RESUMEN. El objetivo del presente estudio fue analizar los niveles de plomo (Pb), cadmio (Cd), aluminio (Al), zinc (Zn), cobre (Cu) y cromo (Cr) en agua de bebederos de presión distribuidos en el Campus de la Universidad de San Paulo, Ribeirão Preto, Brasil. Fueron colectadas 30 muestras aleatoriamente obtenidas en diferentes instancias del Campus y analizadas por Espectrofotometría de Absorción Atómica. De acuerdo con la Guía de Valores Máximos Recomendados de la Organización Mundial de la Salud (OMS), plomo, cadmio y zinc se detectaron en concentraciones superiores a las recomendadas en 40%, 20% y 13% de las muestras, respectivamente. Los resultados son analizados considerando aspectos nutricionales y toxicológicos, referente a la presencia de metales esenciales y tóxicos para el hombre. Comparando los límites reglamentados en diez países de América, se pone de manifiesto la necesidad de un consenso en el establecimiento de las concentraciones máximas de metales en agua potable. La Ingesta Diaria Tolerable, debe ser la base para el establecimiento del nivel máximo de metales en agua, con la finalidad de prevenir la aparición de enfermedades asociadas a largo plazo.<br>SUMMARY. The purpose of this study was to analyze the levels of lead (Pb), cadmium (Cd), aluminum (Al), zinc (Zn), cooper (Cu) and chromium (Cr) in the water of drinking fountains distributed in the Campus of the University of São Paulo, Ribeirão Preto, Brazil. Thirty random samples were collected in different parts of the Campus that were analyzed by Atomic Absorption Spectrophotometry. According to WHO’s Drinking Water Guidelines; lead, cadmium and zinc were found in concentrations higher than those recommended in 40%, 20% and 13% of the samples, respectively. The results were analyzed considering nutritional and toxicological aspects related to the presence of essential and toxic elements for the human being. Reviewing the regulatory limits established in ten countries of America, authors focus in the necessity to find a consensus in the establishment of the higher levels of heavy metals in potable water. The tolerable daily intake, have to be the basis to assure the prevention of diseases associated with a long-term ingestion of these elements through foods.

This publication provides guidance to water-sector decision makers and planners on how to deal with the quality dimension of groundwater resources management in the World Bank's client countries. There is growing evidence of increasing pollution threats to groundwater and some well-documented cases of irreversible damage to important aquifers. This guide has been produced in the belief that groundwater pollution hazard assessment must become an essential part of environmental best practice for water supply utilities. The guide is particularly relevant for the World Bank's Latin American and Caribbean Region, where many countries have initiated major changes to modernize their institutional and legal framework for water resources management, but may not yet have considered groundwater at the same level as surface water, because of lack of awareness and knowledge of groundwater issues and policy options.

he objective was to characterize the water quality in a section of the Grijalva River and in some of its tributaries on the border between the States of Chiapas and Tabasco, in the rainy and dry seasons. Twenty-three physical, chemical and microbiological parameters as well as contaminants were determined. The values obtained were compared with the maximum permissible limits (MPLs) for water use and human consumption set out in O cial Mexican standard NOM-127-SSA1-1994, and with the water quality classi cation scale of the Comisión Nacional del Agua (CONAGUA). The water quality in the studied section of the Grijalva River decreases as it descends to more populated areas of the State of Tabasco. Water turbidity and E. coli coliform levels increase, both in the river channels and in sources destined for human consumption. For the other variables evaluated, there are acceptable water quality characteristics, mainly in the dry season, except for mercury, which occurs at levels higher than those recommended. Further studies on the presence of mercury in the Grijalva River basin are recommended.

he objective was to characterize the water quality in a section of the Grijalva River and in some of its tributaries on the border between the States of Chiapas and Tabasco, in the rainy and dry seasons. Twenty-three physical, chemical and microbiological parameters as well as contaminants were determined. The values obtained were compared with the maximum permissible limits (MPLs) for water use and human consumption set out in O cial Mexican standard NOM-127-SSA1-1994, and with the water quality classi cation scale of the Comisión Nacional del Agua (CONAGUA). The water quality in the studied section of the Grijalva River decreases as it descends to more populated areas of the State of Tabasco. Water turbidity and E. coli coliform levels increase, both in the river channels and in sources destined for human consumption. For the other variables evaluated, there are acceptable water quality characteristics, mainly in the dry season, except for mercury, which occurs at levels higher than those recommended. Further studies on the presence of mercury in the Grijalva River basin are recommended.

RESUMEN. El objetivo del presente estudio fue analizar los niveles de plomo (Pb), cadmio (Cd), aluminio (Al), zinc (Zn), cobre (Cu) y cromo (Cr) en agua de bebederos de presión distribuidos en el Campus de la Universidad de San Paulo, Ribeirão Preto, Brasil. Fueron colectadas 30 muestras aleatoriamente obtenidas en diferentes instancias del Campus y analizadas por Espectrofotometría de Absorción Atómica. De acuerdo con la Guía de Valores Máximos Recomendados de la Organización Mundial de la Salud (OMS), plomo, cadmio y zinc se detectaron en concentraciones superiores a las recomendadas en 40%, 20% y 13% de las muestras, respectivamente. Los resultados son analizados considerando aspectos nutricionales y toxicológicos, referente a la presencia de metales esenciales y tóxicos para el hombre. Comparando los límites reglamentados en diez países de América, se pone de manifiesto la necesidad de un consenso en el establecimiento de las concentraciones máximas de metales en agua potable. La Ingesta Diaria Tolerable, debe ser la base para el establecimiento del nivel máximo de metales en agua, con la finalidad de prevenir la aparición de enfermedades asociadas a largo plazo. | SUMMARY. The purpose of this study was to analyze the levels of lead (Pb), cadmium (Cd), aluminum (Al), zinc (Zn), cooper (Cu) and chromium (Cr) in the water of drinking fountains distributed in the Campus of the University of São Paulo, Ribeirão Preto, Brazil. Thirty random samples were collected in different parts of the Campus that were analyzed by Atomic Absorption Spectrophotometry. According to WHO’s Drinking Water Guidelines; lead, cadmium and zinc were found in concentrations higher than those recommended in 40%, 20% and 13% of the samples, respectively. The results were analyzed considering nutritional and toxicological aspects related to the presence of essential and toxic elements for the human being. Reviewing the regulatory limits established in ten countries of America, authors focus in the necessity to find a consensus in the establishment of the higher levels of heavy metals in potable water. The tolerable daily intake, have to be the basis to assure the prevention of diseases associated with a long-term ingestion of these elements through foods.

Se estudian suelos, sedimentos y aguas de tres lagunas situadas en Cantalejo (Segovia), se determinan los contenidos en Zn, Cd, Pb y Cu en los tres medios y se relacionan las concentraciones en suelos con las fracciones granulometricas, materia organica y pH.

El presente trabajo se centra en una investigación enfocada en la calidad del recurso hídrico, aportando información para la implementación de una metodología aplicable para la validación de los datos de la Red de Isotopía; en cuanto a la Red de Calidad de Agua se realizó una investigación relacionada con los parámetros de calidad de metales pesados en sedimentos, tomando como referencia las concentraciones limite en la normativa canadiense, identificando las estaciones más contaminadas en materia de metales pesados, sus posibles causas y consecuencias. | The present is focused on a research about of the quality of the water resource, providing information for the implementation of an applicable methodology for the validation of the data of the Isotope Network; Regarding the Water Quality Network, an investigation was carried out related to the quality parameters of heavy metals in sediments, taking as a reference the limit concentrations in Canadian regulations, identifying the most polluted stations in terms of heavy metals, their possible causes and consequences. | Instituto de Hidrología, Meteorología y Estudios Ambientales

Los metales pesados (MP) pueden afectar las relaciones hídricas de la planta de muchas formas. El Hg inhibe la actividad de las acuaporinas, proteínas que forman los canales transportadores de agua, y de esta manera afecta la conductividad a nivel celular y de tejidos en zonas específicas de la raíz, así como el volumen de las células guarda modificando los movimientos estomáticos. Además, junto con otros metales pesados, el Hg produce cambios morfológicos como el acortamiento o modificación en la elasticidad de las raíces, disminuyendo el área efectiva para la toma de agua. En hojas, el cambio en el número de estomas y de tricomas causado por el Hg, altera la tasa de transpiración. En este artículo se revisa el efecto del Hg sobre el transporte de agua en la planta a nivel celular y su relación con el estatus hídrico de ésta. Además, se presentan avances recientes en el conocimiento de las acuaporinas basados en la utilización del Hg como inhibidor de su actividad.Palabras clave adicionales: acuaporinas, conductividad hidráulica, raíces, estomas. | Heavy metals could affect hydric relationships in plants in many ways. Mercury inhibits activity of aquaporins, the proteins that form the chanels-transporters of water and, thus, affects water conductivity of cells and tissues of special root zones as well as volume of guard cells modifying stomatal movements. Mercury produces morphological changes in plants, the effects typical for other heavy metals, such as shortening of root or decrease in root elasticity, thus reducing effective area for water absorption. In leaves, the changes in number of stomata and trichomes caused by the effects of Hg alter the transpiration rates. In the present article, the effects of Hg over the water transport in plants at cellular level and whole hydric status of plants are revised. Additionally, the recent studies on aquaporin functioning are discussed, with Hg used as an agent to inhibit aquaporin activity.

The Cataniapo River basin--which is the only source of water for the town of Puerto Ayacucho, in the Venezuelan Amazon--is being subjected to intense environmental pressure by unplanned agricultural and urban local development. In order to describe the spatial-temporal variation in water quality, water and sediment samples were collected quarterly from the upper, middle and lower sections of the Cataniapo River between 2000 and 2003. The following parameters and compounds were determined: suspended solids, alkalinity, pH, conductivity, dissolved oxygen, total and fecal coliforms, hydrocarbons, heavy metals (Pb, Hg, Ni, Zn, Cu and Cr) and organochlorine insecticides. Analyses were performed using atomic absorption spectrophotometry and field sensors. Values for pH oscillated around 5 units in the three sections of the river, which is considered normal for this type of clear water according to existing historical records. Nevertheless, temporary acidification was observed during the period of low waters, or the dry season, when pH values decreased to roughly 4. Continuous and elevated concentrations of total and fecal coliforms of up to 14 000 and 2 800 organisms per 100 ml-1, respectively, were detected. The highest concentrations of heavy metals found in the water were Cu 0.09; Cr 0.05; Pb 0.24; Zn 0.33; Ni 1.32; Hg 0.02 mg l-1); with Pb, Ni and Hg being higher than the international norms recommended for the normal development of aquatic life, in general, and for human consumption, in particular. The presence of two organochlorinated insecticides were found Aldrin (0.072 μg l-1) and β-BHC (0.126 μg l-1) which are banned from the basins due to their "protected area status." The results obtained by this investigation revealed a deterioration in the quality of the water in the lower Cataniapo River. Although this is localized and moderate, it needs to be addressed by implementing alternative ecological management strategies that include the careful use of available aquatic resources. | La cuenca del río Cataniapo, única fuente de agua para la ciudad de Puerto Ayacucho en la amazonía venezolana, está siendo sometida a una intensa presión ambiental por la anárquica expansión agrícola y urbanística local. Con la finalidad de caracterizar la alteración espacio-temporal en su calidad de agua fueron colectadas trimestralmente muestras de agua y sedimento en las secciones alta, media y baja del río Cataniapo entre los años 2000 y 2003. Fueron determinados los siguientes parámetros y compuestos: sólidos suspendidos, alcalinidad, pH, conductividad, oxígeno disuelto, coliformes totales y fecales, hidrocarburos totales, metales pesados (Pb, Hg, Ni, Zn, Cu y Cr) e insecticidas organoclorados. Las técnicas analíticas empleadas para los distintos análisis fueron la espectrofotometría de absorción atómica y el uso de sensores de campo. Los valores de pH oscilaron alrededor de las cinco unidades en las tres secciones del río, valor considerado normal para este tipo de aguas claras, según los registros históricos existentes; sin embargo, fue observada una acidificación temporal en la hidrofase de aguas bajas o época seca cuando el pH disminuyó hasta valores cercanos a cuatro. Fueron detectadas continuas y elevadas concentraciones de coliformes totales y fecales, alcanzando máximas de 14 000 y 2 800 organismos 100 ml-1, respectivamente. Las concentraciones más altas encontradas para los metales pesados en el compartimiento agua fueron: Cu, 0.09; Cr, 0.05; Pb, 0.24; Zn, 0.33; Ni, 1.32; Hg, 0.02 mg l-1, encontrándose el contenido de Pb, Ni y Hg por encima de las normativas internacionales para el normal desarrollo de la vida acuática en general y para el consumo humano en particular. Fueron registrados dos insecticidas organoclorados prohibidos en la cuenca debido a su figura administrativa de área protegida: Aldrín (0.072 μg l-1) y β-BHC (0.126 μg l-1). Los resultados obtenidos en esta investigación revelaron un deterioro de la calidad de agua de la sección baja del río Cataniapo, que aunque es muy localizado y moderado, es necesario remediar implementando alternativas de gestión ecológica, que incorporen el principio de precaución en el aprovechamiento de sus recursos acuáticos.