15 páginas, 5 tablas, 7 figuras | [EN] A method for the determination of organic carbon in seawater is described; the organic matter is oxidised to CO2 with peroxidisulphate under UV ligth, and is detected by a colorimetric method where the CO2, after dialysis through a silicon membrane, produces a decrease in the colour of an alkaline phenolphthalein solution proportional to the CO2 concentration. A theoretical study is carried out of the carbonic and indicator system to fix the optimum concentration of carbonate-bicarbonate buffer and phenolphthalein in accordance with the dialysis yield of the CO2 and the concentration of total organic carbon (TOC). For seawater it is advisable to prepare the colour reagent with a concentration of 500 μmol dm-3 in sodium ion and of 30 μmol dm-3 in phenolphthalein, with an adjustment of the pH to 9.60. | [ES] Se describe un método para la determinación de carbono orgánico en agua de mar mediante la oxidación de la materia orgánica a CO2 con peroxidisulfato bajo luz UV. La detección es por un método colorimétrico, donde el CO2, después de dializar a través de una membrana de silicona, produce un descenso en el color de una disolución alcalina de fenolftaleina que es proporcional a la concentración de CO2. Se hace un estudio teórico del sistema carbónico e indicador para fijar las concentraciones óptimas de tampón carbonato-bicarbonato y fenolftaleina de acuerdo con el rendimiento de la diálisis de CO2 y la concentración de carbono orgánico total (TOC). Para el agua de mar se aconseja preparar el reactivo de color con una concentración en ion sodio de 500 μmol dm-3 y en fenolftaleina de 30 μmol dm-3 con un ajuste de pH a 9,60 | Peer reviewed

Two experiments were carried out under greenhouse conditions with two different beans (Phaseolus vulgaris L.) named INIA and CP. In the first experiment the transpiration pattern was studied in both bean material grown under well irrigated or water stress conditions. In both water regimes the bottom leaves transpired less than the top ones, although the transpiration ratio in the water stress treatment decreased drastically, as expected. The top exposed leaf was the last to reduce its rate of transpiration. There was no difference in the transpiring pattern in both materials. In the second experiment, water relation parameters were studied for both beans materials in five water regimes treatments. The parameters were relative water content; total water potential; solute potential and turgor potential. The water regimes applied were well irrigated control and four different water stress treatments. These last treatment were applied following the suggestions of Larque-Saavedra et al (1984) for the initiation of drought. There were differences in the relative water content of both bean materials. The CP material had greater relative water content. However, these values were not significantly different.

Tesis (M. Sc) -- CATIE, Turrialba (Costa Rica), 1988 | Este estudio se realizó en la cuenca del Río Barranca, de la vertiente del Pacífico de Costa Rica, la cual tiene una superficie de 478,88 km{ostrok}. Su principal objetivo consistió en determinar la relación entre las disponibilidades y las demandas de agua de tipo consuntivo que se presentaran en la cuenca dentro de un horizonte de planificación propuesto de 20 años (1988-2008). Una de las principales conclusiones del estudio es que es necesario analizar los proyectos hidroeléctricos identificados considerando los usos múltiples de los embalses a fin de incluir en los análisis económico y financiero los beneficios adicionales que se obtendrían de éstos y no solamente los beneficios del sector energía. Por otra parte, se detectó un problema típico de falta de políticas nacionales de planificación de recursos hídricos, en donde las instituciones nacionales han identificado proyectos para el aprovechamiento de este recurso sin considerar las inter-relaciones de sus proyectos con los de las otras instituciones, ni la inter-relación del recurso agua con los demás recursos naturales de la cuenca.

The negative water balance in the Canary Islands makes it nessesary to recycle for agriculturalñ treated wastewater. This paper studies the absorption by the plant of the N content of the treated wastewater and the effect on yiels in comparison with mineral fertilizers dissolved in distilled water in a quantity equivalent to the content of the water under study. In the conditions of our assay and taking into account greater irrigation dose, the yield results as dry matter weight and $ N absorbed by the plants, never were significatively lower than those obtained with equivalent dose of mineral fertilizers though the N concentration in the treated wastewater were not sufficient to provide enough N to the culture. | Peer reviewed