ABSTRACT
RESUMO O Sistema Aquífero Guarani (SAG) compreende um dos mais importantes aquíferos do mundo, tanto pela grande reserva quanto pela qualidade de suas águas subterrâneas. Entretanto, nem todas as regiões, nas quais o SAG é utilizado no abastecimento público, possuem estudos a respeito do quimismo de suas águas e de sua associação com a geologia. Este trabalho apresenta a caracterização hidrogeoquímica das águas subterrâneas do SAG utilizadas no abastecimento público em São Carlos, São Paulo, região nordeste do SAG, por meio de amostras provenientes de 27 poços tubulares profundos. A captação de água subterrânea é proveniente principalmente do SAG. Entretanto, também é possível verificar a presença das formações Botucatu, Piramboia, Serra Geral, Itaqueri, Adamantina e sedimentos cenozoicos. Apesar de pouco mineralizadas, verifica-se variabilidade iônica na composição das águas subterrâneas, evidenciada na distribuição espacial da condutividade elétrica na área de estudo. Os resultados hidroquímicos apontam para a existência de quatro fácies hidroquímicas: bicarbonatadas mistas, bicarbonatadas cálcicas, bicarbonatadas sódicas e sódica fluoretada, em ordem decrescente de representatividade. A heterogeneidade geológica interfere na concentração de íons na água, por meio da dissolução mineral, e possibilita a mistura das águas subterrâneas. A análise de componentes principais constatou que 62,7% da variabilidade total do conjunto amostral é explicada, principalmente, por dois fatores. O primeiro grupo de variáveis representa 38,7% da variabilidade, atribuída principalmente aos íons provenientes da dissolução de minerais (HCO3−, Ca2+, Na+, Mg2+) e aos parâmetros relacionados a esse processo (pH e condutividade elétrica). O segundo revelou 24% da variabilidade total, que pode estar associado a origens antrópicas, como a presença dos íons Cl−, N-NO3−, SO42-, F− e K+.
ABSTRACT The Guarani Aquifer System (GAS) comprises one of the most important aquifers in the world due to its large water reserve and its groundwater quality. However, some regions that comprise the GAS groundwater for human supply are not thoroughly characterized on water chemistry and its relation with the local geology. This work presents the hydrogeochemical characterization of groundwater from the northeast region of the GAS used for human public supply in São Carlos (São Paulo, Brazil) based on samples from 27 deep boreholes. The groundwater exploration occurs mainly from GAS. However, it is also possible to verify the presence of the Botucatu, Piramboia, Serra Geral, Itaqueri, Adamantina, and Cenozoic sediments. Although little mineralized, there is a large ionic variability in the groundwater composition, also evidenced by spatial distribution of the electrical conductivity in the research area. These results explain four hydrochemical water types: mixed bicarbonate; calcium bicarbonate; sodium bicarbonate; and sodium fluoride, in decreasing order of representativeness. The concentration of ions in groundwater reflects the geological heterogeneity, through mineral dissolution and possible groundwater mixing. A Principal Component Analysis demonstrated that 62.7% of the total sample set variability is explained by two main factors. The first one represents 38.7% of the variability; mainly attributed to ions from minerals dissolution (HCO3−, Ca2+, Na+, Mg2+) and parameters related to this process (pH and electrical conductivity). The second group showed 24.0% of the total variability, which may be associated with anthropic activities origins, such as the presence of Cl−, N-NO3−, SO42-, F−, and K+.
ABSTRACT
Aim: To analyze samples of marine sediment at 24 stations for heavy metals as per sequential Community Bureau of Reference protocol in order to obtain metal distribution pattern in Kuwait offshore.Methodology: In the present study, a centrifugal particle-size analyzer was used for measuring sediment grain size. The Community Bureau of Reference scheme was deployed for the sequential extraction of heavy metal speciation, and the fractionation was determined by Inductively Coupled Plasma-Mass Spectrometry. Results: Grain-size analysis showed that the study area contained 71.8% silt, 22.6% sand and 5.56% clay at most locations. The average abundance of total concentration of heavy metals was found in the following order: lead< cobalt< copper< zinc< chromium< nickel. The mobility order of exchangeable fraction of heavy metals decreased in the order lead> nickel> zinc> cobalt> copper; in the reducible fraction: lead> copper> zinc> cobalt> nickel; in the oxidizable fraction: lead> chromium> copper> nickel> cobalt> zinc and in the residual fraction:cobalt> chromium> nickel> zinc> copper>lead, respectively. Interpretation: The outcome of the present study cannot establish the actual form of species of a given metal in the sediment; though, it appears to be useful in categorizing the metals within several prevailing geochemical fractions.
ABSTRACT
The relatively high abundance of geochemical elements such as Nb, Zr, Y and other elements shows serious interferences in the determination of trace silver in geochemical samples by inductively coupled plasma-mass spectrometry ( ICP-MS) . Thus it will lead to large deviation in the determination of geochemical samples without separation and enrichment. The traditional emission spectrum or graphite furnace atomic absorption method is only single-element analysis to the silver and with bad sample representativeness. In this study, load diphenylthiourea ( DPTU) foam selective enrichment was used for the separation of Au and Ag from other interfering elements in geological samples, and thiourea liberation-ICP-MS method was developed for the simultaneous determination of Au and Ag. The samples were first decomposed by 1:1 aqua regia. After addition of 50 mL of water, the samples were adsorbed under oscillation for 30 min at 20℃. The detection limits of the Au and Ag were 0. 02 ng/g and 0. 007μg/g, respectively. The proposed method was successfully applied to the determination of Au and Ag in eight national standard materials.
ABSTRACT
Este estudo foi desenvolvido na Plataforma Continental do Amazonas (PCA) com o objetivo de determinar os níveis de Hg total no sedimento de fundo, e assim contribuir como matriz ambiental indicadora para o plano geral de gerenciamento costeiro na região norte do Brasil. Foram amostrados 20 pontos entre maio e junho dos anos de 1999 a 2002, 2005 e 2007. Os resultados indicam não haver evidências de atividades antrópicas relacionadas à contaminação de mercúrio na região. Os teores encontrados variaram entre 0,047 e 0,166 mg kg-1 com média 0,085±0,026 mg kg-1, estando dentro do intervalo de "background" referido para os rios amazônicos não contaminados, que é de 0,05 a 0,28 mg kg-1. As concentrações de Hg no sedimento, especialmente no sedimento lamoso, mostraram uma estreita dependência com os teores de argila (material fino) e matéria orgânica, corroborando mecanismos geoquímicos importantes na dinâmica do metal. A maior adsorção do mercúrio pode estar associada ao aumento dos teores de compostos (óxidos e hidróxidos) de ferro, alumínio, manganês e os minerais primários e secundários formadores das rochas da bacia de drenagem amazônica.
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.
Subject(s)
Butterflies , RainforestABSTRACT
There is a severe fluoride problem in Nawa tehsil of Nagaur district. Villagers are suffering from dental fluorosis and skeletal fluorosis. So an extensive geochemical study of 27 villages of eastern, south-eastern and southern zone of Nawa tehsil was done. Total 46 ground water samples were collected and analyzed for various physicochemical parameters as well as fluoride content. The ground water samples collected in clean polyethylene plastic containers were analyzed for pH, electrical conductivity, total dissolved salts, calcium, magnesium, total hardness, chloride and alkalinity. The fluoride concentration in the three different zones ranged from 0.64 to 14.62 mg l-1 where 13.04% samples were found within permissible limit while 86.96% had fluoride beyond permissible limit (> 1.5 mg l-1). It was found that among the three different zones south-eastern zone was under serious fluoride contamination where fluoride concentration ranged between 1.10 to 14.62 mg l-1. In the eastern zone fluoride concentration was recorded from 1.52 to 5.13 mg l-1 whereas in the southern zone it was found between 0.64 to 3.63 mg l-1.
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Heavy metal distribution in superficial sedimenta ta Saco, Gulf of Cariaco, Sucre, Venezuela. The Gulf of Cariaco is a marine ecosystem with high primary productivity, which gives it an ecological and socioeconomic importance. Nevertheless, anthropogenic activities around the Gulf produce wastes that are deposited directly or by runoff into the sediments, and consequently, increases concentrations of metals in this ecosystem. The objective of this study was to determine the distribution of cadmium, copper, lead, manganese, nickel and zinc in geochemical fractions of surface sediments, using modified BCR sequential extraction procedure. The concentrations were measured using flame atomic absorption spectroscopy. In addition, the contents of soluble and exchangeable metals associated to carbonate fractions, determined by BCR, were compared with those determined by the method of Campanella. Samples were collected in 12 stations during June 2007. The applied methodologies were evaluated with a certified reference material of marine sediments (HISS-1) and the results indicated that these methods provide adequate accuracy and precision for the extraction of metals. The total metal concentrations (μg g-1) were, Cd: < limit of detection (LD)-5.0; Pb: 1.79-60.41; Cu: no detected (ND)-42.18; Zn: 25.13-104.57; Mn: 66.31-80.29 and Ni: 3.29-24.58. Cd, Cu, Ni and Pb at several stations, exceeded the Canadian Sediment Quality Guidelines of the Lowest Effect Levels (LEL). Cadmium was identified as being the most mobile of the elements, having the highest concentrations in soluble and exchangeable cations and carbonates. However, Pb, Cu, Mn and Zn levels were found highly associated to organic matter and sulfide fractions. The methods did not show significant statistical differences for the extraction of soluble and exchangeable cations and the metals associated to carbonate fraction. There are several significant correlations between heavy metals, which suggest their common origin. Rev. Biol. Trop. 58 (Suppl. 3): 129-140. Epub 2010 October 01.
El Golfo de Cariaco es un ecosistema marino con mucha productividad primaria, lo que le confiere especial importancia ecológica y socioeconómica. Sin embargo, los desechos de las actividades antropogénicas son descargados directamente o arrastradas por las escorrentías. El objetivo de este estudio fue determinar la distribución de cadmio, cobre, plomo, manganeso, níquel y zinc en las fracciones geoquímica de los sedimentos superficiales, usando el método modificado de extracción secuencial de la Comunidad Europea (BCR). Las concentraciones de los metales fueron medidas por espectroscopía de absorción atómica. Además, se compararon los contenidos de metales intercambiables y asociados a los carbonatos determinados por el procedimiento BCR modificado con los determinados por el método de Campanella. La recolección de muestras se hizo en 12 estaciones del sector oriental del Golfo de Cariaco, Estado Sucre, específicamente en el sector conocido como el Saco, en junio 2007. Las metodologías aplicadas fueron evaluadas usando un material de referencia certificado de sedimentos marino (HISS - 1). Los resultados indicaron que los métodos proveen exactitud y precisión adecuadas para la extracción de metales. Las concentraciones totales (μg g-1) fueron, Cd: < límite de detección (LD)-5.0; Pb: 1.79- 60.41; Cu: no detectado (ND)-42.18; Zn: 25.13-104.57; Mn: 66.31-80.29 y Ni: 3.29-24.58. Cd, Cu, Ni y Pb excedieron en varias estaciones los límites que pueden afectar la biota, establecidos por la Guía de Evaluación de la Calidad de los Sedimentos de Canadá. El cadmio fue el metal identificado como el más móvil, teniendo las más altas concentraciones como intercambiable y asociado a las fracciones de carbonatos. Sin embargo, Pb, Cu, Mn y Zn mostraron su mayor abundancia en la fracción asociada a materia orgánica y azufre. Los métodos no presentan diferencias significativas para extraer la primera fracción. Se encontraron significantes correlaciones entre los metales pesados que sugieren su origen común.
Subject(s)
Environmental Monitoring/methods , Geologic Sediments/chemistry , Metals, Heavy/analysis , Water Pollutants, Chemical/analysis , VenezuelaABSTRACT
A biorremediação natural da água subterrânea contaminada com óleo diesel em um posto de combustíveis foi avaliada mediante o monitoramento de indicadores geoquímicos e ensaios laboratoriais de biodegradação. Durante um período de dois anos foram realizadas quatro coletas de água subterrânea para a avaliação de diversos parâmetros físico-químicos e a concentração de hidrocarbonetos. As análises microbiológicas consistiram na contagem de bactérias heterotróficas totais, na verificação da presença de bactérias hidrocarbonoclásticas e no teste de biodegradabilidade utilizando o indicador redox DCPIP. Foi possível identificar fatores que corroboram o emprego da técnica de biorremediação natural para o tratamento da água subterrânea, contudo, a presença de hidrocarbonetos retidos no solo representa uma fonte contínua de contaminação, por isso se faz necessário o monitoramento a longo prazo.
The natural bioremediation of the groundwater contaminated with diesel oil at a petrol station was evaluated by monitoring geochemical indicators and biodegradation tests in laboratory. During two years the groundwater was collected four times. Different physic-chemical parameters and the concentration of hydrocarbons were evaluated. Microbiological analyses consisted of total heterotrophic bacteria counting, verification of the presence of hydrocarbonoclastic bacteria and the biodegradability test using the redox indicator DCPIP. It was possible to identify factors that confirm the use of the natural bioremediation technique as a treatment to the groundwater, however, hydrocarbons retained in the soil represent a continuous source of contamination, and for this reason, a long term monitoring is necessary.
Subject(s)
Groundwater , Biodegradation, Environmental , Filling Station , Fuel Oils , Pollution IndicatorsABSTRACT
The concentrations of Cr, Mn, Fe, Co, Ni, Cu, Zn, and Pb in the main geochemi-cal phases of the sediment (exchangeable, bound to organic matter, bound to Fe-Mn oxides, and residual) were studied in the bottom sediments of the Guamá river and the drainage channels (Tamandaré, Quintino, Reduto, and Una) of Belém, Pará. The concentrations of metals in the bottom sediments of the Guamá river showed to be associated mainly to residual phase, whereas in the channels they are linked to Fe-Mn oxides and residual phase. Generally, in the analized sediments, the groups of metals Fe, Zn, Pb are showing association with the Fe-Mn oxides phase, and Cu, Cr, Mn, Co, Ni with residual phase.
As concentrações de Cr, Mn, Fe, Co, Ni, Cu, Zn e Pb nas diferentes fases do ambiente sedimentar (trocável, orgânica, redutível e residual) são analisadas nos sedimentos de fundo dos canais de drenagem mais importantes de Belém - Quintino, Tamandaré, Reduto e Una - e no rio Guamá. Os resultados mostram que a maioria dos metais associa-se preferencialmente à fase residual no rio Guamá e às fases redutível e residual, no caso dos canais. De um modo geral, os metais Fe, Zn e Pb se associam geralmente à fração redutível, enquanto Cu, Cr, Mn, Co e Ni mostram-se relacionados à fração residual.