Navegando por Autor "SIQUEIRA, Gilmar Wanzeller"

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Acesso aberto (Open Access)
Avaliação de risco ambiental por contaminação metálica e material orgânico em sedimentos da bacia do Rio Aurá, Região Metropolitana de Belém - PA
(Instituto Nacional de Pesquisas da Amazônia, 2013-03) SIQUEIRA, Gilmar Wanzeller; APRILE, Fábio Marques
The Aurá River basin is situated in the Belém Metropolitan region, between the municipalities of Belém and Ananindeua, where the rate of population growth has increased without any social and environmental control. The region is intensely exploited and the more frequent environmental problems are deforestation, erosion, flooding, water pollution and contamination, especially by heavy metals and organic compounds (OC). Geochemistry behavior (Al, Fe, Mn, Cr, Ni and Cu) and OC levels were determined in the 30 sampling sites between 2008 and 2010 in the bottom sediments of the river. There is an uncontrolled sanitary landfill situated at the north of the Aurá River responsible, in part, by the metallic contamination of the sediments. The environmental stress is classic in the region, and it has resulted from anthropic activities, which has transported unconsolidated material associated to metals to the Aurá. The variables studied were classified on the transport mechanisms and sources (allochthonous and/or autochthonous). The results showed that the main contribution of ions Al and Fe was the sanitary landfill; Mn and Ni was the adjacent soils; Cr was modified (III/VI) by the allobiochemistry, and Cu by bio-induced processes.
Acesso aberto (Open Access)
Determinação dos elementos-traço (Zn, Co e Ni) em sedimentos da Plataforma Continental Amazônica sob influência da descarga do rio Amazonas
(Instituto Nacional de Pesquisas da Amazônia, 2006) SIQUEIRA, Gilmar Wanzeller; PEREIRA, Simone de Fátima Pinheiro; APRILE, Fábio Marques
Determination of trace elements (Zn, Co and Ni) in sediments at the Amazon Continental Shelf on influence of the Amazon River discharge This research was developed at Amazon Continental Shelf (ACS) between the Orange Cape (Amapá State) and the Maguari Cape (Pará State), to determine the levels of zinc, cobalt and nickel in the superficial sediments identifying its inputs and outputs. The rate of these metallic elements in the sediments decreases following Zn> Ni> Co. The concentrations of total metals in the surface sediments range from Zn = 52.8 159.5; Ni = 21.7 47.4 and Co = 14.3 48.8 (mg.kg-1). The levels of trace elements observed in the sediments at ACS are of natural occurrence. Pollution sources of metallic elements were not observed.
Acesso aberto (Open Access)
Diagnóstico da qualidade da água do rio Parauapebas (Pará - Brasil)
(Instituto Nacional de Pesquisas da Amazônia, 2012-09) SIQUEIRA, Gilmar Wanzeller; APRILE, Fábio Marques; MIGUÉIS, Antonio Miguel Borregana
The objective of this research was to develop a diagnostic of the water quality of the Parauapebas River (Pará, Brazil), in the dry periods of 2004, 2007 and 2009. In 20 sampling sites in Parauapebas River, around of the Parauapebas City, physical (transparency, water temperature and total solid residues), chemical (dissolved oxygen, pH, turbidity, alkalinity, hardness, acidity, chloride, Biochemical Oxygen Demand, Chemical Oxygen Demand, total phosphorus, total iron and total nitrogen), and biological parameters (thermotolerant coliforms) were measured. The results were used for the determination of Water Quality Index (WQI). As support to the interpretation of these parameters, a Principal Components Analysis (PCA), multiple regression and linear regression analyses and, a general survey of physical, biotical and social-economic of the region were performed. WQI for the Parauapebas River, in the monitored area, was 40.01, which classifies it in the category "Regular". The PCA and multiple regression analysis identified four parameters that have been employed in the WQI determination and that influenced significantly the variation of the Index: dissolved oxygen, BOD, total phosphorus and thermotolerant coliforms, which explained 75% of the variation of the results. The results indicate that the urban expansion, in especial in the directions N-NW and S-SW, has reached the areas surrounding the Riparian Forest, and affected partially the surface water quality of the Parauapebas River.
Acesso aberto (Open Access)
Distribuição de mercúrio total em sedimentos da plataforma continental Amazônica: Brasil
(Instituto Nacional de Pesquisas da Amazônia, 2012-06) SIQUEIRA, Gilmar Wanzeller; APRILE, Fábio Marques
This study was developed at the Amazon Continental Shelf aims to determine the levels of total mercury in the sediment bottom, and them to contribute as environmental matrix for the general plan of coastal monitoring in the North Region of the Brazil. Twenty sampling sites between May and June from 1999 to 2002, 2005 and 2007 were analyzed. The results indicate there is not evidence of anthropic activities associated to the contamination by mercury in the region. The levels of total mercury founded range between 0.047 and 0.166 mg kg-1 with average of 0.085±0,026 mg kg-1. The results are inside of the background interval determined to not contaminated or not polluted Amazon Rivers, which the interval ranges from 0.05 to 0.28 mg kg-1. The mercury concentrations in the sediment bottom, especially in the mud sediment, had shown a narrow dependence with both the clay levels (fine material) and organic matter, corroborating important geochemical mechanisms in Hg dynamics. The largest adsorption of the mercury can be associated to the increase of the oxides and hydroxides compounds of iron, aluminum, manganese and others primary and secondary minerals from the rocks of the Amazon drainage basin.
Acesso aberto (Open Access)
Distribuição do mercúrio em sedimentos de fundo no Estuário de Santos SP/Brasil
(2005-12) SIQUEIRA, Gilmar Wanzeller; BRAGA, Elisabete de Santis; PEREIRA, Simone de Fátima Pinheiro; SILVA, Elisamar da
Bottom sediment samples were collected and analyzed for mercury in the Estuary of Santos-SP. The analytical results reveal anthropogenic contamination for some sectors of this estuarine area as a result of petrochemical and metallurgical residues derived from the Industrial District of Cubatão, from the activities of the State of São Paulo Siderurgy (COSIPA), from the Santos harbor and, finally, from effluents discharged by the submarine emissary into the Bay of Santos. The values for the factor of contamination (FC) found in the bottom sediments range from 1 to 3, mainly for the channels of Santos and São Vicente; however, in the Bay of Santos the FC values (below 1) indicate low contamination except in the discharge area of the submarine emissary.
Acesso aberto (Open Access)
Hydrogeological Characteristic and the Vulnerability Degree of the Aquifers from Municipality of Abaetetuba, Pará - Brazil
(Universidade Federal do Pará, 2019-03) LEITE, Andreza Cristina Morais; SIQUEIRA, Gilmar Wanzeller; DARWICH, Assad José; APRILE, Fábio Marques
This study evaluated the quality of groundwater in the municipality of Abaetetuba (PA, Brazil 1°43'46'' S e 48°52'27'' W) based on the hydrogeological characterization and degree of vulnerability of the aquifer system. The municipality of Abaetetuba is practically all supplied by groundwater both by deep tubular wells and shallow pit wells (Amazonian wells), which present potential risk of contamination. Water and soils samples from 20 wells sampled between 2012 and 2016 were used. Physicochemical and microbiological analyzes served as a data base for mapping (GIS). Three hydrogeological domains were identified within the study area: Barreiras Group (predominant), Post-Barrier Sediments and Recent Sediments. Almost all of the samples presented microbiological levels above the MPV defined by the Brazilian legislation for water intended for human consumption. The DRASTIC and GOD vulnerability indexes presented values between 75 and 119 and 0.15 and 0.32 respectively, suggesting areas of 'low' to 'moderately-high' vulnerability. Local sources of pollution by coliforms have been identified due to lack of basic sanitation. Evidence of diffuse sources derived from vehicle washing and lubrication also have been identified. Although the Barreiras Group had deep semi-confined aquifers, a 'state of alert' was suggested for the areas that indicated the presence of fecal coliforms and with a high population density. Isovalues and vulnerability maps suggest areas that require further monitoring. A positive correlation between the DRASTIC Index and TDS in well water was established. The intense exploitation of groundwater especially in areas of great population density may be causing contamination of aquifers.
Acesso aberto (Open Access)
Sedimentary transport influences on diagenetic processes at the Amazon continental shelf, Brazil
(SCIENCEDOMAIN International, 2019) APRILE, Fábio Marques; SIQUEIRA, Gilmar Wanzeller; DARWICH, Assad José; IRION, Georg Friedrich
This research aimed to correlate the sedimentary transport with the diagenetic processes in the coastal zone and Amazon Continental Shelf (ACS). Physical and physical-chemical parameters, trace element contents (Cr, Pb, Ni, Zn and Hg), and O2, CO2 and iron flux were determined in sediment and pore water. Sedimentary incubation (96 hours) and algorithms were applied to determine the variation of the activity coefficient (ΔI) and ionic strength (Fi) of the predominant chemical species, and to estimate the net production and mineralization of the organic matter (ΔCO2T) in the system. There are not many studies applying incubation tests to identify the diagenetic processes, especially in fluvial-marines sediments. The results showed a strong zonation associated to the transport and deposition processes, influenced mainly by the grain-size and texture of sediment and fluvial streams. The distribution of trace elements followed the trend of the sedimentary pattern, with higher levels of metals in the deposits of clay minerals and organic matter. A factor of weight (Fw), calculated to establish the degree of importance of each parameter under the distribution and mobility of trace elements, suggests that the mobility of Cr, Ni and Zn is controlled by depth, clay and organic compounds contents, and concentration of dissolved oxygen.The vertical flow of O2 and CO2 and the Fe2+/Fe3+ ratio in the pore water suggest a predominance of organic matter oxidation in the sedimentary layer between 0.0 and 0.2 m, with partially anaerobic mineralization of the sediments below 0.4 m. Increases in trace element concentrations were observed in iron reduction zones, indicating processes of desorption of oxides and hydroxides of Fe and mineralization of organic matter. The extrapolation of the results of the incubation test to the studied system allowed to establish three hypotheses related to the diagenetic processes: 1) the flow of marine currents may be allowing the aerobic oxidation in the sandy sediments, with the nitrification route more accentuated than the ammonification route; 2) in the region of the coastal zone and inner continental shelf the routes of oxidation and reduction may be alternating according to the physical-chemical factors and seasonality; 3) in the coastal zone and inner shelf the net mineralization rate exceeded the net production rate of the organic matter (ΔCO2T >0).