A mineração de areia é uma atividade importante, mas provoca impactos ambientais, como perda de biodiversidade e degradação dos solos. Em áreas de Campinaranas, os impactos são ainda maiores, pois esses ecossistemas são frágeis e pobres em nutrientes. A capacidade de colonização e regeneração natural desses solos é extremamente limitada e ainda não se conhece uma técnica eficaz e eficiente de recuperação. O cultivo de adubos verdes, especialmente leguminosas fixadoras de nitrogênio, pode ajudar na recuperação de solos degradados. Tais plantas melhoram as condições do solo, como fertilidade, estrutura e cobertura vegetal. Assim, objetivou se avaliar a produção de biomassa do feijão guandu (Cajanus cajan) e do feijão de porco (Canavalia ensiformes) em substrato proveniente de áreas mineradas. O experimento foi conduzido em casa de vegetação, usando cinco níveis de adubação e cinco repetições em um esquema fatorial 5 x 2, inteiramente casualizado. Foram avaliadas as variáveis massa seca da parte aérea (MSPA), da raiz (MSR) e total (MST). Os dados foram submetidos a análise de variância. Tendo em vista que houve significância, foram comparadas por meio do teste Tukey a 5% de probabilidade, usando o programa de análises estatísticas IBM SPSS Statistics 25. Na produção de MSPA e MST, o tratamento 5 foi o mais eficiente para as duas espécies e na produção de MSR, o tratamento 4 foi o mais eficiente para ambas. Os resultados sugerem que o cultivo de leguminosas fixadoras de nitrogênio pode ser uma estratégia eficaz para a recuperação de solos degradados por mineração de areia.

ABSTRACT Amazonian Dark Earths (ADEs) are archaeological soils with darkened anthropic horizons, fragments of charcoal ceramics, and enriched in P, Ca2+, Mg2+, Mn, Zn, and organic matter. They mainly occur in Terra Firme, adjacent to river banks, rarely being recorded in Várzeas. The Solimões River remains practically unexplored in ADE studies. To fill this gap, seven ADE soil profiles were studied in this unexplored region, five in Terra Firme and two in Várzea areas, between São Paulo de Olivença and Amaturá (Alto Solimões, Amazonas). Morphological, physical, and chemical analyses were carried out, complemented by P-form extraction and radiocarbon dating. The morphology of the dark surface shows the abundance of pyrogenic charcoal and ceramics. The high chemical status is confirmed by high levels of P, Ca2+, Mg2+, Mn, Zn, Sum of Bases, CEC, and TOC. There is a marked illuviation of clay, accompanied by OM, P and Ca2+, with increasing P contents underground. The P fractions reveal a predominance of P-Ca for the anthropic horizons in Várzeas, whereas P-Al and P-Fe dominate the anthropic horizons of Terra Firme, with few exceptions. The radiocarbon ages of the Terra Firme ADEs in Alto Solimões range from 1190 – 1410 years BP (younger) to 2500-2870 years BP (older), indicating an ancient Late Holocene occupation of drained soils along river banks. In contrast, Várzea ADEs range from 920 to 1270 years BP, indicating a later occupation period after the settlement of adjacent Terra Firme (uplands). Although we present only a provisional account based on a few sites, we postulate that the first settlers in Alto Solimões occupied the Terra Firme area adjacent to the main rivers and later diversified into the Várzeas (floodplains). This pattern of a complementary Várzea-Terra Firme ADE continuum is recurring throughout the Amazonas-Solimões system, as revealed by the new archaeological sites analyzed. The ADEs of Upper Solimões Várzeas show greater chemical fertility than Terra Firme areas. Similar to the Middle Amazon Valley, but they form unusual mounds not observed in the Middle Amazon, suggesting that different floodplain hydrological regimes account for these features. Phosphorus-Ca forms are the primary source of P, which are progressively transformed into P-Al and P-Fe forms with advancing pedogenesis in the most acidic environments of Terra Firme. The unprecedented presence of anthropogenic landforms in the Alto Solimões floodplains demands a more comprehensive investigation of the region to uncover the pre-Colombian cultural occupation and chronology in a key area of the Amazon Basin.

Recent studies identified the presence of Amazonian Dark Earths (ADE - anthropogenic soils) at the floodplains, similarly to the well-known ADE of the upland. Previously, different parameters have been established for characterizing ADE anthropic horizons, but they are unlikely to be useful in ill-drained environments of the hydromorphic Amazon floodplain. It raises the question of to what extent can the established parameters of ADE be applied to anthropic horizons at floodplains, and what other characteristics or attributes could be used as criteria for identifying and classifying anthropic horizons in those environments. The main hypothesis is that the ADE are contrasting to typical ADE found in the uplands. So, we selected eleven representative soil profiles in the Amazon River floodplain between the cities of Coari and Careiro da Varzea, in the Amazonas State - Brazil. Soils were described, sampled and classified according to the Brazilian Soil Classification and the World Reference Base for Soil Resoucers (WRB) System. Morphological, chemical and physical attributes were described and determined. The results indicated that pH value, the organic C (OC) and Cu concentration can be characteristic for upland ADE, but not for the buried Anthrosols from the floodplain. The concentration of OC required by the IUSS Working Group WRB (2022) as one of the criteria for pretic horizon, was not reached in all soils, and some could not be considered an Anthrosol for having less than 0,6 % OC even though all other criteria were met. We postulate that this criteria should be changed in such a way that these soils classify as Anthrosols. However, other soil attributes normally used as indicators of anthropic influence on upland ADE are also noticed on floodplain soils such as: high available or total P (in Mehlich-1 or total), Ca (Ca2+ or CaO), Zn (Mehlich-1 or total). It was further observed that the total concentrations of Ba, Cu and Sr also proved to be good indicators of anthropic horizons of floodplains buried soils. Hence, differential soil attributes can be used as proxies of Anthrosols presence in Amazon floodplain soils, enlarging the extent of these soils in the Amazonian landscape.

A mineração de areia é uma atividade econômica importante e necessária que provoca perda da biodiversidade e degradação dos solos. Nas áreas de Campinaranas, os impactos da mineração são ainda mais preocupantes por se tratar de ecossistemas frágeis e extremamente pobres em nutrientes para os quais não se conhece uma técnica eficaz e eficiente de recuperação. O cultivo de adubos verdes, especialmente leguminosas fixadoras de nitrogênio, promovem melhorias nos ambientes degradados como incorporação de matéria, cobertura do solo com consequente redução da temperatura da camada superficial, aumento da atividade microbiana e criando as condições mínimas necessárias para o cultivo de espécies nativas das Campinaranas e a restauração do ecossistema. Através deste estudo selecionou-se adubos verdes para a recuperação de solos arenosos degradados por mineração de areia. Para tanto avaliou-se o desenvolvimento de C. juncea e M. nivea em substrato proveniente de áreas mineradas. O ensaio foi conduzido em casa de vegetação usando como substrato a matriz mineral de áreas degradadas, cinco níveis de adubação, duas espécies de leguminosas e cinco repetições em um esquema fatorial 5 x 2, inteiramente casualizado. Cada repetição consistiu de um vaso contendo 5 litros de material e 3 plantas. Foram avaliadas as seguintes variáveis: massa seca da parte aérea, raiz e massa seca total. As médias foram comparadas pelo do teste de Tukey ao nível de 5% de significância, usando programa de análise estatística RStudio. A M. nivea obteve os melhores resultados na produção de massa seca total.

Translator Solos arenosos que ocorrem próximo a centros urbanos são impactados pela atividade exploratória da mineração. No Amazonas essas áreas estão associadas a Campinaranas, cuja fragilidade do ecossistema torna importante a ampliação de conhecimento para compor planos de restauração eficientes. O objetivo deste estudo foi caracterizar e classificar solos arenosos sob Campinaranas de dois municípios da região metropolitana de Manaus. Foram selecionadas cinco áreas em Manaus e Presidente Figueiredo, onde perfis foram abertos para caracterização morfológica, química, física e mineralógica do solo. Os perfis 01, 02 e 03 foram classificados como Neossolo Quartzarênico Órtico típico, o Perfil 4 como Espodossolo Humilúvico Órtico dúrico e o Perfil 5 como Neossolo Quartzarênico Órtico espodossólico. Os solos analisados apresentaram consistência solta a muito friável, com textura variando de franco arenosa a areia. Os teores de argila foram baixos, resultando em baixa densidade e alta porosidade. A acidez variou de fortemente ácida à extremamente ácida, com maiores concentrações de H+Al e Al3+ nos horizontes superficiais. O carbono orgânico total apresentou maiores concentrações nos horizontes superficiais e no horizonte Bh do P04. A capacidade de troca de cátions efetiva e total também foram maiores em superfície e nos horizontes Bh (P04) e C4 (P05). Em relação a mineralogia, foram encontradas maiores proporções de formas cristalinas de Al2O3 e Fe2O3 em comparação com as formas amorfas, principalmente no Bh (P04) e em agregados de matéria orgânica no P03, evidenciando o processo de podzolização e a influência do Al na formação desse solo.

Anthropic actions have motivated pieces of research on the impacted naturally poor soils of the Brazilian Amazon, requiring the use of diagnostic attributes that are increasingly specific to each environmental change. The use of magnetic proxies inherent in the soil may be the key to understanding the changes that occur in the soil and the environment. Therefore, this study aimed to characterize the physical, chemical and mineralogical properties of Alisols, in addition to determining the intensity and origin of the magnetic signal for future calibrations as an environmental proxy for monitoring soil fertility. One natural and three cultivated Alisols were sampled using systematic meshes in three layers: 0-5, 5-10 and 10-20 cm. The natural Alisol is a tropical forest and the agricultural ones refer to the cultivation of annatto, cupua & ccedil;u and guarana. A total of 192 samples/area were submitted to physical, chemical, mineralogical and magnetic susceptibility (MS) analysis. MS measured at low and high frequency and converted to specific mass (chi lf and chi hf), then descriptive, univariate and multivariate statistical analyzes were applied to the results. The conversion of the physically good and chemically poor and acidic natural Alisols to agricultural crops, caused an increase in the density and amplitude of the pH in water and Al3+ of the soil, plus a reduction in macroporosity, gravimetric humidity, available phosphorus and iron oxalate contents, and the incorporation of organic carbon in depth. All Alisols showed low chi lf and chi hf. However, chi lf values decreased in depth for cultivated Alisols (0.53-0.26 x 10-6 m3 kg- 1), whereas, for natural Alisol, these values tended to increase towards the subsurface (0.21-0.23 x 10-6 m3 kg- 1). Nevertheless, the value of chi lf and chi hf were highly representative within the cultivation areas, which was characterized as a suitable proxy to monitor the fertility of the Alisols in the Amazon region.

Recent studies identified the presence of Amazonian Dark Earths (ADE - anthropic horizons) at the floodplains, similarly to the well-known ADE of the upland. Previously, different parameters have been established for characterizing ADE anthropic horizons, but they are unlikely to be of use in ill-drained environments of the hydromorphic Amazon floodplain. It raises the question of to what extent can the established parameters of ADE be applied to anthropic horizons at floodplains, and what other characteristics could be used as criteria for identifying and classifying anthropic horizons in those environments. The main hypothesis is that the ADE are not like typical ADE found in the uplands. So, we selected eleven representative soil profiles in the Amazon River floodplains between the cities of Coari and Careiro da Várzea, in the Amazonas State - Brazil. Soils were described, sampled and classified according to the Brazilian Soil Classification and the World Reference Base for Soil Resoucers (WRB) System. Morphological, chemical and physical attributes were determined. The results indicated that pH value, the organic C (OC) and Cu concentration can be a characteristic for upland ADE, but not for the buried Anthrosols from the floodplain. The concentration of OC required by the IUSS Working Group WRB (2022) as one of the defining criteria for pretic horizon, was not reached in all soils, and some could not be considered an Anthrosol for having less than 0,6 % OC even though all other criteria were met. Due to the low OC content, they do not have a pretic horizon and do not classify as Anthrosols. In our opinion, the criteria should be changed in such a way that these soils classify as Anthrosols. However, other soil attributes normally used as indicators of anthropic influence on upland ADE are also noticed on floodplain soils such as: high available or total P (in Mehlich-1 or total), Ca (Ca2+ or CaO), Zn (Mehlich-1 or total). It was further observed that the total concentrations of Ba, Cu and Sr also proved to be good indicators of anthropic horizons of floodplains buried soils. Hence, differential soil attributes can be used as proxies of Anthrosols presence in Amazon floodplain soils, enlarging the extent of these soils in the Amazonian landscape.

Despite the existence of various studies on Archaeological Dark Earth - ADE, there is still a very large gap concerning the Amazon region, with many areas remaining unexplored scientifically. The aim of this study, therefore, was to characterize and classify areas of Archaeological Dark Earth located on rural properties and in one riverside community in the southern mesoregion of the state of Roraima. At these locations, trenches were dug in a total of 13 areas, and the profiles morphologically characterized and sampled for soil classification and Carbon-14 dating. The areas were georeferenced and measured, and the history of land use was described, together with the predominant vegetation in the region. The following physical analyses were carried out: texture and bulk density. The chemical analysis consisted of pH in water and KCl, exchangeable cations, exchangeable Al, available P, titratable acidity (H+Al), total N and organic matter. To produce the maps, computational processing was used in a Geographic Information System - GIS, employing geoprocessing tools with the aid of the ArcGIS v10.6 software; the attributes prepared from SRTM images were drainage network and terrain. Using the Brazilian System of Soil Classification (SiBCS), the profiles were classified as: Argissolos Amarelos, Cambissolo Háplico, Latossolos Amarelos, Argissolo Vermelho Amarelo, and Nitossolo Vermelho. It is suggested that the anthropogenic subgroup be included in the SiBCS. With the exception of 3 horizons, the anthropogenic horizon of each of the profiles sampled in the region has a eutrophic character, with ages that range from 1,120 to 1,864 years before present (YBP). Each of the areas of ADE is associated with a drainage network ranging from a small creek, approximately 6m wide, to a fast-flowing river, such as the Branco River, which is over 1,700m wide. The 13 areas are located in places away from the flood area that show little variation in relief, with a predominance of flat to gently undulating terrain.

The geochemical processes involved in the Amazon soils formation are not totally understood because its geological and pedological features were formed during different geological events and different times. The Southwestern region of Amazonas State is an example of a region where the soils were developed from rocks formed by sedimentary processes and, nowadays, the soils continue receiving seasonal inputs from the Andes sediments. Data on geochemical patterns of this region are scarce, and there is no information about the possible effects of the natural or unnatural enrichment of potentially toxic elements (PTEs). Thus, this study represents the first research into the geochemical patterns of PTEs in soils of Southwestern Amazonas State. Further, we carried out a human health risk assessment and a proposal for Quality Reference Values (QRV) for thirteen PTEs (As, Ba, Cd, Co, Cr, Cu, Mn, Ni, Pb, Ti, V, Zn and Zr). Our findings showed that the PTEs contents in soil samples collected in the lowland areas are strongly influenced by sediments inputs, while samples localized in the highland areas are weakly influenced by sediments inputs and present depletion of PTEs. Barium, Cr, Cu, Ni and Pb were the PTEs most influenced by sediment's deposition. The soil contamination assessment showed the existence of enrichment of the potentially toxic elements in soil samples, which may be a consequence of the natural inputs of the Andean sediments. Furthermore, Co and Cr exceed the safety zone for carcinogenic risk assessment, which indicates the need to monitor these elements and their possible effects on the health of the population in this region.

The Brazilian Amazonia region can be conveniently separated into 11 sectors, which represent large pedoenvironments at a continental scale. In a global panorama of the region, from this simplified and useful division, there is a high pedodiversity in the Amazon, despite the predominantly monotonous landforms, at macroscale. Soils of the Sedimentary Basins vary according to strong geological-structural control, coincident with the division of the sub-basins. Close to the Andes fold belt, soils of the Acre Basin, above the Iquitos Arch, have an Andean influence and are mostly young (Cambissolos, Luvissolos, and Argissolos), eutrophic, and high-activity clay. However, the aluminic character is very common. Between the Iquitos and Purus Archs, in the Solimões or Upper Amazonas basin, soils have Plinthite to varying degrees (Plintossolos and Argissolos), but mostly dystrophic. Downstream the Purus Arch to the Monte Alegre Arch, the mid-Amazon basin is strongly associated with Latossolos or Argissolos (always dystrophic), usually yellowish, derived from the pre-weathered Alter do Chão or Belterra Formations. At the low Amazon and Marajó island, under the influence of strong marine tides and by the gigantic sedimentary and hydrological load of the great Amazon river, extensive floodplains have Neossolos Flúvicos, Gleissolos, Plintossolos, and Planossolos. In the crystalline basement rocks of the Amazon Craton, gently dissected landforms reveal dominance of Argissolos or Latossolos (yellow and red-yellow), and generally dystrophic, except where mafic rocks occur. The floodplain soils of the tributaries are almost always dystrophic. The presence of petroplinthite in shallow soils under wet climates suggests that they formed under past climates much drier than the present ones. Anthropogenic soilsAnthropogenic soils (Indian Black Earths), with high levels of SOM, Available P, and CEC, occur frequently not only on the bluffs above the floodplain on well-drained lands of the Amazon region, but also on the Várzea floodplain, as buried paleosols. The Roraima and Rondônia Highlands have varying shallow or deep, dystrophic or eutrophic soils, depending on landforms and lithology. A few high-fertility soils, derived from mafic rocks, occur in both highland regions and are usually intensively cultivated. Sandy soils resulting from the extreme podzolizationPodzolization, with the formation of deep, acidic and chemically poor Espodossolos, are characteristic of the Rio Negro Basin. They occur in extensive flat and low-lying plains, under Campinarana vegetation. These extensive Tropical PodzolsTropical podzol were formed by the clay destruction of a previous Latossolos mantle under super humid climates. Also, Savanna islands (cerrado, campos) occur throughout Amazonia, and are mostly associated with poorly drained or imperfectly drained soils, but may also occur in higher ground (yellow Latossolos), impermeable parent materials (Monte Alegre) or sandy soils (Alter from the ground). They are floristically much poorer, compared to the core savannas of the Central Plateau. The Amazon/Solimões River floodplains, together with the Purus and Juruá rivers, constitute the largest eutrophic alluvial space in Brazil, and one of the most extensive worldwide, making the use and sustainable cultivation virtually continuous since pre-Columbian times.

Rare earth elements (REEs) are generally defined as a homogenous group of elements with similar physical-chemical properties, encompassing Y and Sc and the lanthanides elements series. Natural REEs contents in soils depend on the parent material, the soil genesis processes and can be gradually added to the soil by anthropogenic activities. The REEs have been considered emerging pollutants in several countries, so the establishment of regulatory guidelines is necessary to avoid environmental contamination. In Brazil, REE soils data are restricted to some regions, and knowledge about them in the Amazon soils is scarce, although this biome covers more than 40% of the Brazilian territory. Thus, the objectives of this study were to determine the REE content in soils of two hydrographic basins (Solimões and Rio Negro) of the Amazon biome, establish their Quality Reference Values (QRV) and to investigate the existence of enrichment of REEs in urban soils. The ΣREE(Y + Sc) content of Solimões surface samples was 109.28 mg kg-1 and the ΣREE(Y + Sc) content in the subsurface samples was 94.11 mg kg-1. In soils of Rio Negro basin, the ΣREE(Y + Sc) was 43.95 15 mg kg-1 surface samples and 38.40 mg kg-1 in subsurface samples. The ΣREE(Y + Sc) in urban topsoils samples was 38.62 mg kg-1. The REEs contents pattern in three studied areas are influenced in different amplitude by natural soil properties. The REEs content in urban topsoils were slightly higher than the Rio Negro pristine soils, but the ecological risk was low. QRVs recommend for Solimões soils ranged from 0.01 (Lu) to 145.6 mg kg-1 (Ce) and for Rio Negro soils ranged from 0.05 (Lu) to 15.8 mg kg-1 (Ce).

Rare earth elements (REEs) are a grouping of elements that encompasses lanthanides, yttrium and scandium due to their similar chemical properties and occurrence in ore deposits. Over the past few decades, economic interest in REEs has increased due to their use in several types of industries such as high-tech, medicine and agriculture. Extraction of REEs has been followed, in general, by incorrect disposal of tailing and waste, creating hazardous conditions in several countries. However, the magnitude of the possible impacts on ecosystem and human health are relatively unknown, especially in tropical systems. Thus, the objectives of this study were to assess the geochemical mobility and the bioaccessibility of REEs based on a series of chemical extractions and in vitro essay. We also tested two promising simple protocols (0.01 mol L-1 CaCl2 and 0.43 mol L-1 HNO3) for measuring REE bioaccessible fractions through a single extraction. Our findings show that the bioavailable fractions represent less than 20% of the ΣREEs fraction in all soil samples examine. Similarly, the oral bioaccessibility obtained by two in vitro methods (Gastric protocol and Gastric-Intestinal protocol) and by the single extraction tests represented less than 20% of the ΣREE contents. The non-carcinogenic risks and the carcinogenic risks associated to REEs oral exposure were low for children and adults. The extractions with 0.01 mol L-1 CaCl2 showed great potential as a method for measuring the REEs bioaccessible fraction.

The city of Manaus is the biggest industrial city of the north Brazilian region, and a haphazard urbanization process characterizes it. The continuous urbanization and industrialization processes have increased the levels of trace elements in the urban environment and have posed great threat on human health. It is, then, essential to assess the pollution levels and the potential risks of the trace elements presence in urban soils. Therefore, the purpose of this study was to investigate the status of trace elements soils pollution and their human health risks to the population of Manaus City. Twenty-two soil samples were collected from the surface layer (0-20 cm), and the contents of Ba, Cr, Mn, Zn, Co, Ni, Cu, Cd and Pb were analyzed. Results showed the predominance of kaolinite, gibbsite and goethite as the main minerals of the clay fraction. The trace elements contents were affected by both natural sources and anthropic activities such as industrial operations and vehicular emissions. The soil contamination assessment by Enrichment Factor showed the existence of eight samples classified as considerably contaminated and two samples classified as highly contaminated. Geoaccumulation index also showed the existence of eight samples exhibiting considerable contamination and one sample showing high contamination. The noncarcinogenic health risk was considered low (HI < 1) to both children and adults. However, the carcinogenic risk of Cd and Pb was higher than the safety limits (CRtotal> 1 x 10(-6)), indicating that the long exposure to contaminated soils increases the probability of children's cancer occurrence.

Amazonian soils have some physical, chemical and mineralogical differences, understanding the differences is important to understand the behavior of nutrients in the soil, especially phosphorus. The study was carried out in two types of soils: a Hydromorphic soil profile and a Non-hydromorphic soil profile in the Central Amazon region of Brazil, located in the metropolitan area of Manaus. Five depths were sampled: 0.00-0.05; 0.05-0.1; 0.1-0.2; 0.2-0.4; and 0.4-0.6 m. Physical, chemical, mineralogical and morphological attributes of both soils were studied. With the exception of clay, the levels of sand and silt remained stable in depth. The levels of organic matter gradually decrease in depth. The pH in water and in KCl, ∆pH, point of zero load, were similar between the surface and subsurface soils. Al3+, H++Al3+, CECt, CECT and clay activity were similar in Non-hydromorphic soil and increase in surface (< 0.2 m) and stabilize in subsurface (> 0.2 m). In both soils, the bases are reduced in subsurface (> 0.2 m). Aluminum and iron oxalate reduce with greater expressiveness in Non-hydromorphic soil. Aluminum and dithionite iron exhibit the same behavior. The levels of Goethite (Gt) and Hematite (Hm) are high in depth in the Non-hydromorphic soil and decrease in the Hydromorphic soil. There are sensitive distinctions between soils, due to the imposed edaphoclimatic conditions.

Durante algo mas de 50 anos antropologos, arqueologos, linguistas y geografos se han ocupado seriamente del pasado de la Amazonia. Mas recientemente otros academicos, entre ellos genetistas y ecologos, se han fascinado por el mismo. Durante mas de 10.000 anos los nativos han participado e interpretado esta historia. una historia que unos y otros leen y descifran a partir de diversas claves, como lo pueden ser las formas del paisaje, algunos objetos antiguos y los testimonios y tradiciones orales que tienen a su alcance. Los resultados son multiples. Estos revelan tanto desacuerdos entre los especialistas como mundos insospechados. Se hacen evidentes caminos que se cruzan y se mezclan; en una direccion convergen y en otra divergen. El lector encontrara en este volumen una fraccion de este universo, la misma va acompanada de una invitacion a participar en un dialogo amplio que contribuya a enriquecer nuestra vision de un mundo por explorar.

Manaus is the Capital City of Amazonas State, Brazil, in the heart of the Amazon rainforest. Its metropolitan area has a huge hydrographic basin where the disorganized urbanization has caused adverse effects in the urban rivers and creeks water quality. Thus, this study was conducted to evaluate the contents of Ba, Cr, Mn, Zn, Ni, Cu, the physicochemical parameters and their respective health risks in water samples from rivers and creeks located in urban areas with different degrees of urbanization in two different seasons. The determination of the physicochemical parameters showed the samples collected in areas with riparian vegetation presented mean values of temperature, pH, total dissolved solids and electrical conductivity lower than samples collected in urban environment. The hotspots of trace elements content were associated to the presence of industrial and domestic effluents as the main pollution source. The Water Quality Index results denoted a low water quality in four sampling sites, one during the rainy season and three others during the dry season. The overall non-carcinogenic health in the urban rivers was considered high in regions with huge population and intense anthropogenic activity. The results showed the potential risk of some of the trace elements on human beings, especially on children. The main element contributor to non-carcinogenic risk was Cr, although Mn and Ni also contributed to non-carcinogenic risk in a few areas, mainly for children during the dry season.

ABSTRACT Amazonian dark earths (ADEs) are fertile soils created by pre-Columbian Amerindian societies of the Amazon Basin. However, it is still not clear whether these soils were produced intentionally to improve infertile Amazonian upland soils or if they resulted from the accumulation of organic matter from sedentary settlements. This study characterizes the ADEs found in the naturally fertile alluvial floodplains of the Amazon River in the Central Brazilian Amazon according to total, exchangeable, and available contents of elements and organic carbon in soil profiles. ADEs contained higher levels of available elements and total P, Ca, Zn, and Cu. High total Cr, Ni, Co, and V content in these soils indicate that mafic minerals contributed to their composition, while higher contents of P, Zn, Ba, and Sr indicate anthropic enrichment. The presence of ADEs in floodplain areas strongly indicates non-intentional anthropic fertilization of the alluvial soils, which naturally contain levels of P, Ca, Zn, and Cu higher than those needed to cultivate common plants. The presence of archaeological sites in the floodplains also shows that pre-Columbian populations lived in these regions as well as on bluffs above the Amazon River.