Ronaldo de Almeida

Federal University of Rondônia | unir · Departamento de Química

This paper reports the results of a mercury (Hg) and selenium (Se) metallomic study in the liver tissues of Psectrogaster amazonica and Raphiodon vulpinus from the Brazilian Amazon. Two-dimensional electrophoresis, graphite furnace atomic absorption spectrometry, and liquid chromatography-tandem mass spectrometry were performed. Hg and Se determina...

O objetivo com este trabalho foi avaliar a qualidade física de um Latossolo Vermelho-Amarelo submetido a diferentes estados de compactação, e sua relação com o sistema radicular e a produtividade de gramíneas forrageiras. O experimento foi instalado na Universidade Federal de Rondônia – UNIR no ano de 2018. O delineamento experimental utilizado foi...

Mercury (Hg) is a chemical element that poses risks to human health due to its high toxicity and environmental persistence. We determined the total Hg (THg) and methyl Hg (MeHg) concentrations in hair samples from residents of the Demarcação District (Porto Velho, Rondônia) in the Brazilian Amazon, as well as in water and fish samples, to evaluate...

This study presents a 35-year record of total mercury (Hg) concentrations in the detritivore fish Prochilodus nigricans (Curimatã) and the carnivore Cichla pleiozona (Tucunaré), two of the most widely distributed, ecologically important and consumed fish species in the upper Madeira River Basin in the Western Brazilian Amazon. Fish samples from the...

Inundações afetam centenas de famílias nos bairros atingidos pelas águas do Rio Pirarara na área urbana do munícipio de Cacoal – RO. O objetivo da pesquisa foi a analisar a morfometria, desmatamento e identificação de áreas suscetíveis a inundação. A análise morfométrica foi realizada pelo processamento de dados vetoriais e matriciais com Software...

A gestão eficiente dos recursos hídricos em plantações é uma preocupação crescente mundial para garantir a sua sustentabilidade. Estudos apontam que 70% da água captada no mundo é utilizada na irrigação e que a irrigação em excesso pode chegar até 40%. Soluções tecnológicas de ponta e alto custo estão disponíveis para monitorar e otimizar o uso da...

The isotopic signatures of carbon in primary consumer fish species in the Madeira River basin (Western Amazon) follow a pattern, with basal species feeding mainly on C 3 (e.g., vascular plants and phytoplankton). In this study with 196 specimens of 19 fish species and six trophic guilds, significant differences were found between the two main group...

RESUMO O sistema agroflorestal (SAF) é o uso da terra que integra no mesmo espaço o cultivo de espécies agrícolas e silviculturais. O SAF é estratégico na mitigação das emissões do dióxido de carbono (CO2), causado pela mudança no uso e cobertura da terra. O estudo teve o objetivo de quantificar os estoques de carbono orgânico do solo (ECS) em dife...

An extensive fleet of rafts and dredges to extract sediments from the Madeira River looking for gold has reignited the debate about mining in the Amazon and the inevitable Hg contamination. The mining legislation in Brazil presupposes that miners are poor men with rudimentary implements, which does not jibe with what is happening today in the Amazo...

Este trabalho versa contribuições de uma sequência didática desenvolvida com a turma de alunos do curso Técnico Profissionalizante em Enfermagem na forma Subsequente em uma instituição de ensino pública, ao se constatar a necessidade da superação do pensamento tecnicista, onde os alunos apesar de identificarem impactos diretos aos indivíduos em dec...

Cr contamination is a growing concern in the Amazon. Along with the rise of cattle farming in the region, tanneries are becoming more common and threatening environmental quality, since the effluents from this activity are rich in Cr. The objective of this study was to evaluate the seasonal and spatial dynamics of Cr in fish with different feeding...

The Machado River is the main tributary of the Madeira River in the state of Rondônia, a region that has been impacted by deforestation, livestock, urban development, alluvial gold mining and urban and industrial effluents that likely contribute to the introduction of mercury (Hg) in the aquatic system. We aimed to determine the concentrations of t...

In the Amazon, mercury (Hg) contamination comes from ASGM operations along with soil remobilization processes associated with deforestation. The objective of this study was to evaluate the exposure to methylmercury (MeHg) and total mercury (THg) in 88 samples of skin and blubber tissue obtained from live captured river dolphins (Inia boliviensis, I...

Background The Madeira River (Amazon Basin) has been impacted by activities related to artisanal and small-scale gold mining (ASGM), deforestation and burning (for timber, agriculture, and hydroelectric dam projects). All these activities contribute to environmental mercury (Hg) release and cycling into the Amazon ecosystem and thus to changing lif...

The energy transfer in the aquatic food chain is an important way for mercury (Hg) to enter other trophic levels. The objective of this work was to evaluate the Hg concentrations in plankton upstream and downstream of the Samuel Hydroelectric Reservoir, Rondônia, Brazil. Phytoplankton and zooplankton samples were collected with 20-μm and 68-μm nylo...

The energy transfer in the aquatic food chain is an important way for mercury (Hg) to enter other trophic levels. The objective of this work was to evaluate the Hg concentrations in plankton upstream and downstream of the Samuel Hydroelectric Reservoir, Rondônia, Brazil. Phytoplankton and zooplankton samples were collected with 20-μm and 68-μm nylo...

The term land-use describes the different forms land is employed and occupied. In rural environments, an agroforestry system (AFS) is any land-use method that is a source of income and food to households and can help reduce anthropogenic carbon emissions to the soil caused by change in land-use. This study analyzed the spatial variability of organi...

The impact of a hydroelectric run-of-river (RoR) dam construction on the dynamics of total mercury (THg) and methylmercury (MeHg) is of interest to the environment and health of human and wild life. We monitored (May 2010 to October 2018) THg and MeHg in the waters and in the suspended particulate matter (SPM) of the Madeira River and its tributari...

An agroforestry system (AFS) describes the conjoint use of land for agricultural andforestry purposes. An AFS plays a strategic role in the mitigation of carbon dioxide(CO2) emissions, and stands as an alternative in land use that reduces mercury (Hg)remobilization in cultivated soils. This study evaluated the spatial variability of Hgconcentration...

The studies on metals in Madeira River's principal flow show high variability of Co, Cr, Cu, Fe, Ni, Pb and Zn concentrations. However, the transfer of these metals from the main river channel, whose physical and chemical characteristics differ from those of lakes, has not been fully characterized. The objective of this study was to discuss how the...

The gold mining in the Madeira River basin is performed by dredges and ferries that extract from the bottom of the river alluvial gold which is amalgamated with mercury (Hg). Throughout the process of gold purification, the Hg can be recovered by retort or crucible distillation. Subsequently, the gold is taken to the city of Porto Velho for commerc...

The studies on metals in Madeira River’s principal flow show high variability of Co, Cr, Cu, Fe, Ni, Pb and Zn concentrations. However, the transfer of these metals from the main river channel, whose physical and chemical characteristics differ from those of lakes, has not been fully characterized. The objective of this study was to discuss how the...

Total mercury (THg) concentrations measured in two freshwater shrimp species (Macrobrachium depressimanum and Macrobrachium jelskii) showed a relationship with the location of artisanal and small-scale gold mining (ASGM) from the Madeira River Basin, Western Amazon. Between August 2009 and May 2010, 212 shrimp samples were collected in the confluen...

The present study assesses mercury biomagnification and the trophic structure of the ichthyofauna from the Puruzinho Lake, Brazilian Amazon. In addition to mercury determination, the investigation comprised the calculation of Trophic Magnification Factor (TMF) and Trophic Magnification Slope (TMS), through the measurements of stable isotopes of car...

This study was conducted in the Western Amazon, in an area located on the campus of the Federal University of Rondônia in Porto Velho, Rondônia. Were analyzed in soil samples of mercury (Hg) and organic matter (OM) concentrations in a stretch of open rain forest. The average Hg concentration was 150 ± 28g.kg-1, whereas the concentration of OM was...

As dificuldades na produção de organismos zooplanctônicos em larga escala estão relacionadas à falta de conhecimento suficiente para produção massiva e constante destes organismos. Este trabalho propôs descrever o crescimento populacional de Moina sp. em sistema de cultivo estático, visando subsidiar a elaboração de protocolo de produção. Cem organ...

Knowing the mercury levels of an environment allows a diverse array of biogeochemical studies into the mercury cycle on a local or global scale. Among matrices commonly evaluated, water remains a challenge for research because its mercury levels can be very low, requiring development of complex analytical protocols. Currently, sample preservation m...

This study was conducted in the Western Amazon, in an area located on the campus of the Federal University of Rondônia in Porto Velho, Rondônia. Were analyzed in soil samples of mercury (Hg) and organic matter (OM) concentrations in a stretch of open rain forest. The average Hg concentration was 150 ± 28□g.kg-1, whereas the concentration of OM was...

O cubiu (Solanum sessiliflorum Dunal) (Solanaceae) é originário da região Amazônica. Suas propriedades alimentares, medicinais e agronômicas têm despertado o interesse de pesquisadores desde 1970. No entanto, estudos sobre insetos em plantas tanto de ocorrência natural como de cultivos são escassos. O objetivo deste trabalho foi realizar um levanta...

The study was conducted in Puruzinho lake (Humaitá, AM) considering seasonal periods of rainy and dry in way to elucidate the flood pulse importance in the deposition, remobilization and distributions of mercury and organic matter in bottom sediments in the Madeira River Basin (Brazilian Amazon). Bottom sediments and soils samples were analyzed for...

In the present study, we investigated the mercury distribution, mercury bioaccumulation, and oxidative parameters in the Neotropical fish Hoplias malabaricus after trophic exposure. Forty-three individuals were distributed into three groups (two exposed and one control) and trophically exposed to fourteen doses of methylmercury each 5 days, totaliz...

High fish consumption and extended breastfeeding are hallmarks of traditional lifestyle in Western Amazonia. We studied sources of mercury exposure, fish-methylmercury (meHg) and dental-amalgam filling, in 75 urban and 82 rural lactating mothers. Total mercury was determined in all samples while meHg concentrations were determined in subsamples of...

Top marine predators present high mercury concentrations in their tissues as consequence of biomagnification of the most toxic form of this metal, methylmercury (MeHg). The present study concerns mercury accumulation by Guiana dolphins (Sotalia guianensis), highlighting the selenium-mediated methylmercury detoxification process. Liver samples from...

Distribution of Hg along soil profiles from the Madeira River Basin between Porto Velho-RO and the mouth at the Amazon River, showed the highest concentrations varying with soil horizons depending on texture and organic matter content of a given layer. Highest Hg concentrations were found in clay soils, being influenced by soil type.

In order to investigate the potential risk of mercury and DDTs exposure to fish-eating human populations in Samuel Reservoir, not affected directly by gold-mining activities, the axial muscle of Cichla monoculus was analyzed. Twenty-nine and thirty adults individuals were collected respectively on February (rainy season) and August (dry season) 200...

Methylmercury (MeHg) arouses great interest, since it is a neurotoxin and has a tendency to bioaccumulate and biomagnified to become a risk to human health. This study aimed to evaluate methylmercury concentration and its percentage relative to total mercury in muscle tissue of fish collected in the Madeira River Basin in the Amazon region.

Subsistence ribeirinhos of the Amazon Basin depend on fish for their principal source of protein, but fish availability changes with seasonal high and low waters. To assess taxa and quantity of fish consumed and estimate attendant exposure to methyl-Hg in a traditional subsistence high fish-eating community of the Amazon Basin. 120 villagers in 18...

The Brazilian Amazon region has some of the main mineral reserves of the world. Since the seventies’ decade many of them have been explored by miners and artezan that base their survival source on this activity. The cassiterite mining in the western Brazilian Amazon is one of the big-scale mining with some communities living around and nearby the a...

Background: Subsistence ribeirinhos of the Amazon Basin depend on fish for their principal source of protein, but fish availability changes with seasonal high and low waters. Aim: To assess taxa and quantity of fish consumed and estimate attendant exposure to methyl-Hg in a traditional subsistence high fish-eating community of the Amazon Basin. Subject...

Natural and anthropogenic factors contribute to the increase in suspension sol- ids production in the Madeira River basin, being trace elements the main substances carried in suspension. Among these elements Hg is one representing greater risk to human health. This study on the high Madeira River basin investigate the seasonal variation of suspende...

Vários estudos têm sido desenvolvidos nos últimos 20 anos na bacia do Rio Madeira (Amazônia) com o objetivo de diagnosticar a presença de mercúrio em peixes e compreender o ciclo deste elemento no meio ambiente tropical. Neste artigo são discutidas tendências temporais na concentração de Hg e sua relação com a massa corporal de algumas espécies de...

Over the last 20 years several projects carried on the Madeira River basin in the Amazon produced a great amount data on total Hg concentration in different fish species. In this paper we discuss temporal trends in Hg contamination and its relation to body weight in some of those fishes, showing that even within similar groups, such as carnivorous...

O correto aproveitamento dos recursos naturais deve ser feito após criteriosas análises que certifique tal exploração. Este resumo mostra como a análise multivariada justificou a potencialidade do uso de indivíduos de babaçus encontrados em bioma amazônico para fins energéticos.

Regular annual flooding of the Amazonian rivers changes the aquatic environment affecting fish feeding strategies. The Rio Madeira has been greatly impacted by deforestation for agricultural projects, damming for a hydroelectric power plant, and alluvial gold extraction. We studied fish-Hg concentrations within defined weight ranges of representati...

This study has the objective of evaluating the total mercury concentrations (Hg) in plankton samples of Puruzinho Lake, which is located on the left margin of the Madeira River, 20 km downstream of the Humaitá city (Amazon state, Brazil). Three samples were taken at a central part of the lake (S07°22’19.2”; W063°02’32.2”) during rainy (February 200...

This work uses the geostatistical method for mercury and organic matter spatial modeling in lakes systems. It uses the indicative kriging to elaborate probabilities maps of mercury and organic matter concentration in sediment. The fitting model so much to mercury how to organic matter was the gausian model. The geostatistic was a effective tool in...

storage tanks (UST) are widely used in the Porto Velho area. A large number of these USTs are in bad condition due to corrosion processes causing groundwater contamination. A large number of these leaking underground fuel tanks (LUFT) are in urban areas but due to the lack of water quality monitoring, they are only detected when there is a high con...

Underground storage tanks (UST) are widely used in the Porto Velho area. A large number of these USTs are in bad condition due to corrosion processes causing groundwater contamination. A large number of these leaking underground fuel tanks (LUFT) are in urban areas but due to the lack of water quality monitoring, they are only detected when there i...

Spatial distribution of mercury concentration in suspension solids of the upper Madeira river, Rondonia The main goal of this work was going to study the spatial distribution of mercury in suspension solid in the upper Ma-deira river, comprehended between its formation by Beni and Mamore rivers until Porto Velho’s city, using geostatistical analysi...

This work presents quality control results on the mercury concentrations in different environmental (river sediments, forest soils, river suspended matter and fish) and human samples from the lower Madeira River, Amazon sampled between 2001 and 2003, about 15-20 years after the nearly cessation of gold mining activities in the region, which reached...

The present work evaluates the Hg concentrations in the planktonic community of the Samuel hydroelectric reservoir (Amazon/Brazil). Plankton samples were collected from September 2003 to May 2004, to verify possible correlations with the variation in the water level in the reservoir. Plankton samples were collected through two nylon nets, one with...

This paper reports a study concerning the dating of a sediment core collected at Lago Puruzinho, Amazônia Ocidental -Brazil where a Hg contamination was found. This lake is located at the left margin of Madeira river, 20 km far from Humaitá city, Amazonas state. The sediment core was collected in 2006 and analysed by Pb-210 method. The age of sedim...

The presence of mercury in several compartments of the aquatic ecosystems represents a problem of great concern in the Amazonian basin. The goal of this work is to correlate the amount mercury found in bottom sediment with other trace elements as well as its spatial distribution in the upper Madeira River. Field samples were acquired on February of...