás, southeastern Amazonia. This study indicates the predominance of pollen grains from forest formation (ombrophilous forests and capão florestal) over montane savanna in the lake sediments, despite the fact that montane savanna occupies ~90% of the drainage basin. Additionally, these sediments reflect stronger signal of pollen from ombrophilous forests that occur in the slopes of the plateau. Important components of montane savanna such as Vellozia and Cereus were not observed in the modern pollen rain, which may be related to their shorter flowering periods restricted to the beginning of wetter conditions. The absence of Sacoglottis, Trichilia, Clusia, Emmotum, Guapira and Simarouba in the pollen rain is likely associated with different pollination strategy. The occurrence of windblown pollen of Alchornea, Pseudolmedia, Ilex and Cecropia, which are found from low to highlands of the Carajás region, reinforces a regional vegetation signal in sediments. Several plants from the studied site have been improperly described, according to taxonomy and ecology. For example, the current occurrence of Ilex and Styrax in the study site clearly suggests that they cannot be used as indicators of colder palaeoclimate conditions, as previously described. In addition, Poaceae can be found in drier to wetter substrate conditions, and abundance of their pollen grains in lakes can significantly vary according to relief morphology and cannot indicate palaeovegetation openness. Therefore, this work is a good background for further palaeobotany studies for this region.

A limnological investigation involving physical, chemical and biological aspects was undertaken in five tropical upland lakes (Violao − Vl, Amendoim − Am, and Tres Irmas − TI1, TI2 and TI3) from Serra dos Carajas, Brazil. Results show that these lakes are shallow, weakly stratified, and of polymictic type. These characteristics may have caused vertical mixing of limnological parameters. Seasonal changes were minor for most parameters, except for chlorophyll-a (Chl-a ) and cyanobacteria, which also showed considerable variation between lakes. In general, waters of these lakes were mostly acidic in nature (avg. pH 4.9–5.9), with high total Fe (up to 1.52 mg/L) and low electrolytic conductivity (avg. 8.13–14 μS/cm) and total phosphorus (TP) (avg. 10–35.5 μg/L). Although the water bodies have good quality and classified as class I and II types according to CONAMA Resolution No. 357/05, trophic state index (TSI) varies from ultra-oligotrophic to eutrophic state, with higher trophic state observed for Vl, TI1 and TI2. Limnological characteristics of these lakes is highly influenced by lithological and morphological parameters. Principal component analysis (PCA) reveals that Chl-a and cyanobacteria are not solely influenced by TP and lower concentrations of all these parameters in Am lake are probably due to specificities of its catchment lithology. Phytoplankton taxa in the lakes are characterized by small chroococcales groups and desmids together with filamentous algae, more commonly observed in the dry season. The zooplankton community in the lakes is mainly dominated by rotifers, followed by cladocerans and copepods. Regarding species richness, zooplankton was highest in Vl, while phytoplankton is highest in TI1, and this aspect is most likely related to lake water levels.

A multi-proxy geochemical study of surficial sediments of an upland lake (Amendoim Lake), located in the Serra dos Carajas region, Brazil, was carried out to understand catchment weathering and provenance of sediments in the basin, as well as sedimentary processes. The carbon and nitrogen isotopic compositions of organic matter in the sediment were quite homogeneous, and suggest that the organic sources for this lake are mainly composed of palms and submerged macrophytes. The R-mode factor analysis indicates that most of the trace elements, including rare earth elements (REEs), are clustered with Al (Group 1), Si is grouped with Zr and Hf (Group 4), total organic carbon (TOC) with TS and Hg (Group 2), and Fe with Mn and As (Group 3). The elements of the Group 1 show strong positive correlations with Al, suggesting that these elements are hosted in detrital minerals during laterization in the catchment basin and not significantly affected by diagenesis. The high CIA values (96–99) of sediments together with their position in A-CN-K and log (Fe2O3/K2O) vs log (SiO2/Al2O3) plots indicate intense chemical weathering in source area. However, similar geochemical signatures between lake sediments and catchment lateritic crust indicates that mechanical erosion was the dominant sediment formation process. REE patterns normalized to chondrite along with geochemical indices (Al/K, Al/Ti, La/Th, La/Al, Ti/Zr, Zr/Hf, Th/Sc, Co/Th, Ba/Sr, and Eu/Eu*) also indicate that the sediments are mainly derived from laterite crust. This study provides reliable background information to reconstruct weathering processes and lake evolution in the Serra dos Carajas area.

Upland lakes (ULs) of the Carajás, southeastern Amazonia, have been intensively studied to their evolution during the Quaternary, as well as the development of the associated biota. In this review, several classical and modern approaches from structural geology to the pollen rain and sedimentary data which cover an area of around 41,300 km2 were compiled. Multi-elemental geochemistry indicates that the detrital sediments derived from weathered crusts and soils, while the sedimentary organic matter represent autochthonous (siliceous sponge spicules, algae, macrophytes) and allochthonous (C3 plants and freshwater DOC) sources. Modern pollen rain suggests that even small lakes and canga areas can reflect forest signal, which depends on the topographic control and prevailing wind direction on pollen deposition. Integrated data of the sedimentary cores indicate that the active lakes never dried up during the last 50 ka cal BP. However, subaerial exposure occurs on filled lakes such as ST02 Lake during the LGM, LB3 and R2 lakes at the mid-Holocene due to drier paleoclimate conditions. Considering the organic proxies, only LB3 Lake presents expansion of C4 canga (montane savanna) plants since ULs of the Serra da Bocaína does not present siderites. Siderite formation on ULs deposits also points to drier paleoenviromental conditions, interrupting predominantly wet conditions. However, there is no evidence for widespread expansion of savanna into Southeastern Amazonia during the late Pleistocene and Holocene.

The present study compares the climatological normals for periods of 36 and 34 years (interpolated data) and observed precipitation and air temperature data (2015 and 2016) for four weather stations located within the boundaries of the Itacaiunas River Watershed (IRW), with the historical data from the Maraba station in the eastern Amazon used as control data. Both the interpolated and observed data were validated with the control data. The quantile technique was used to identify annual precipitation intensity thresholds and seasonal periods. A comparison was made with the precipitation and air temperature data to determine the effects of ENSO events during the period from 1980 to 2016. Our results regarding annual variability showed that the Onca Puma station was the rainiest among the subareas studied. The month of March was characterized as the rainiest month, and July was the least rainy for the watershed area. The influence of ENSO events on air temperature occurred in the early years, from 1980 to 2003, and the stronger events had a greater influence on precipitation in the IRW area. The 2015/16 El Nino may have had a more pronounced effect on the rainfall behavior at the Fazenda Abadia and Sossego stations. In the Salobo station (forest area), there was a delay in precipitation curves related to the occurrence of ENSO events, which may be associated with temporal variations in the dynamics of soil-vegetation-atmosphere interactions.

The application of sustainability principles to mining activities remains challenging. Explorations of non-renewable natural resources are irreversible; however, they can be better compensated for if the profit resulting from extraction is reinvested in social and human well-being and if environmental impacts are repaired. Thus, the evaluation of mining sustainability is necessary and requires efficient indicators to measure economic, social, and environmental performance. Here, we present the composite environmental sustainability index [CESI] of the landscape for iron mines in the Carajas National Forest, a protected site in the Brazilian Amazon. The index integrates 20 individual environmental indicators related to (1) changes in land cover and land use, (2) direct impacts caused by operations, (3) residue disposal and management, (4) energy, water, and soil resources, and (5) compensation for environmental damage. To define the threshold values for classifying individual indicators, we use legal requirements, data from the literature and historical time series. The values obtained for each of the individual indicators were normalized in terms of linguistic criteria, such as unsustainability (1), low sustainability (2) and high sustainability (3). The sustainability index of each of the five categories was calculated and based on these values, we computed the CESI of the physical mining environment. The values presented here represent baselines for further monitoring and evaluating the sustainability of the physical environment, guaranteeing iron ore exploitation in Carajas mining region with minimum environmental impacts. The proposed index can indicate a path towards environmental sustainability, especially in protected areas.

This study aims at providing high quality soil geochemical data at a regional scale (1 sample per 25 km2) to understand the source and distribution of potentially toxic elements (PTEs: Al, As, Ba, Cd, Cu, Co, Cr, Fe, Hg, Mo, Mn, Ni, Pb, Se, U, V, and Zn) and to define their geochemical background threshold values (GBTVs) in the Itacaiunas River Basin (IRB), Brazilian Amazon. A total of 2958 soil samples were collected at two depths (surface: 0–10 cm; bottom: 30–50 cm) and the fine fractions ( 98th > TIF or MAD > TIF > 98th, and overall the anomalies are mostly related to the local lithology/mineralization with no indication of anthropogenic contamination. Compared with Brazilian guidelines (CONAMA Resolution No. 420/2009), the GBTVs determined for Cr, Co, Ni, and Cu by TIF, MAD, and 98th percentile mostly exceeded both IV and PV limits. However, these high values are due to the influence of local lithology. This reveals that the Brazilian CONAMA guidelines of these elements for the IRB are unrealistic because that suggests a large number of sites requiring investigation, which is not consistent with the geochemical evidence. Therefore, site-specific GBTVs must be considered for the accurate evaluation of anthropogenic contamination, as well as the ecological and human health risks of PTEs in this region.

Multi-elemental analysis of high-density (regional-scale) geochemical surveys is an important strategy for multi-purpose applications, particularly in addressing geochemical background concentrations in different sampling media. This approach was applied to the Itacaiunas River Watershed (IRW), which is situated in the most prominent mining area of Brazil, the Carajas Mineral Province. Microcatchment-based mapping (~50 km2 each) covering the whole extent of IRW was delimited using remote sensing techniques and targeted for sampling. A total of 788 samples, including 27 duplicates, were collected in 2017. The

High-resolution satellite images, digital elevation models, bathymetric and sedimentological surveys coupled with statistical analysis were used to understand the physical environment and discuss their influence on water quality of the five upland lakes of Serra Sul dos Carajás, southeast Amazonia. The lakes have mid-altitude ranges (elevation), very small (catchment) and shallow to very shallow (central basins). Based on the length, area and volume, Violão and TI (Três Irmãs)-3 lakes may present large vertical movements of the water due to wind action and weakly stratified waters. Trophic conditions based on depth and shore development (Ld) parameters must be used with caution, since Amendoim Lake is relatively deep, but it is oligotrophic to ultra-oligotrophic. Ld values suggest that the lakes are circular to subcircular and are likely formed by solution process, as also suggested by volume development. TI-2 Lake is only presenting convex central basin and has highest dynamic ratio (DR), thus it may have high sedimentation and erosion rates. Based on the relationship between studied parameters, morphometric index and DR likely influence temperature and dissolved oxygen of waters of TI-2 Lake due to its depth profile and wind-induced surface mixing. Nevertheless, water quality parameters are controlled by catchment characteristics of the lakes.

Geochemical and isotopic compositions of surficial sediments from a plateau lake in Carajas, Southeastern Amazon region, were investigated to understand the spatial distribution of major and trace elements, δ13C, δ15N, and C/N ratio, depositional processes, and the origin of inorganic and organic fractions. The δ13C, δ15N, and C/N ratio indicate mainly an autochthonous source, with siliceous sponge spicules and algae being the major source of organic matter in the center of the lake (Sector 3), while an allochthonous source, mainly derived from C3 vascular forest plants dominates in the shallowest portion of the lake (Sector 1). Consequently, there was an apparent dilution of C4 plants (montane savanna) in the sediment/water interface. Among major elements, Fe2O3 is highly enriched in Sector 3, which is controlled by the erosion of catchment laterites and underwater topography, while Al2O3 and P2O5 enrichment near the northern border of the lake is controlled by the weathering of mafic rocks. Similar spatial distribution of SiO2 with total organic carbon (TOC) and isotopic evidence indicate that Si distribution is partially controlled by organic components such as siliceous sponge spicules and algae. The occurrence of most of the trace and rare earth elements (REE) is independent of Fe2O3 and TOC, but controlled by detrital aluminum silicates and heavy minerals, indicating a lack of post-depositional diagenetic control on their distribution. The distribution of As and Mo are possibly controlled by organic matter mineralization during early diagenesis and subsequently precipitation of Fe phases. The values of the chemical index of alteration (CIA) in the sediments are very high (94–99) and similar to those of the source rocks, suggesting that sediment composition is mainly controlled by mechanical weathering, rather than chemical weathering. Geochemical indices (Al/K, Ti/K, Al/Ti, La/Th, Ti/Zr, Zr/Hf, Hf/Nb, La/Al, Co/Th, Ba/Sr, and Th/Sc), together with the A–CN–K plot, suggest that the provenance of the inorganic sediments remained relatively uniform or constant during the depositional period, and that they were mainly derived from laterite crusts and subordinately from mafic soils. This inference was further substantiated by the chondrite-normalized REE patterns and discrimination plots. Geochemical indices such as U/Th, authigenic-U, Mo/Al, and V/Cr indicate that the sediments were deposited under an oxic environment.

Down-core changes in sedimentary facies, elemental geochemistry, pollen, spore, δ13C, δ15N and radiocarbon records from a filled lake, named R4, of the Serra Sul dos Carajás were used to study the relationship between the paleomorphological and paleoecological processes and their significance for Holocene paleoclimatology of the southeast Amazonia. The sediment deposition of the R4 lake started around 9500 cal yr BP. Increase of detrital components from 9500 to 7000 cal yr BP suggests high weathering of surrounding catchment rocks and soils, and deposition into the lake basin under mudflows. At that time, montane savanna and forest formation were already established suggesting predominance of wet climate. However, from 7000 to 3000 cal yr BP, a decline of detrital input occurred. Also, forest formation and pteridophytes were declined, while palms and macrophytes were remained relatively stable, indicating that water levels of the lake is likely dropped allowing the development of plants adapted to subaerial condition under drier climate conditions. After 3000 cal yr BP, eutrophication and low accommodation space lead to high lake productivity and the final stage of the lake filling respectively, and forest formation may has acquired its current structure, which suggests return of wetter climate conditions. SOUZA FILHO, P. W. M. Universidade Federal do Pará

A high resolution systematic geochemical mapping at regional-scale is considered to be the best available method to estimate geochemical baseline levels of trace elements in stream water, and is an essential part of environmental risk assessment. This methodology was applied in a project in the Itacaiunas River Basin, southeastern Amazon, Brazil, which includes several mines of the Carajas Mineral Province (as part of the Itacaiunas Geochemical Mapping and Background Project, ItacGMBP). A total of 1429 samples (including 55 duplicates) were collected in 2017 at 900 sites at one sample per microbasin, during both dry and rainy periods. The analyses of 34 elements were carried out using Inductively Coupled Plasma Mass Spectrometry (ICP-MS). In general, the waters are slightly alkaline and are classified as mixed Ca-Na-HCO3 type, indicating that they are mainly influenced by silicate rock weathering. Most metal concentrations in the water are low, except Fe and Mn. Seasonality explains differences in metal concentrations, with higher values being obtained in the rainy season. Baseline threshold values (BTVs) were calculated separately for both seasons by employing different statistical methods: iterative 2σ and DF preferentially delivered a more restrictive or conservative levels, which can be represenative of the natural BTVs (NBTVs), considering as the least degraded with low or no significant level of anthropogenic influence; and 98th percentile provides the ambient BTVs (ABTVs), which consists of natural plus diffuse anthropogenic input in the defined area. The ABTVs of Fe and Mn significantly exceed the WHO (1998) and CONAMA 357/05 limits. Spatial distribution indicates that Fe and Mn are not strictly related to geologic setting, rather they are highly influenced by specific local land use as well as deep weathering of the catchment and intense leaching and run-off during the rainy season. However, higher Mn occurrence in the dry period results from redox cycling of Fe and Mn via biogeochemical processes. The ABTVs of Ni, Cr, and V are controlled by bedrock lithology (geologic setting), mainly associated with mafic-ultramafic rocks; Cu is associated with two large hydrothermally mineralized copper belts. The estimation of baseline levels of As, Se, and Pb were highly limited due to of the large number of samples with results less than detection limits, in this case the 95th percentile was used for their BTVs. Geochemical data as well as anomalous values for most of the metals indicate that anthropogenic influence from point sources is highly negligible in the basin, except at a few points, where high NO3- has been observed, probably due to more intense human and livestock activity. This study demonstrates that site-specific geochemical baseline assessment is a crucial factor when evaluating surficial water conditions in a large basin.

Limnological characteristics of the Violão and Amendoim lakes, in the Serra dos Carajás, Amazon, were studied interannually (2013-2014). Climate data indicate anomalous conditions during the 2013 rainy period with higher rainfall and lower temperature in the beginning (November). Lake levels were influenced after the first and second hour of each rainfall, which showed a strong synchronization between seasonal fluctuation of lake levels and local weather patterns. Based on the water quality, both lakes are classified as classes "1" and "2" in the CONAMA (Conselho Nacional do Meio Ambiente) scheme and as "excellent" to "good" in the WQI (Water Quality Index) categories. However, the limnology is distinctly different between the lakes and seasons. Higher trophic state and phytoplankton productivity were observed mainly during the rainy period in Violão Lake compared to Amendoim Lake. This may be due to deposition of leached nutrients in the former, mainly total phosphorus (TP), which was probably derived from mafic soils and guano. This is consistent with the significant positive correlation between Chlorophyll-a and TP at the end of the rainy period (March-April), whereas this was not observed in the beginning (November). This could possibly be a consequence of the more intense cloud cover, and unusual high rainfall that limits nutrient availability.

The hydrodynamics, morphology and sedimentology of the Taperaçu estuary were investigated. This is one of several estuaries located within the largest mangrove fringe in the world, bordering the Amazon region, subject to a macrotidal regime and regionally atypical negligible fresh water supply. The results reveal widespread sand banks that occupy the central portion of the estuarine cross-section. Well-sorted very fine sandy sediments of marine origin prevail. Shorter flood phases, with substantially higher current velocities, were observed in the upper sector of Taperaçu, as expected for a shallow, friction-dominated estuary. However, ebb domination can be expected for estuaries with large associated mangrove areas and substantial estuarine infilling, both of which situations occur on the Taperaçu. The tidal asymmetry favoring flood currents could be the result of the absence of an effective fluvial discharge. Furthermore, it was observed that the Taperaçu is connected by tidal creeks to the neighboring Caeté estuary, allowing a stronger flux during the flood and intensifying the higher flood currents. As a whole, the results have shown a complex interaction of morphological aspects (friction, fluvial drainage, connections with neighbor estuaries, infilling and large storage area) in determining hydrodynamic patterns, thus improving the understanding of Amazon estuaries.A hidrodinâmica, morfologia e sedimentologia do estuário do Taperaçu foram investigadas. Este é um entre vários estuários do litoral amazônico que integram a maior extensão contínua de manguezais do mundo, apresentando uma descarga de água doce muito reduzida, atípica para a região. Os resultados revelam grandes bancos arenosos que ocupam em grande parte a porção central do estuário. Areias muito finas e bem selecionadas de origem marinha prevalecem. Fases de enchente mais curtas, com velocidades de corrente substancialmente mais altas, são observadas na porção superior do estuário, como esperado para um estuário raso e dominado por fricção. Por outro lado, uma vazante mais intensa poderia ocorrer como resultado de grandes áreas de manguezais associadas e intenso preenchimento estuarino, sendo que ambas as condições são observadas no Taperaçu. Neste caso, a prevalência da enchente parece estar associada à ausência de uma descarga fluvial efetiva. Além disso, alguns canais de maré conectam o Taperaçu com seu vizinho estuário do Caeté, o que contribuiria para o domínio de enchente. Como um todo, os resultados demonstram uma complexa interação de aspectos de configuração (fricção, drenagem fluvial, conexões com estuários vizinhos, preenchimento e grandes áreas intermareais) na determinação dos padrões hidrodinâmicos, contribuindo para o entendimento dos estuários da região amazônica.