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Hydraulic characterization of aquifer systems is important for the development of exploitation scenarios and groundwater management strategies. Especially in lithologically heterogeneous aquifers, local scale variations in transmissivity (T) may not be neglected. Field scale transmissivity values are usually derived from pumping tests, but in most cases their number and availability are rather limited. Thus, direct measurement of transmissivity over an entire aquifer is expensive and technically almost impossible. In such situations, inverse hydrodynamic modelling is the appropriate solution. In this article, the real transmissivity field of the aquifer of the Continental Terminal of Abidjan is investigated by a multi-scale parametrization that allows to bypass the problem of scale change and to determine this hydrodynamic parameter over the entire aquifer. This hydrogeological modelling of the Continental Terminal aquifer identified a structure of 153 nodes in size as the closest structure to that of the Continental Terminal aquifer. The transmissivity field associated with this optimal size, ranging from 5.4.10-5 to 1 m2s-1, has been compared with values published in other studies in Africa and the world. These identified values are plausible and have a good overall structure. The success of this modeling is strongly linked to the quantity, quality and spatial distribution of authentic informations on the parameters sought.
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Knowledge of flow exchange between surface and groundwater is of great importance for use of water resources. The determination of seepage between a stream and an underlying aquifer requires an accurate estimation of the river stage and of the head in the aquifer. An approach is presented to estimate analytically river flow and stage while using the SAFE conductance to calculate the seepage. A major contribution of this article lies in the methodology for river routing with its use of a modified Linear Reservoir model. The parameter C is related to discharge based on Manning’s equation. That relation breathes into an empirical model a dynamic character. A second major contribution is to show that it is possible to simultaneously calculate river stage and aquifer head in the aquifer cell that contains the river. As a result iteration is not necessary to estimate that river cell head as river stage changes, as opposed to what is usually done in most numerical groundwater models. Iteration is still needed for the adjacent cells to the river cell. Because the influence of a change in the adjacent cell head on the river cell head is much delayed and attenuated the iteration is not sensitive to that change. A goal of this document is to show how that method can be used within a simple physically based routing procedure [1] to estimate the river stage that has a definite influence on seepage.
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Abstract Lima, the capital of Peru, and Callao form one of the largest urban centers in South America, with a total population of 10.9 million as of 2017. Three rivers supply water to Lima; however, water for municipal use is mainly taken from the Rimac and Chillon Rivers. Correlating the historic of Rimac flow with the static level of a well in Miraflores, 1 km from Pacific Ocean, was estimated that the residence time, this is the time passing after water infiltrates the ground during a rainfall event until it reaches the Miraflores well, is three years, which agrees with the permeability of the valley, which is in the order of 10-4 ms-1. The average age of water from Lima wells is 6 years, which is consistent with the hypothesis that wells have water from several soil shells. In other hand, the relative abundance of 2H and 18O in wells in the Lima aquifer are in agreement with the hypothesis that the aquifer is recharged with water from rainfall events that occur in the highlands between 3000 and 5000 m above sea level (a.s.l). The contents of 2H,18O, Ca and SO4 of the Graton tunnel sample suggest that it corresponds to water coming from altitudes of 4500 m a.s.l.
Resumen Lima, la capital de Perú, y Callao forman uno de los centros urbanos más grandes de América del Sur, con una población total de 10.9 millones en 2017. Tres ríos abastecen de agua a Lima; sin embargo, el agua para los municipios se toma principalmente de los ríos Rímac y Chillón. Correlacionando el flujo histórico del Rímac con el nivel estático de un pozo en Miraflores, a 1 km del océano Pacífico, se calculó que el tiempo de residencia, esto es el tiempo que transcurre después de que el agua se infiltra en el suelo durante un evento de lluvia, hasta que llega a dicho pozo, es de tres años, lo que está de acuerdo con la permeabilidad del valle, que es del orden de 10-4ms-1. La edad promedio del agua de los pozos de Lima es de 6 años, lo que es consistente con la hipótesis de que los pozos tienen agua de varias capas de suelo. Por otro lado, la abundancia relativa de 2H y 18O en los pozos del acuífero de Lima está de acuerdo con la hipótesis de que el acuífero se recarga con agua de los eventos de lluvia que ocurren en las tierras altas entre 3000 y 5000 m. sobre el nivel del mar (s.n.m). El contenido de 2H, 18O, Ca y SO4 de la muestra del túnel Graton (3100 m.s.n.m.) sugiere que corresponde al agua proveniente de altitudes de 4500 m.s.n.m.
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ABSTRACT Water availability restrictions are already a reality in several countries. This issue is likely to worsen due to climate change, predicted for the upcoming decades. This study aims to estimate the impacts of climate change on groundwater system in the Guarani Aquifer outcrop zone. Global Climate Models (GCM) outputs were used as inputs to a water balance model, which produced recharge estimates for the groundwater model. Recharge was estimated across different land use types considering a control period from 2004 to 2014, and a future period from 2081 to 2099. Major changes in monthly rainfall means are expected to take place in dry seasons. Most of the analysed scenarios predict increase of more than 2 ºC in monthly mean temperatures. Comparing the control and future runs, our results showed a mean recharge change among scenarios that ranged from ~-80 to ~+60%, depending on the land use type. As a result of such decrease in recharge rates, the response given by the groundwater model indicates a lowering of the water table under most scenarios.
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ABSTRACT Transmissivity is an important hydraulic parameter to determine the amount of water passed horizontally across a given saturated thickness of an aquifer. The techniques to quantify this parameter, such as grain size analyses or pumping tests, can have limitations of time/spatial scale, viability, or economically. One technique that can be used, but little adopted, is the capture zone analysis. In this paper, capture zone analytical equations were used to estimate transmissivity values in order to verify the effectiveness of this methodology as alternative in situations where other traditional methods present implementation difficulties. The results were compared with field data estimated by aquifer tests conducted in the same region. A sensitivity analysis was also performed to identify possible discrepancies between the analytical and field data results. The aquifer studied was the Sete Lagoas Karst Aquifer in the urban region of the municipality of Sete Lagoas, Brazil. The method proved to be a viable and economical tool, where the analytical values compared to the aquifer tests showed similarities, being confirmed by a sensitivity analysis. However, a reliable potentiometric surface map, which enables the identification of the parameters for analytical capture zone equations, is needed.
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RESUMO Os metais pesados são contaminantes de grande preocupação ao atingirem os aquíferos, devido à sua toxicidade em determinadas concentrações e a sua difícil remediação. Este estudo visou analisar as concentrações de cobre (Cu), cromo (Cr), ferro (Fe), manganês (Mn) e zinco (Zn) presentes no Sistema Aquífero Bauru (SAB), no Estado de Mato Grosso do Sul, no período de 2009 a 2013. Os teores de Cu, Cr e Zn mantiveram-se dentro dos limites de potabilidade estabelecidos na legislação brasileira, ao contrário do Mn e do Fe. Há, na área de afloramento do Aquífero. Atividades econômicas podem influenciar na qualidade das águas subterrâneas, como, por exemplo, o uso da vinhaça na fertirrigação na cultura de cana-de-açúcar e o curtimento mineral do couro. Este estudo teve o objetivo de reforçar a importância da consolidação de uma rede de monitoramento da qualidade das águas subterrâneas, a fim de estabelecer um zoneamento de vulnerabilidade à poluição por meio de medidas de controle, prevenção e remediação.
ABSTRACT Heavy metals are contaminants of great concern in the aquifers due to their toxicity at certain concentration and difficult remediation. This study aimed to analyze the concentrations of Cu, Cr, Fe, Mn and Zn present in Bauru Aquifer System in Mato Grosso do Sul State, from 2009 to 2013. The content of Cu, Cr and Zn were within the limits of drinking water from Brazilian legislation, unlike Mn and Fe. The use of vinasse in fertigation of sugar cane cultivation and mineral tanning leather can influence the quality of groundwater in the outcropping area of the aquifer. This study reinforces the importance of monitoring groundwater quality in order to establish a zoning of vulnerability to pollution through control measures, prevention and remediation.
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RESUMO No Nordeste do Brasil é bastante comum e variado o uso da coroa-de-frade (Melocactus spp.). Assim, o objetivo deste estudo foi realizar diversas análises em cladódios de coroa-de-frade [Melocactus zehntneri (Britton & Rose) Luetzelburg], para que possamos compreender as razões estes usos. Os cladódios foram coletados na cidade de Campina Grande e levados ao Laboratório de Engenharia de Alimentos da Universidade Federal de Campina Grande, onde foram feitas as seguintes análises: peso, altura, diâmetro, cor, umidade, acidez, pH, ácido ascórbico, carotenoides, flavonoides e compostos fenólicos, tanto na epiderme quanto no parênquima aquífero. Os resultados mostraram que a epiderme tem uma acidez elevada e mais ácido ascórbico, e um pH mais baixo em comparação com o parênquima aquífero. O conteúdo de carotenoides, flavonoides e compostos fenólicos, foram diferentes nas partes estudadas. A epiderme apresentou sempre maiores quantidades de carotenoides, flavonoides e compostos fenólicos em relação ao parênquima aquífero, nas três plantas estudadas, indicando que a maior parte da defesa da planta acontece neste tecido. Mais estudos são necessários com técnicas mais precisas, para identificar os componentes bioativos desta espécie.
ABSTRACT In Northeast Brazil, the use of melon cactus (Melocactus spp.) is quite common and varied. Thus, the present study aimed to perform various analyzes in cladodes of melon cactus [Melocactus zehntneri (Britton & Rose) Luetzelburg], to understand the reasons for the use of this species. The cladodes were collected in the city of Campina Grande and taken to the Food Engineering Laboratory of the Federal University of Campina Grande, where we performed the following analyses: mass, height, diameter, color, moisture, acidity, pH, ascorbic acid, carotenoids, flavonoids and phenolic compounds, both in the epidermis and in the aquifer parenchyma. The results showed that the epidermis has a higher acidity, ascorbic acid content and lower pH compared to the aquifer parenchyma. The contents of carotenoids, flavonoids and phenolic compounds, were different from the both parts analyzed. The epidermis always had greater quantities of carotenoids, flavonoids and phenolic compounds than the aquifer parenchyma for the three plants, showing that most of the plant defense takes place in this tissue. Further studies, with more accurate techniques, are needed to identify the bioactive components of this species.
Asunto(s)
Cactaceae/clasificación , Ácido Ascórbico/análisis , Carotenoides/análisis , Tallos de la Planta/clasificación , Compuestos Fenólicos/análisisRESUMEN
Establecer parámetros edafológicos e hidrogeológicos de la cuenca; y físico-químicos de fertilizantes y plaguicidas, que pudieran servir para el análisis del riesgo de su infiltración. Materiales y métodos: se realizó una investigación exploratoria de campo y gabinete para caracterizar hidrogeológicamente la cuenca. Se analizaron las concentraciones de plaguicidas y nitratos en aguas subterráneas y superficiales. Se consideraron algunas características de vulnerabilidad intrínsecas del acuífero, y otras relacionadas con la retención de contaminantes en suelos. Se determinó el coeficiente de distribución suelo/agua y el factor de retardo para seis sustancias de alto uso y se estimó su riesgo relativo hacia aguas subterráneas. Resultados: Las aguas subterráneas en zonas agrícolas muestran concentraciones de nitrato de dos a tres veces las concentraciones halladas en aguas para consumo humano. Se detectó glifosato en canales de irrigación agrícola. Los parámetros químicos del suelo más fuertemente correlacionados con la concentración de nitratos en aguas subterráneas fueron: a) capacidad de intercambio catiónico, b) relación aluminio: sílice, c) por ciento de retención de nitratos y d) pH del suelo en agua destilada. La concentración de nitratos en aguas subterráneas se relacionó directamente con el porcentaje de materiales finos (por ciento arcillas + por ciento limos) en los suelos. Discusión: Se proponen par metros para la evaluación del riesgo en acuíferos aluviales en la costa Pacífica de Costa Rica donde predomina el uso agrícola. Se considera que la terbutilazina, ametrina, carbendazim, diuron y nitratos representan amenaza importante al acuífero...
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Humanos , Contaminación del Agua/análisis , Contaminación Química del Agua/análisis , Contaminación Ambiental , Contaminación de RíosRESUMEN
Artisanal refining typically involves primitive illegal stills in which crude oil is boiled and the resultant fumes are collected, cooled and condensed in tanks to be used locally for lighting, energy or transport. The distilleries are heated on open fires fed by crude oil that is tipped into pits in the ground. As part of the oil burns away, some seeps into the ground. The waste from the process is stored in open pits thereby increasing the risk of the contamination of the environment and possibly impacting the underground aquifer. It is this concern of crude oil seeping to the groundwater that necessitated the current investigation with the sole objective of assessing the vulnerability of the aquifer to the activities of artisanal refining. Soil, water and crude oil samples from artisanal refining sites were collected according to standard procedures and transferred to the laboratory for analyses to determine their properties. An empirical method was adopted in estimating the permeability. The Kozeny – Carman equation for deriving the coefficient of permeability takes the porosity (η) into account. Using a typical soil porosity η = 0.4, mean particle size = 0.05 and mean viscosity determined from crude samples permeability estimate was calculated to be 3.6 x 10- 8cm/s, infiltration was assessed using a simplified version of Darcy’s law. With a typical superficial soil permeability of 3.6 x 10-8 cm/s, depth of ponding of 0.5m, and a wetting front of 0.4m, an estimated infiltration rate of 1.15 x 10-8cm/s can be expected. Given the infiltration rate and the depth to groundwater (water table is between 3m and 8m), we calculated the time for crude oil contaminant plume to intercept the water table simply reexpressing the equation for velocity as distance/time which results in approximately 4.6 years. The character of the water from the area indicates that groundwater is already being impacted given that artisanal refining has been going on in the area since 2002.
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O presente artigo apresenta estudos para a classificação da vulnerabilidade àcontaminação das águas subterrãneas na região de Campos dos Goytacazes, Rio de Janeiro. O método AVI (Aquifer Vulnerability Index) foi aplicado, utilizando-se o ferramental do Sistema de Informação Geográfica. O método AVI aplica o conceito de resistência hidráulica, dada pela somatória das taxas de espessura da zona não saturada pelas condutividades hidráulicas do meio. Os mapas resultantes mostraram que a região possui sensibilidade àcontaminação das águas subterrâneas, com classificações que variam de "Alta" a "Extremamente alta" (0-10 dias a 10-100 dias, respectivamente). Essa sensibilidade elevada ocorre pela existência de formações de elevada permeabilidade (areias) e níveis de água rasos, típicas ocorrências do delta do rio Paraíba do Sul. O índice vulnerabilidade Alta ocorre: (1) nas margens direita e esquerda do rio Paraíba do Sul, (2) oeste da área (região de confluência do rio Muriaé com o rio Paraíba do Sul), e (3) parte leste da área urbana de Campos dos Goytacazes. Os terrenos com índice de vulnerabilidade Extremamente alta estão localizados: (1) na porção norte (área do Aquífero Barreiras), (2) na área urbana de Campos dos Goytacazes e dos distritos de Saturnino Braga e Mucurepe, (3) porção leste da área, (4) em terreno entre o canal de Cambaíba e o canal de Andreza, e (5) na porção sul da área (Lagoa Feia). Os resultados mostram a caracterização de um importante parãmetro ambiental da região, pretendendo subsidiar políticas públicas para preservação, proteção e uso racional desse importante manancial subterrâneo.
The present paper shows studies aiming groundwater vulnerability evaluation in Campos dos Goytacazes region, Rio de Janeiro, Brazil. The Aquifer Vulnerability Index (AVI) was the vulnerability method applied, using Geographical Information System tools. The AVI Method has adopted the concept of hydraulic resistivity (sum of taxes among unsaturated thickness and hydraulic conductivity). Result maps showed that the region has groundwater vulnerability to contamination from high to extreme levels. The vulnerability varied from "High" to "Extremely high" indexes (from 0-10 days to 10-100 days, respectively). This high vulnerability was attributed to the occurrence of high permeability formations (sands) and shallow water table, typical from the delta of Paraíba do Sul river. High vulnerability index terrains are situated in the following areas: (1) along the right and left banks of Paraíba do Sul river, (2) in the west side of the study area (region of Muriaé and Paraíba do Sul rivers confluence), and (3) in the east side of urban area of Campos dos Goytacazes. The Extremely high index areas are located: (1) in the north portion (Barreiras aquifer), (2) in urban area of Campos dos Goytacazes, besides Saturnino Braga and Mucurepe districts, (3) eastern region of the studied area, (4) in a portion area between Cambaíba and Andreza water drainage channels, and (5) in terrains situated in the south portion of the area (Feia lake). These results showed an important environmental parameter in the river delta region, intending to subsidized public policies to preserve, to protect, and to sustain this important groundwater resource.
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O cultivo da cana-de-açúcar exige a utilização de herbicidas, destacando-se o Diuron e a Hexazinona. Alguns dos poços de abastecimento de Ribeirão Preto (SP) construídos no Aquífero Guarani estão situados em pontos de recarga, e a presença de solo de textura arenosa nessas áreas aumenta a vulnerabilidade da água subterrânea à contaminação por herbicidas. Neste trabalho foram monitorados alguns poços localizados na área de recarga e estudou-se a remoção de Diuron e Hexazinona por meio da adsorção em carvão ativado granular (CAG) e da pré-oxidação com cloro e dióxido de cloro em uma instalação piloto de escoamento contínuo. Verificou-se que o tempo de saturação do CAG no ensaio com a pré-oxidação foi inferior ao obtido no ensaio sem a pré-oxidação com ambos os oxidantes, possivelmente pela formação de subprodutos que competiram com a adsorção dos herbicidas.
The cultivation of sugarcane demands the use of herbicides such as Diuron and Hexazinone. Some supply wells from Ribeirão Preto, SP, Brazil, built in the Guarani Aquifer are located in recharge points, and the presence of sandy Quartzarenic Neosol in these areas increases the vulnerability of the groundwater to contamination from herbicides This paper reports the water quality monitored in some wells located in the recharge area and the removal of Diuron and Hexazinone by means of adsorption in granular activated carbon (GAC), preceded or not by preoxidation with chlorine and chlorine dioxide in a pilot plant. The results indicated that Diuron was more strongly adsorbed than Hexazinone and that the saturation time of the GAC in the test with preoxidation was shorter than in the test without preoxidation, which may have occurred mainly due to the formation of by-products that competed with the adsorption of the herbicides.
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Anomalous concentrations of hexavalent chromium have been detected in ground-water of the Adamantina Aquifer inat least 54 municipalities located in the northwestern region of the State of São Paulo, southeast Brazil, occasionallyexceeding the permitted limit for human consumption (0.05 mg.L-1). An investigation was conducted in the municipality of Urânia, where the highest concentrations of chromium were detected regionally. It was defined that the originof this contamination is natural, since high concentrations of chromium were detected in aquifer sandstones (averageof 221 ppm) and also in pyroxenes (6000 ppm), one of the main heavy minerals found in the sediments. Besides, noother possible diffuse or point sources of contamination were observed in the study area. Stratification of ground-waterquality was observed and the highest concentrations of Cr6+ were detected at the base of the aquifer (0.12 mg.L-1),where ground-water shows elevated values for redox potential (472.5 mV) and pH (8.61). The origin of Cr6+ in water may be associated with the weathering of pyroxene (augite), followed by the oxidation of Cr3+ by manganese oxides. The highest concentrations of Cr6+ are probably related to desorption reactions, due to the anomalous alkaline pHfound in ground-water at the base of the aquifer.
Concentrações anômalas de cromo hexavalente foram detectadas em águas subterrâneas do Aqüífero Adamantina em pelo menos 54 municipalidades localizadas na região noroeste do Estado de São Paulo, sudeste do Brasil, algumas vezes ultrapassando o limite máximo permitido para consumo humano (0,05 mg.L-1). Um estudo foi realizado no município de Urânia, onde as mais elevadas concentrações de cromo da região foram detectadas. A origem da contaminação foi definida como natural, pois foram detectadas concentrações de cromonos arenitos do aqüífero (média 221 ppm) e em piroxênios (6000 ppm), um dos principais minerais pesados encontrados nos sedimentos. Além disso, não foram observadas outras possíveis fontes de contaminação difusas ou pontuais naárea de estudo. Uma estratificação da qualidade da água no aqüífero foi observada e as mais elevadas concentrações de Cr6+ foram detectadas na base do aqüífero (0,12 mg.L-1), onde as águas subterrâneas apresentam valores elevados de potencial redox (Eh = 472,5 mV) e de pH (8,61). A origem do Cr6+ na água deve estar associada com o intemperismo do piroxênio (augita), seguida da oxidação do Cr3+ pelos óxidos de manganês. As maiores concentrações de Cr6+ estão provavelmente ligadas com reações de desorção, devido ao pH anomalamentealcalino da água subterrânea na base do aqüífero.
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Principal component analysis is applied to 309 groundwater chemical data information from wells in the Serra Geral Aquifer System. Correlations among seven hydrochemical parameters are statistically examined. A four-component model is suggested and explains 81 percent of total variance. Component 1 represents calcium-magnesium bicarbonated groundwaters with long time of residence. Component 2 represents sulfated and chlorinated calcium and sodium groundwaters; Component 3 represents sodium bicarbonated groundwaters; and Component 4 is characterized by sodium sulfated with high fluoride facies. The components' spatial distribution shows high fluoride concentration along analyzed tectonic fault system and aligned on northeast direction in other areas, suggesting other hydrogeological fault systems. High fluoride concentration increases according to groundwater pumping depth. The Principal Component Analysis reveals features of the groundwater mixture and individualizes water facies. In this scenery, it can be determined hydrogeological blocks associated with tectonic fault system here introduced.
A Análise de Componentes Principais foi aplicada em 309 dados químicos de águas subterrâneas de poços do Sistema Aqüífero Serra Geral. Correlações entre sete parâmetros hidroquímicos foram examinadas através da estatística. O modelo de quatro componentes foi utilizado por explicar 81 por cento da variância total. A Componente 1 é representada por águas cálcio-magnesianas com longo tempo de residência, a Componente 2 representa águas bicarbonatadas sulfatadas e cloretadas, a Componente 3 representa águas bicarbonatadas sódicas e a Componente 4 é caracterizada por águas de fácies sódica e sulfatada com alto fluoreto. A distribuição espacial das componentes mostra águas com concentrações anômalas ao longo dos sistemas tectônicos de falhas, analisados e alinhados a NE em algumas áreas, sugerindo outros sistemas de falhas hidrogeológicos. As concentrações de fluoreto aumentam de acordo com a profundidade de bombeamento das águas. A Análise de Componentes Principais revelou feições de mistura e individualizou diferentes fácies de águas subterrâneas. Neste cenário, é possível determinar blocos hidrogeológicos associados com os sistemas tectônicos de falhas introduzidos no presente trabalho.