El objetivo del trabajo fue evaluar el efecto de períodos cortos de suplementación energética pre faena sobre parámetros productivos, calidad de la canal y de la carne de 40 vacas de invernada Hereford adultas, con un peso vivo promedio de 458.3 ± 43.6 Kg. Las mismas fueron manejadas sobre campo natural y estratificadas por peso y estado corporal, asignándolas al azar a dos tratamientos, T1: Testigos no suplementadas y T2: suplementadas con concentrado (40 por ciento de maíz y un 60 por ciento de cebada), a razón de 1 por ciento depeso vivo. Se realizó un acostumbramiento gradual durante 10 días, seguido de un período de evaluación de 20 días. La faena se llevó a cabo en el frigorífico Casa Blanca S.A. (Paysandú) mediante el proceso tradicional, luego de terminado el período de suplementación a fecha fija. Los animales fueron trasladados bajo las mismas condiciones (en el mismo embarque y con el mismo tiempo de espera previo a la faena); se realizó el seguimiento de la carcasa dentro de la playa de faena a través de etiquetas y se determino el peso vivo y peso dela canal.

Apesar do conhecimento existente sobre a erosão das terras cultivadas, há situações de uso e manejo do solo que necessitam de estudos mais aprimorados. Apoiado nisso, realizou-se esta pesquisa com o objetivo de avaliar a erosão hídrica pluvial do solo na cultura do milho (Zea mays L.), implantada em área de campo nativo, nos métodos de preparo escarificação e semeadura direta e nos tipos de adubação mineral (fertilizante contendo N e P) e orgânica (cama seca de aviário). O estudo foi desenvolvido a campo, na EEA/UFRGS, em Eldorado do Sul (RS), no verão de 2006/2007, aplicando-se chuva simulada sobre um Argissolo Vermelho distrófico típico com textura francoarenosa na camada superficial e declividade média de 0,13 m m-1. Foram realizados dois testes de erosão na pesquisa, cada um deles na intensidade constante de chuva de 64 mm h-1 e com duração de 1,5 h, usando-se o aparelho simulador de chuva de braços rotativos. O primeiro teste foi realizado logo após a implantação dos tratamentos, na semeadura do milho, e o segundo 75 dias mais tarde, no florescimento da cultura. Avaliaram-se atributos de solo e planta nas parcelas experimentais e de erosão hídrica no escoamento superficial. Observou-se que o crescimento da cultura e as perdas pela erosão foram influenciados pelos tratamentos estudados. O milho cresceu melhor na escarificação, independentemente da adubação. A perda de solo ocorreu somente na escarificação e no primeiro teste de erosão, em quantidade muito pequena, independentemente da adubação. A perda de água, de matéria orgânica e de nutrientes ocorreu em todos os tratamentos e testes de erosão, em quantidades variadas, na maior parte das vezes tendo sido maiores na semeadura direta, independentemente da adubação e do teste de erosão, e muito maiores no primeiro teste, em qualquer um dos tratamentos. O pH da enxurrada variou pouco e não mostrou tendência entre os tratamentos e testes de erosão, enquanto a condutividade elétrica e as concentrações médias de matéria orgânica e de nutrientes variaram amplamente e mostraram tendências claras. Este último aspecto repetiu com as quantidades totais acumuladas de matéria orgânica e nutrientes perdidas pela erosão. As maiores quantidades totais acumuladas de nutrientes perdidas pela erosão foram observadas para o K tanto na adubação mineral quanto na adubação orgânica, para o P na adubação mineral e para o N tanto na adubação mineral quanto na adubação orgânica, nesta ordem de valores decrescentes e todos na semeadura direta. Quantidades totais acumuladas de nutrientes perdidas pela erosão menores do que as recém-mencionadas, porém ainda expressivas, foram observadas para o K praticamente no restante dos tratamentos e para o N na escarificação com adubação orgânica. | Despite the available knowledge on erosion of cultivated lands, there are situations of soil use and management that need more detailed studies. Based on that, this research work was accomplished with the objective of evaluating soil erosion by rainfall from an area of native pasture cropped with corn (Zea mays L.), under reduced-tillage and no-tillage, and mineral (chemical fertilizer containing N and P) and organic (poultry litter) fertilization. The study was developed in the field, at the Agriculture Experimental Station of the Federal University of Rio Grande do Sul (EEA/UFRGS), RS, Brazil, in the summer of 2006/2007, by applying simulated rainfall on an Ultisol having sandy loam texture in the surface layer and 0.13 m m-1 average slope steepness. Two erosion tests in the research, were performed, each one of them at the constant 64.0 mm h-1 rainfall intensity and for 1.5 h duration, by using the rotating boom rainfall simulator. The first test was performed soon after treatments establishment, at corn seeding, and the second one 75 days later, at corn tasseling. Soil and plant attributes were evaluated in the experimental plots and those of water erosion in the surface runoff. It was observed that the crop growth and the erosion losses were influenced by the studied treatments. Corn grew better in reduced-tillage, regardless of fertilization type. Soil loss occurred only in reduced-tillage and in the first erosion test, in very small amount, regardless of the fertilization type. Water, organic matter, and nutrients losses occurred in all treatments and erosion tests, in variable amounts, generally being higher in no-tillage and in the first erosion test. The pH of the runoff varied little and no trends in treatments and erosion tests were observed, whereas electric conductivity and mean concentrations of organic matter and nutrients varied widely and clear trends could be observed. This latter aspect repeated with the accumulated total amounts of organic matter and nutrients lost by erosion. The highest accumulated total amounts of nutrients lost by erosion were observed for K in both organic and mineral fertilization, for P in mineral fertilization, and for N in both organic and mineral fertilization, in this decreasing order of values and all under no-tillage. Accumulated total amounts of nutrients lost by erosion lower than the ones just mentioned, but still significant, were observed for K in practically all other treatments and for N under reduced-tillage with organic fertilization.

This work proposes a methodology for sugarcane expansion monitoring and its possible impacts in the regional hydric dynamic through the real evapotranspiration estimation (ET) based on Terra/Modis satellite data. The methodological approach is based on a systematic and automatic land use mapping that uses a sequence of temporal profiles Vegetation Index (NDVI) built with Modis data JONATHAN (2005). Previous Studies (MEIRELLES et al, 2006 JONATHAN et al 2008); as well as some preliminaries results developed on the scope of this work, shown the applicability of the proposed method as a tool for regional monitoring land use dynamic and its impacts. The real evapotranspiration is calculated through SEBAL algorithm (Surface Energy Balance for Land) developed by BASTIAANSSEN (1995) for energy balance estimation. The study area is the southern portion of Goias state in Brazil, where the sugar cane expansion has being increasing drastically in the last decades. O objetivo deste trabalho é apresentar uma combinação de procedimentos metodológicos, relacionados à distinção da cultura da cana-de-açúcar por meio do aperfeiçoamento de uma metodologia de classificação automática do uso do solo, desenvolvida por JONATHAN (2005, (a) e (b)), e da utilização do Modelo SEBAL para a estimativa da ET real, ambos a partir de dados do sensor MODIS/Aqua.

El rol del Gobierno de El Salvador en la aplicabilidad de los compromisos internacionales adquiridos en materia de recursos hídricos para una gestión sustentable del agua-- Participación de las organizaciones ecológicas y no gubernamentales a través de proyectos y programas orientados a la gestión sustentable del agua-- Gestión sustentable del agua como parte fundamental para el logro de los objetivos de desarrollo del milenio.

El Corregimiento de Tribunas Córcega cuenta con una riqueza hídrica invaluable, sin embargo la inadecuada gestión ambiental que existe en el Corregimiento pone en peligro la calidad y continuidad del agua presente en las quebradas y ríos que lo atraviesan, y las cuales se consideran fuentes alternas de abastecimiento para la ciudad de Pereira. Entre las fuentes hídricas más importantes del Corregimiento se encuentran: Los ríos Barbas, Consota, quebrada Cestillal, Oso, Condina, Tinajas, Peñitas, Bizcochuelo, Viboral, La Mesa, San José y Balsora. La Empresa de Servicios Públicos de Tribunas Córcega ¿ ESPTRI, es la entidad encargada de prestar el servicio de acueducto, de aseo y de alcantarillado a la mayor parte de la población del Corregimiento. Esta empresa se ha convertido en un eje articulador de los procesos que se desarrollan en la comunidad puesto que sus instalaciones se convierten en espacios de discusión de temas de diversa índole por parte de las instituciones públicas, la comunidad e incluso la academia. El siguiente trabajo contiene un estudio de riesgo de la calidad del agua para consumo humano realizado en la ESPTRI con base en la ¿Guía Técnica de Soporte para Identificar, Reducir y Formular Planes de Contingencia por Riesgos sobre la Calidad del Agua para Consumo Humano¿, desarrollada por elMinisterio de la Protección Social y el Ministerio de Ambiente, Vivienda y Desarrollo Territorial en el año 2008 y la cual se enmarca en el decreto 1575 de 2007. Además incorpora una serie de estrategias diseñadas con el fin de orientar los procesos de Gestión Ambiental del Recurso Hídrico ¿ GARH en el Corregimiento de Tribunas Córcega y la Empresa de Servicios Públicos de Tribunas Córcega ¿ ESPTRI. El trabajo se divide en cuatro capítulos: 1. Acerca del Proyecto; 2. Estudio de Riesgo; 3. Estrategias de Gestión Ambiental de Recurso Hídrico y 4. Resultados, Conclusiones y Recomendaciones. Las estrategias propuestas en el presente estudio.

Como propuesta para la evaluación de algunos de los impactos atribuibles a la implementación de la política ambiental que establece los programas para el uso eficiente y ahorro de agua, se planteó la construcción de un modelo de simulación a partir de la utilización del enfoque metodológico de dinámica de sistemas Parael desarrollo de esta evaluación se reunió información necesaria para la caracterización del sistema que involucra esta eficiencia y ahorro, tomando como punto de partida lo establecido en la Ley 373 de 1997 y sus decretosreglamentarios. Este marco normativo define en este aspecto el accionar de las empresas prestadoras del servicio de agua potable y saneamiento básico en Colombia, y brinda las herramientas necesarias para la formulación de los programas de uso eficiente y ahorro de agua desde los cuales se materializan los propósitos de la política ambiental. Por otra parte, fueron tomados en cuenta elementos teórico conceptuales que definen los diferentes enfoques de gestión desde los cuales se aborda la problemática a nivel mundial. Los datos que nutren el modelo utilizado en la evaluación de impacto, provienen de la información registrada en la ciudad de Pereira, y caracterizan el comportamiento de la oferta y demanda deagua en el área urbana de este municipio. Esta información, así como las estrategias planteadas en el programa para uso eficiente y ahorro del agua implementado por la Empresa de Acueducto y Alcantarillado de la Ciudad de Pereira S.A. E.S.P. durante el quinquenio 2003- 2007. | As a suggestion to evaluate some of the attributable impacts to the environment policy implementation that establishes the programs for water saving and efficient usage, the construction of a simulating model from the utilization of a methodological dynamic systems focus was proposed. For the evaluation development, all the necessary information was put together for the characterization of the system that involves this efficiency and saving, starting from what is established in law 373/1997 and its statutory decree. This regulatory framework defines the work of drinking water and basic sanitation service providers in Colombia and offers the necessary tools for the formulation of efficient usage and water saving programs from which the environmental policy´s intentions materialize. On the other hand, conceptual and theoretical elements which define the different management focus from which the worldwide problematic level is approached were taken into consideration. The data that feeds the model used in the impact assessment comes from the information registered in the city of Pereira, depicting water supply and demand behavior in the urban area of this county. This information as well as the proposed strategies for water saving and efficient usage program implemented by the Empresa de Acueducto y Alcantarillado de la Ciudad de Pereira S.A E.S.P during the years 2003 thru 2007, brought up some of the impacts generated by the implementation of the environmental policy on the water resources and the consumption pattern behavior in the city of Pereira. The impact assessment from the dynamic systems allowed the establishment of alternative, strategies and important parameters to accomplish the set objectives in the environmental policy as well as the efficiency evaluation of some of the criteria established in it.

A instabilidade volumétrica de solos devido à mudança no teor de água é complexa e influenciada por vários fatores, entre os quais se incluem o tipo de solo, condicionantes climáticos e estados de tensão. Os Vertissolos estão entre os solos que experimentam mudança de volume, sendo uma de suas principais características morfológicas os slickensides, resultantes da sua capacidade de se contrair e fissurar com o ressecamento e se expandir com o umedecimento. Os solos que variam de volume, quando inundados por água, demandam cuidado extra, independentemente do uso que se quer dar a eles: agropecuário, para obra de engenharia ou ambos. O objetivo deste trabalho foi avaliar, por meio de ensaios edométricos simples e duplos com diferentes valores de umidade inicial e tensões externas aplicadas, a variação do volume e da tensão de expansão do solo, devido à mudança do teor de água, em um Vertissolo coletado no município de Petrolândia-PE. A tensão de expansão foi avaliada por seis métodos distintos. Os resultados mostram que a expansão, contração ou colapso do solo dependem do teor de umidade inicial e da tensão externa aplicada. A tensão de expansão é influenciada pelo caminho de tensão aplicado. As variações de volume, com o tempo, devido ao processo de mudança de umidade do solo, podem ser de expansão, expansão e colapso e só de colapso ou contração. Conclui-se que a variação de volume, devido à variação do teor de água, está associada à condição inicial em que se encontra o solo e àquela a que será submetido.<br>The volumetric instability of soils due to changes in the water content is complex and is influenced by several factors, such as soil type, climate conditions and tension state. Vertissols are soils that undergo variations in volume. One of their most important morphological features are slickensides that reflect contraction and fissuring during the drying process, and swelling during wetting. Soils that vary in volume when flooded require special care regardless of their use for agriculture, construction or both. The objective of this study was to evaluate, through both conventional edometric tests and suction-controlled tests, with different initial moisture and externally applied tension, the changes in volume and expansion tension of the soil, due to variations in the water content of a Vertisol from Petrolândia-PE. The expansion tension was measured by six methods. Results showed that soil expansion, contraction or collapse depend on the initial moisture and external tension. The expansion tension is influenced by the tension path. The volume variations with time when the soil is drying could be due to expansion, expansion and collapse and only collapse or contraction. It was concluded that the volume changes due to the water content variation are associated to the soil initial conditions and those that the soil is expected to undergo in the future.

Hydrologic conceptual models of groundwater/surface-water interaction in a saprolite-fractured bedrock geological setting often assume that the saprolite zone is hydraulically more active than the deeper bedrock system and ignore the contribution of deeper groundwater from the fractured bedrock aquifer. A hydraulic, hydrochemical, and tracer-based study was conducted at Scott Creek, Mount Lofty Ranges, South Australia, to explore the importance of both the deeper fractured bedrock aquifer system and the shallow saprolite layer on groundwater/surface-water interaction. The results of this study suggest that groundwater flow in the deeper fractured bedrock zone is highly dynamic and is an important groundwater flow pathway along the hillslope. Deep groundwater is therefore a contributing component in streamflow generation at Scott Creek. The findings of this study suggest that hydrologic conceptual models, which treat the saprolite-fractured bedrock interface as a no-flow boundary and do not consider the deeper fractured bedrock in hydrologic analyses, may be overly simplistic and inherently misleading in some groundwater/surface-water interaction analyses. The results emphasise the need to understand the relative importance of subsurface flow activity in both of these shallow saprolite and deeper bedrock compartments as a basis for developing reliable conceptual hydrologic models of these systems.

Meat samples of loin pork and breast broiler were examined in two commercial plants to determine the incidence of drip loss and its relationship with muscle pH and colour. The drip loss was high in pork and its correlation with the pH, measured before the first 30 minutes after slaughter, was very low (-0.20). There was a higher correlation between drip loss and L* value (0.56). In broiler, a higher correlation between drip loss and pH was found (-0.57). However, there was a nonsignificant correlation between drip loss and pH in contrast with other studies where L* value seemed to be of more predictive value than pH. These results indicate that pH and colour, measured commercially, could be insufficient to discriminate the meat with superior quality.

Las aves marinas enfrentan compromisos únicos con relación a la cantidad de agua absorbida por el plumaje y las habilidades tanto de vuelo como de buceo debido a las restricciones impuestas por el hábitat marino y sus historias de vida. En el presente estudio se analizan las propiedades estructurales de las plumas y los efectos mecánicos de despegue y buceo asociados al agua adherida al plumaje de tres especies de aves marinas: dos aves que bucean usando las alas y con carga alar grande, Ptychoramphus aleuticus y Synthliboramphus hypoleucus; y una especie que forrajea en la superficie del mar, con carga alar baja, Oceanodroma leucorhoa (incluida sólo en la parte del vuelo). Se encontró que las plumas mojadas ventralmente de los dos álcidos resisten una presión de aire máxima de 1.25 kPa. Las plumas de S. hypoleucus resistieron una presión de penetración de agua de 1.44 kPa, mientras que para P. aleuticus resistieron 1.36 kPa. Se evaluó el efecto del agua en el plumaje con relación a la habilidad de despegue de S. hypoleucus, P. aleuticus y O. leucorhoa. El plumaje de los álcidos retuvo menos agua que el de O. leucorhoa (~6.7% de la masa del cuerpo mb vs. 9.5%). La evaluación del despegue de estas tres especies, antes y después de mojar experimentalmente el plumaje, indica una reducción en la frecuencia de aleteo, velocidad, potencia por unidad de masa (media y máxima), energía mecánica por aleteo, pero un aumento en la aceleración. Durante el despegue, O. leucorhoa redujo su energía por unidad de masa y por aleteo en un 32%, mientras que para los álcidos fue ≤25%. El ángulo de despegue se redujo en los álcidos, pero no en O. leucorhoa. Los experimentos de carga máxima indican que O. leucorhoa soportó, con relación a mb, una carga extra del 45%, mientras tanto para P. aleuticus fue 23% y para S. hypoleucus fue 21%. La potencia máxima inducida fue 0.7 W para O. leucorhoa, 4.5 W para P. aleuticus y 5.7 W para S. hypoleucus. La habilidad de buceo fue evaluada incrementando experimentalmente el volumen de aire en los dos álcidos (16% más del contenido de aire original con un chaleco de polietileno de baja densidad), y se comparó con dos grupos control (sin carga y con un chaleco con flotabilidad neutra). Además, se cuantificó la pérdida de aire (burbujas) con respecto al tiempo. En ambas especies, los especimenes manipulados redujeron su velocidad de descenso, distancia y trabajo por aleteo en comparación con los controles. En P. aleuticus hubo diferencias significativas en el período de aleteo. En ambas especies no hubo ningún efecto en la pérdida de volumen de aire y en el costo de transporte entre grupos experimentales. Mientras que en las aves manipuladas fue al revés. El volumen de aire perdido por P. aleuticus y S. hypoleucus fue respectivamente de 9% y 8% del contenido original, durante el buceo a 0.7 m de profundidad. | Seabirds face unique tradeoffs between flying and diving, which are generally resolved according to their marine habitats and distinctive foraging modes. These tradeoffs are perhaps most pronounced in diving birds, which must not only contend with conflicting evolutionary pressures associated with flying but also with underwater swimming. Plumage wettability is an important factor in these tradeoffs as birds make transitions from air to water and vice versa. Dry plumage, which depends of feather microstructure, improves flying ability but increases buoyancy, which is a detriment to diving. The properties of wet feathers, and the effects of plumage wettability in flight and diving performance were analyzed in three seabird species: two wing propelled divers with high wing loading, Cassin’s Auklet (Ptychoramphus aleuticus) and Xantus’s Murrelet (Synthliboramphus hypoleucus); and Leach’s Storm-petrel (Oceanodroma leucorhoa), a surface feeder with low wing loading. I approached this issue by determining the mechanical costs of plumage wettability in takeoff and diving, both non-stationary modes of locomotion. Dry feathers did not resist any pressure for air penetration, but one-side wet feathers of both alcids resisted a critical air pressure of 1.25 kPa. Water pressure resistance of one-side wet feathers was 1.44 kPa for Xantus’s Murrelet and 1.36 kPa for Cassin’s Auklet. These results suggest that plumages with wet appearance reduce body heat loss during emersions after diving without losing their resistance to water penetration. Plumage wettability effect on takeoff performance was evaluated. The plumage of alcids held less water than that of the Storm-petrel (~6.7% of body mass vs. 9.5%). Examination of takeoff performance, both before and after experimentally submerging the birds, indicated that wingbeat frequency, speed and mass-specific power (peak and mean), and energy per wingbeat decreased in all species when plumage was experimentally wetted; whereas, mean acceleration increased. Leach’s Storm-petrel was more strongly affected by wet plumage than the alcids, with a 32% reduction in mass specific energy per wingbeat compared to ≤25% in the alcids. Takeoff angle was reduced in alcids, but not significantly so in O. leucorhoa. Mean maximum extra load supported by Leach’s storm petrels was 45% of body mass, 23% by Cassin’s Auklet, and 21% by Xantus’s Murrelet. Mean maximum induced power output was 0.7 W for Leach’s Storm-petrel, 4.5 W for Cassin’s Auklet, and 5.7 W for Xantus’s Murrelet. Diving performance was tested increasing experimentally the air volume (16% of the original content with a low density polyethylene vest) of Cassin’s Auklet and Xantus’s Murrelet, compared with two control groups (one non-manipulated and one with a neutral buoyancy vest). Also, the loss of air, as bubbles, with time was measured. Manipulated birds, loaded with an artificial air vest, reduced their descent speed, distance per flap, and work per flap compared with non-manipulated birds of both alcids. Significant differences were found in the flap duration of auklets only. In contrast, no difference was found in the loss of air volume and the cost of transport between experimental groups of both alcids. Non-manipulated birds presented a higher drag than buoyancy; meanwhile the contrary was found for manipulated birds. The air volume loss by Cassin’s Auklet and Xantus’s Murrelet measured during divings down to 0.7 m depth was 9% and 8% of the total air volume, respectively.