Se realizó un estudio sobre el impacto de los usos actuales en la calidad del agua en la subcuenca del río Jucuapa, Matagalpa, Nicaragua. Se seleccionaron puntos de contaminación en las haciendas cafetaleras, en afluentes de la parte alta de la subcuenca. Se hicieron muestreos mensuales durante los meses de febrero, marzo y abril del 2002, antes y después de la descarga de contaminantes. Se evaluaron variables físico-químicas como temperatura, pH, conductividad eléctrica, sólidos sedimentables, demanda biológica de oxígeno, demanda bioquímica de oxígeno y nitrógeno amoniacal, y bacteriológicas como coliformes fecales en fuentes de abastecimiento de agua potable. Los resultados de los indicadores físico-químicos demuestran una reducción de la calidad del agua en febrero en la Hacienda Los Angeles, lo cual manifiesta la presencia de contaminantes orgánicos (pH 5,41, DBO 84,88 mg/L y DQO 213,82 mg/L). Los otros puntos evaluados no parecen haber sido afectados por contaminantes.También se evaluó la percepción de la población local, instituciones gubernamentales y no gubernamentales sobre la calidad del agua. Si bien los pobladores tienen un conocimiento general sobre el estado actual del río Jucuapa, hay poca conciencia ambiental y poco conocimiento sobre el impacto y consecuencias de las actividades que se realizan en la subcuenca. | A study was carried out to determine the impacts of current uses over water quality in the sub-watershed of Jucuapa River, Matagalpa, Nicaragua. Several pollution sources were located upstream in coffee haciendas with human settlements. A monthly monitoring was undertaken during February, March, and April 2002, before and after the discharge of pollutants. The following physical-chemical variables were measured: Temperature, pH, electric conductivity, sedimentable solids, biological demand of oxygen, biochemical demand of oxygen, and ammoniac nitrogen. In addition, the presence of faecal coliforms on drinkable water sources was determined. In February, the physical-chemical indicators showed a reduction of water quality in Hacienda Los Angeles with a decrease of pH to 5,41, and increases of DBO 84,88 mg/L, and DQO 213,82 mg/L. These results confirm the presence of organic pollution produced by the coffee activities. The other points evaluated did not show water quality decreasing. Perceptions of local population, governmental and non-governmental organizations about water quality were also analyzed. People have a general knowledge about the current situation; however, environmental awareness and knowledge about the impact and consequences of current activities in the sub-watershed are deficient. Slight inter-institutional coordination impedes a correct management of water resources in the zone.

Artigo (especialização) - Universidade Federal de Santa Maria, Centro de Tecnologia, Curso de Especialização para Gestores Regionais de Recursos Hídricos, RS, 2004. | O presente trabalho apresenta uma discussão sobre os critérios das normas brasileiras para o projeto e execução de sistemas de abastecimento de água, e a sua aplicabilidade nos sistemas de abastecimento de pequenas comunidades rurais. Alguns critérios das normas, se aplicados aos sistemas de abastecimento em pequenas comunidades rurais, tornam os mesmos inexeqüíveis, pois o atendimento a estes quesitos normativos encarece de sobremaneira os sistemas. Como a concepção destes sistemas não prevê retorno financeiro com a sua operação, já que o mesmo deve ser gerenciado pela comunidade, torna-se importante minimizar os custos iniciais destes sistemas. Os quesitos normativos que encarecem a execução dos sistemas são tubos e conexões com junta elástica, com diâmetro nominal mínimo de 50 mm e a pressão dinâmica mínima de 100 kPa (10 m.c.a). O trabalho apresenta uma experiência de redução de custos nos projetos de abastecimento d’água para as comunidades rurais do município de Restinga Sêca, RS, obtida com o não atendimento do diâmetro mínimo de 50 mm, utilizando tubulação de PVC com junta soldável e adotando zonas de pressão dinâmica menores do que 10 m.c.a. A execução de sistemas simplificados pode ser, portanto o caminho viável para atender a grande demanda representada pelas pequenas comunidades rurais.

La degradación por fotocatálisis heterogénea del dicloruró de 1,11-dimetil-4,41-bipiridilo (paraquat), herbicida muy usado en nuestro país; usando el reactor fotocatalítico versión solar llamado PHOTO-CREC, diseñado con un sistema de canastas en las cuales está soportado el catalizador dióxido de titanio (TiO2) y dentro de las cuales recircula el agua contaminada. Las concentraciones de contaminante se fueron variando en un rango de concentración de 13.63- 122.71 uM, determinando que el proceso de degradación es más efectivo para bajas concentraciones mientras que a concentraciones altas el porcentaje de degradación decrece, esto es igual para la eficiencia del reactor que es mayor para concentraciones bajas que altas. Dadas las condiciones de operación del equipo se hizo una validación del método mediante un diseño experimental que involucra parámetros estadísticos como: Linealidad, sensibilidad, repetibilidad, límite de detección y cuantificación, precisión y exactitud.

Este trabalho apresenta um panorama das questões legais relacionadas às águas subterrâneas, localizando o recurso hídrico subterrâneo no contexto das Políticas Nacional e Estaduais de Gerenciamento de Recursos Hídricos, entendendo que as águas superficiais e subterrâneas fazem parte de um ciclo que se inter-relaciona em todas as suas fases. Apresenta ainda uma proposta preliminar de incorporação da água subterrânea ao Sistema de Gerenciamento de Recursos Hídricos, de modo que, à medida que se implementem medidas disciplinadoras do uso do recurso hídrico superficial, não aconteça uma “corrida” ao recurso hídrico subsuperficial, perigo iminente caso seu uso não esteja condicionado às normas e que se apliquem as medidas reguladoras praticadas para águas superficiais às águas subterrâneas.

This present study is a resume of hydrogeology study and the abtained results in the building of deep tubular wells built in the area of Caagauzú city where the groundwater Formations Misiones and Independencia occurred. The interpretation of the data allowed stratigraphic regional-local configuration, to know the hydrodynamic’s parameters, geochemistry of the water and, to propose an exploitation criteria which allow the preservation of the groundwater in an over exploitation of the deep-tube well’s battery to cover de demand, to elaborate the adduction project from the location of the deep-tube wells through a meet-box up to the reservoir and the up-tank. At this stage, the project will cover the demand of 37,000 in habitants which means 3,735 connections, for which it necessary to draw out 400 m3/h of groundwater from the Formations Misiones and Independencia subjacent to the region. The factibility studies of the groundwater for the provision potable water for Caaguazú city, covered the stream basin “Toro Blanco”, ”Empalado” and part of the Jhú stream, it was elaborated for Corposana (Essap) with the financial support of Bank Interamerican Development – BID.

Amaranth (Amaranthus hypochondriacus L.), which is considered an alternative source of vegetable protein, is grown particularly under rainfed conditions. Therefore, it is important to look for better management practices that lead to a more efficient use of resources, such as water and essential nutriments, to obtain higher yields. The aim of this work was to determine the influence of nitrogen and plant density on phenology, nitrogen and water use efficiency (WUE), biomass production, and seed yield of amaranth planted on June 11, 1999, with 0, 10, and 20 g m(-2) N and 12.5, 25.0, and 33.3 plants m(-2). With the application of N and with a higher plant density (PD), the efficiency in water use and in N was greater, and in consequence, biomass production and yield increased as well. These increments were higher with higher N level and higher DP. In this way, with 20 g N m(-2) and 33.3 plant m(-2) a biomass production of 2827 g m(-2) and seed yield of 346 g m(-2) were obtained. Phenology was not affected by the treatments. The requirement of sowing heat units to physiological maturity was 1629 UC and 385 mm of water used in evapotranspiration.

The deep-sea phytodetritus at the sediment-water interface was investigated in the continental margin, canyons and interfluves from 260 to 2070 m depth in the northwestern Mediterranean in June 1995. Overlying phytoplankton biomass, hydrodynamics and relationships with meiofauna densities were also evaluated. The phytoplankton biomass was low (< 0.2 µg Chl a l-1), with the lowest standing stocks on the eastern part of the Balearic Basin. Two sedimentary entities were identified: 1) the west coast where pigment concentrations were higher, with an average of 0.38 µg Chl a g-1 dry weight and 4.60 Phaeo a g-1 dw on the first half cm of sediments; and 2) the eastern part of the North Balearic basin where pigment concentrations were significantly lower (0.15 µg Chl a g-1 dw). A north to south gradient was observed, with higher pigment amounts on the Rhodanian slope. Differences were found in the different parts of the studied canyons, with a slight increase in the Axis sites. The vertical pigment repartition was a gradual decrease in the Interfluve sites, whereas concentrations decreased sharply below the first cm in the Axis sites, attesting differences in sedimentation, grazing or bioturbation within the different canyon parts. The north to south gradient in the phytoplankton Chl a/Chl b ratio and sedimented phytodetritus attest geographical differences within phytoplankton assemblages (i.e. diatoms are absent in the south). The epifluorescence tests from the interface revealed the presence of living microphytes at the northern sites, associated with aggregates and faeces. No consistent fluff was evidenced anywhere. The revival tests also agree with a north to south trend. The Meiofaunal density was positively related to the quality of the sedimented layer. A PCA, within the major parameters and factors, illustrates these relationships. All results allow two distinct geographical sectors to be discriminated around the frontal zone: the NW and E sides of the NW Mediterranean Basin, following in particular their contrasted hydrodynamics. The results indicated the relationships within phytoplankton input, underlying phytodetritic layer and meiofauna. They confirm the well-documented statement that demonstrates the deep-sea floor chloropigment concentration to be a good proxy for the overlying primary productivity, but also that some pigment ratios representative of plankton assemblages are preserved on surficial deep sediments, even after sedimentation and grazing. | Se investigó el detrito de agua profunda en la interface sedimento-agua en el margen continental, caniones y interfluves entre 260 y 2070 m de profundidad en el mar Mediterráneo Noroccidental en junio de 1995. La biomasa de fitoplancton flotante, la hidrodinámica, y las relaciones con las densidades de meiofauna fueron también evaluadas. La biomassa de fitotoplancton fue baja (< 0.2 ?g Chl a l-1), con los standing stocks mas bajos en la parte oriental de la cuenca Balear. Dos entidades sedimentarias fueron identificadas: 1) la costa occidental donde las concentraciones de pigmento fueron mas altas: 0.38 ?g Chl a g-1), peso seco (ps) en promedio y 4.60 Phaeo a g-1), ps en el 0,5 cm de sedimento, y 2) la parte oriental de la cuenca Balear Norte donde las concentraciones de pigmentos fueron significativamente mas bajas (0.15 ?g Chl a g-1), ps). Se reconoció un gradiente norte-sur, con valores mas altos de pigmentos en la pendiente Rodaniana. Fueron observadas diferencias en las distintas partes de los cañones estudiados, con un incremente menor en “Eje”. La distribución vertical de pigmentos mostró una disminución gradual en los esta ciones de “Interfluve”, mientras que las concentraciones decrecieron fuertemente debajo del primer centímetro en las posiciones del “Eje”, corroborando diferencias en sedimentación, grazing o bioturbación dentro de las diferentes partes del cañón. El gradiente norte-sur en la relación de Chl a /Chl b de fitoplancton y los fitodetritos sedimentados muestran diferencias geográficas dentro de las asociaciones fitoplanctónicas (i.e. diatomeas están ausentes en el sur). Los tests de epifluorescencia en la interfase revelaron la presencia de microfitas vivientes en los estaciones del norte, asociados con agregados y faeces. Evidencia de un “fluff” consistente no fue encontrada. Los tests de “revival” también coinciden con una tendencia norte-sud. La densidad de meiofauna se relaciona positivamente con la cualidad de la capa sedimentada. Un análisis de componentes principales, con los mayores parámetros y factores, ilustra estas relaciones. Todos los resultados permiten discriminar dos sectores geográficos bien distintos cerca de la zona frontal: los lados NW y E de la cuenca Mediterránea NW siguiendo, en particular, sus contrastantes hidrodinámicas. Los resultados muestran las relaciones dentro del input de fitoplancton, yaciendo debajo de la capa fitodetrítica y la meiofauna. Esto confirma la afirmación que la concentración de cloropigmentos en el fondo del océano profundo es un buen indicador de la productividad primaria en aguas superiores, y también que algunos ratios de pigmentos, representativos de asociaciones planctónicas, son preservados en sedimentos superficiales profundos, aun después de la sedimentación