Quimica ambiental

En este trabajo se presenta un estudio de los efectos fotolíticos en cámara de ambiente controlado y la formación y reacción del ozono en presencia de diferentes contaminantes y espectros de radiación. Ya que el humo y la contaminación provocada principalmente por el Dióxido de azufre procedente del combustóleo que se quemaba en las industrias, el carbón que se usa en las carboeléctricas, y las emisiones de vehículos automotores, son la principal causa

La exposicion a humo ambiental en lugares cerrados es peligrosa para la salud. Las particulas de hasta 2,5 micras son marcadores del humo en los lugares cerrados. Este estudio monitoreo la calidad de aire en 4 locales gastronomicos de Asuncion, Paraguay, y algunas condiciones que influyen en los niveles de exposicion explorados. Los niveles mas altos de particulas encontrados fueron 9,9 μg/m3. En ninguno de los locales estudiados se detectaron fumadores. Falta mayor investigacion sobre contaminacion del aire en lugares cerrados para una mejor proteccion de la salud.

The present work aimed to evaluate the efficiency of an agro-industrial waste biosorbent in the removal of real textile wastewater. A model sample with methylene blue and remazol golden yellow at equimolar proportions was prepared to be treated with in natura, carbonized, and activated lemon peel beads. Activated biosorbent demonstrated superior capacity and removal rates. Characterization analyses investigated the morphology and physico-chemical properties of the biomaterial. The pH (2.0) and dosage (1.6 g.L-1) studies were carried out to select parameters for further studies. In kinetic assays, methylene blue equilibrium was reached faster than remazol golden yellow RNL. The analyses of fitting parameters indicated Elovich kinetic model to describe biosorption of the yellow dye while pseudo-first-order fit best to the blue dye biosorption data. The intraparticle diffusion model indicated that more than one step may limit biosorption kinetics. In the treatment of real textile waste...

La calidad del aire en las zonas aledañas a los puertos requiere un monitoreo permanente y cualificado de un conjunto de variables que sirven para calificar los riesgos asociados a las diversas actividades que allí se realizan. La normativa ambiental vigente en Colombia establece topes admisibles para los contaminantes atmosféricos, los cuales se consideran valores de referencia para definir, junto con las variables mencionadas, unos indicadores ambientales adecuados. Este artículo presenta la propuesta entregada, en diciembre de 2009, al Ministerio de Ambiente, Vivienda y Desarrollo Territorial, para la implementación de un Sistema de Vigilancia de la calidad del aire en puertos marítimos y sus áreas de influencia. La propuesta hace parte de un estudio más amplio de seguimiento ambiental permanente en varias áreas portuarias marítimas de Colombia.

O formaldeído é uma substância agressiva ao meio ambiente devido sua alta toxicidade e volatilização. Nesse sentido, o objetivo deste trabalho foi caracterizar o resíduo de formol do IFC Araquari, bem como isolar microrganismos com potencial para tratamento biológico deste resíduo, a partir de lodo ativado da ETE do município de Jaraguá do Sul-SC. A caracterização revelou um resíduo com pH ácido e baixos teores de sólidos totais. Também foram isoladas espécies fúngicas com potencial para a degradação de formaldeído, podendo ser utilizada em ensaios de tratamento biológico, podendo contribuir para a minimização dos impactos causados por esse passivo ambiental no Campus.

Los convertidores catalíticos son componentes clave en la reducción de emisiones contaminantes, transformando gases nocivos en sustancias menos dañinas. Sin embargo, su rendimiento puede verse comprometido por la acumulación de depósitos y residuos. Los aditivos juegan un papel esencial al mantener el convertidor limpio, prolongando su vida útil y asegurando su funcionamiento óptimo.
Además, el uso de aditivos contribuye a cumplir con las normativas ambientales, lo que subraya su relevancia en la protección del medio ambiente y la mejora del rendimiento vehicular.

The present work aimed to evaluate the efficiency of an agro-industrial waste biosorbent in the removal of real textile wastewater. A model sample with methylene blue and remazol golden yellow at equimolar proportions was prepared to be treated with in natura, carbonized, and activated lemon peel beads. Activated biosorbent demonstrated superior capacity and removal rates. Characterization analyses investigated the morphology and physico-chemical properties of the biomaterial. The pH (2.0) and dosage (1.6 g.L-1) studies were carried out to select parameters for further studies. In kinetic assays, methylene blue equilibrium was reached faster than remazol golden yellow RNL. The analyses of fitting parameters indicated Elovich kinetic model to describe biosorption of the yellow dye while pseudo-first-order fit best to the blue dye biosorption data. The intraparticle diffusion model indicated that more than one step may limit biosorption kinetics. In the treatment of real textile waste...

In the present work, aqueous cyanide has been eliminated by addition of H 2 O 2 as oxidant agent, and by heterogeneous photocatalysis with titanium oxide activated with UV radiation. The titanium oxide was synthesized by Sol-Gel method and Atrane route, it was characterized by X-ray Diffraction, Physical adsorption of gas N 2 , Spectroscopy of Reflectance Diffuse UV-vis, Electronic Microscopy of Transmission. It was evaluated the effect of hydrogen peroxide quantity (%V H2O2 /V CN-0.1; 0.5; 1.0 and 3.0 %) for CNelimination. The titanium oxide presents a high activity due its own structure-property relation: anatase crystalline phase, adequate crystalline microdomine sizes and high area superficial. Independent systems were evaluated for cyanide elimination: CN-UV, CN-UV/H 2 O 2 y CN-UV/TiO 2. Finally, a combined system CN-UV/H 2 O 2 /TiO 2 was tested, which presents the faster elimination of cyanide compared with the independent systems.

Pesticide residues in food are a threat to consumption. However, detecting residues quickly and directly on the sample is a complex job. In this work, the potential application of the Laser Induced Breakdown Spectroscopy (LIBS) technique for the rapid measurement of pesticide residues (imidacloprid, cypermethrin and chlorpyrifos) in chard leaves is explored by registering the chlorine emission line (725.66 nm). Significant differences can be observed with respect to the control sample, evidencing the applicability of this technique as a potential tool for the study of pesticide residues in food matrices.

La Ingeniería Industrial ha sido una de las carreras que más cambios ha tenido desde su creación en 1911. Según Charles Buxton Going, unos de los primeros autores en realizar una definición, la Ingeniería Industrial nació como “un área del conocimiento con elementos que incorporan campos y ciencias previas como ingeniería mecánica, sociología, sicología, filosofía y contabilidad que fusionadas generan una nueva y distinguible ciencia aplicada, la cual no consiste solamente en la dirección comercial o financiera, o solo en manejar plantas generadoras o maquinaria, ni solo en diseñar procesos y métodos, sino en coordinar todas estas actividades con otras en la dirección del trabajo, en actividades operacionales, usando el equipamiento proveído por otros ingenieros, arquitectos y fabricantes de maquinaria, en un ciclo de operaciones que inicia convirtiendo dinero en materias primas y mano de obra para generar un producto o servicio, el cual se revierte de nuevo en dinero con un margen ...

Agricultural soils were collected at 300 m away from Industrial City Xicohtencatl I, Tlaxcala. To evaluate by sequence of extraction the fraction of copper, iron, manganese, zinc and the associated to carbonates; organic matter and sulfides to oxides and hydroxides of iron and manganese, and residual fraction. Each soil were determined its pH, electrical conductivity, cation exchange capacity, organic matter, texture, nitrogen, phosphorus, potassium, calcium and magnesium. The results revealed that soils contain low concentration of organic matter, clay, cation exchange capacity and showed no salinity problems. The extraction sequence indicated that the iron and zinc are associated with the residual fraction, the manganese to oxides and hydroxides of iron and manganese; copper is presented interchangeably and associated to carbonates in higher concentration.

Se ha llevado a cabo un estudio experimental y de modelado cinético de la oxidación a alta presión (20-60 bar) de dimetil éter y etanol. Se ha analizado la influencia de variables como la estequiometría, temperatura y presión en la conversión de ambos compuestos oxigenados, así como en la formación de los principales productos.

En este trabajo se presentan los resultados de la comparación del micromaquinado láser de obleas de silicio empleando la técnica de escritura directa (direct writing) con pulsos de nanosegundos generados por la técnica de Q-switch en Nd:YAG y pulsos de femtosegundos, provenientes del Ti:Zafiro mode lockeado. Se determinaron los efectos de la redeposición de escombros (debris) y se proponen técnicas para su control.

In the present work, aqueous cyanide has been eliminated by addition of H 2 O 2 as oxidant agent, and by heterogeneous photocatalysis with titanium oxide activated with UV radiation. The titanium oxide was synthesized by Sol-Gel method and Atrane route, it was characterized by X-ray Diffraction, Physical adsorption of gas N 2 , Spectroscopy of Reflectance Diffuse UV-vis, Electronic Microscopy of Transmission. It was evaluated the effect of hydrogen peroxide quantity (%V H2O2 /V CN-0.1; 0.5; 1.0 and 3.0 %) for CNelimination. The titanium oxide presents a high activity due its own structure-property relation: anatase crystalline phase, adequate crystalline microdomine sizes and high area superficial. Independent systems were evaluated for cyanide elimination: CN-UV, CN-UV/H 2 O 2 y CN-UV/TiO 2. Finally, a combined system CN-UV/H 2 O 2 /TiO 2 was tested, which presents the faster elimination of cyanide compared with the independent systems.

In the present work, aqueous cyanide has been eliminated by addition of H 2 O 2 as oxidant agent, and by heterogeneous photocatalysis with titanium oxide activated with UV radiation. The titanium oxide was synthesized by Sol-Gel method and Atrane route, it was characterized by X-ray Diffraction, Physical adsorption of gas N 2 , Spectroscopy of Reflectance Diffuse UV-vis, Electronic Microscopy of Transmission. It was evaluated the effect of hydrogen peroxide quantity (%V H2O2 /V CN-0.1; 0.5; 1.0 and 3.0 %) for CNelimination. The titanium oxide presents a high activity due its own structure-property relation: anatase crystalline phase, adequate crystalline microdomine sizes and high area superficial. Independent systems were evaluated for cyanide elimination: CN-UV, CN-UV/H 2 O 2 y CN-UV/TiO 2. Finally, a combined system CN-UV/H 2 O 2 /TiO 2 was tested, which presents the faster elimination of cyanide compared with the independent systems.

Se diseñó, construyó y comprobó la aplicabilidad de un Índice de Evaluación Ambiental de Ecosistemas Acuáticos (IEAEA) basado en calidad físicoquímica, contenido de contaminantes en agua y sedimentos. Los criterios de calidad se fundamentan en investigaciones recientes y ...

Las coníferas son un grupo de plantas gimnospermas que forman extensos bosques, principalmente en el hemisferio norte, por lo que presentan importantes contribuciones ecológicas y económicas. Debido al tipo de suelos en los que suelen crecer las coníferas, estas plantas han desarrollado una gran tolerancia al amonio, muchas coníferas son capaces de usarlo como su principal fuente de nitrógeno inorgánico. El pino marítimo (Pinus pinaster Aiton) es una conífera distribuida por el Mediterráneo occidental que ha sido utilizada en tareas de reforestación, estabilización de suelos e industrialmente para la obtención de madera y resina. En los últimos años, esta conífera ha sido objeto de múltiples estudios genéticos y ómicos, obteniéndose importantes herramientas para su estudio.

Existe preocupación por el impacto antropogénico sobre el ecosistema Antártico, por tal motivo el Instituto del Mar del Perú realizó las expediciones científicas Vigésimo Quinta y Sexta del Perú hacia la Antártica.  Las investigaciones se llevaron a cabo en el verano austral 2018-2019 a bordo del buque BAP Carrasco en la ensenada Mackellar ubicada en la Isla Rey Jorge, en la cual se tomaron muestras de agua y sedimento marino en 11 estaciones de muestreo para la evaluación de metales traza (Cu, Zn, As y Pb) mediante espectrometría de masas por plasma acoplado inductivamente (ICP-MS). Se observó que los mayores niveles de concentración de Cu, As y Pb en matriz agua correspondieron al año 2019, en comparación con el año 2018. Asimismo, estos metales, no superaron los Estándares de Calidad Ambiental (ECA), por lo que se considera que aún no hay riesgos de contaminación acuática. Sin embargo, hay una tendencia de incremento de concentración de estos metales cada año.  Por otro lado, las...

No methods are recommended for first action since last year's report. The following topics are to be discontinued because these studies were finished and the methods were recommended for final action: Filth in Cheeses, Alternative Sieving Method; Light Filth in Fish Paste and Sauces Containing Soy Sauce, Thickeners, and Spices by Flotation; Light Filth in Soybean Curd by Flotation; and Mammalian Feces in Spices by Chemical Detection. As noted in last year's General Referee report, there is an urgent need to develop alternatives to the use of CC1 4 for detection of heavy filth in methods 968.33, Filth in Shelled Nuts; 978.21, Heavy Filth in Capsicums (Ground), Sedimentation Method; 988.16, Filth in Ground Coffee and Coffee Substitutes, Sedimentation and Flotation Method; 972.40, Light Filth in Pepper. All these methods use CC1 4 to separate heavy filth, i.e., sand and grit, from plant tissues. It is recommended that AOAC continue to make an effort to recruit members to develop alternatives for the use of CC1 4 in these methods. Because the following methods require the use of either CHC1 3 or CCI4, they are not recommended for final action: 970.68 Heavy Filth in Tea, Sedimentation Method 965.40 Filth in Spices 975.48 Heavy and Light Filth in Spices and Condiments, Flotation Method 968.38 Filth in Cinnamon (Ground) 945.84 Excreta (Rodent and Insect) in Condiment Seeds 975.50 Filth in Garlic Powder and Ground Onion 979.25 Light Filth in Sage (Rubbed) 970.74 Foreign Mater in Drugs (Leafy, Crude) 941.16 Filth in Grain Products 972.36 Light Filth in High Bran Content Breads 972.37 Light Filth in Baked Goods with Fruit and Nut Tissues. In addition to the above methods, the following methods are not recommended for final action for the reasons listed: 945.82 Light Filth in Broccoli (Canned) is not recommended for final action because it uses lead acetate. 972.41 Urine on Grain, Urease Bromothymol Blue Agar Test is not recommended for final action at this time because Associate Referee Patricia Valdes in currently working on a modification of the method. 980.28 Urine Stains on Foods and Containers, Thin Layer Chromatographic Method is not recommended for Final Action because it requires the use of benzene. Methods 950.94 Light Filth (Pre-and Post-Milling) in Baked Goods with Fruit and Nut Tissues Pancreatin Digestion Flotation Method; 945.77 Filth in Apple Chops (Dried); 945.83 Filth in Spices (Whole), 972.58 Light and Heavy Filth in Pep

espanolEl objetivo de este articulo fue evidenciar convergencias y divergencias en la formacion de profesores de fisica en Chile y Finlandia. Si bien el estudio es mas amplio, en esta ocasion se ha realizado un analisis comparativo cualitativo de las mallas curriculares de dos universidades emblematicas de cada pais. Concluimos senalando algunas consideracion y sugerencia sobre la adaptacion del modelo finlandes al contexto nacional como tambien algunas reflexiones en torno a la formacion de profesores de fisica. EnglishThe objective of this article was convergences and divergences in the training of physics teachers in Finland and Chile. Although this study is more extensive, a qualitative comparative analysis of teacher training curriculum of two emblematic universities in each country has been carried out this time. We concluded by pointing out some considerations and suggestions on adaptation the Finnish model to our national context, as well as some reflections on the physics t...

En este trabajo se presentan los resultados de la comparación del micromaquinado láser de obleas de silicio empleando la técnica de escritura directa (direct writing) con pulsos de nanosegundos generados por la técnica de Q-switch en Nd:YAG y pulsos de femtosegundos, provenientes del Ti:Zafiro mode lockeado. Se determinaron los efectos de la redeposición de escombros (debris) y se proponen técnicas para su control.

En este trabajo se presentan los resultados de la comparación del micromaquinado láser de obleas de silicio empleando la técnica de escritura directa (direct writing) con pulsos de nanosegundos generados por la técnica de Q-switch en Nd:YAG y pulsos de femtosegundos, provenientes del Ti:Zafiro mode lockeado. Se determinaron los efectos de la redeposición de escombros (debris) y se proponen técnicas para su control.

In the present work, aqueous cyanide has been eliminated by addition of H 2 O 2 as oxidant agent, and by heterogeneous photocatalysis with titanium oxide activated with UV radiation. The titanium oxide was synthesized by Sol-Gel method and Atrane route, it was characterized by X-ray Diffraction, Physical adsorption of gas N 2 , Spectroscopy of Reflectance Diffuse UV-vis, Electronic Microscopy of Transmission. It was evaluated the effect of hydrogen peroxide quantity (%V H2O2 /V CN-0.1; 0.5; 1.0 and 3.0 %) for CNelimination. The titanium oxide presents a high activity due its own structure-property relation: anatase crystalline phase, adequate crystalline microdomine sizes and high area superficial. Independent systems were evaluated for cyanide elimination: CN-UV, CN-UV/H 2 O 2 y CN-UV/TiO 2. Finally, a combined system CN-UV/H 2 O 2 /TiO 2 was tested, which presents the faster elimination of cyanide compared with the independent systems.

Resumo: O importante cenário que a indústria têxtil representa no Brasil insere um quadro de grande produção com consequente aumento de insumos e geração de resíduos, principalmente, os líquidos. Estes resíduos apresentam alta toxicidade e podem interferir em toda a ecologia do ambiente caso seja lançado inadvertidamente. A busca de novas tecnologias eficientes e com relação custo benefício boa é o foco da atualidade. Frente a isso, o uso de fungos na biorremediação de efluentes coloridos têm mostrado resultados promissores que norteiam a sua aplicação para o tratamento destes resíduos. O objetivo deste trabalho foi usar dois reatores em bateladas sequenciais, operados em série e inoculados com o fungo Phanerochaete chrysosporium para remoção de corante Vermelho do Congo, sob a influência da presença de glicose como cossubstrato, na concentração de 1g/L, no reator R1 e de 0,5g/L, no reator R2. Os reatores foram monitorados através da medição analítica do valor de pH, e das concentrações de corante, demanda química de oxigênio, amônia, nitrato e fósforo total. Foi realizada a atividade da enzima manganês peroxidase. Ao final de 10 ciclos estudados, registrou-se 95% de remoção global de corante, 80% de matéria orgânica, 76% para amônia, 88% para nitrato e 8% para fósforo total. A enzima manganês peroxidase se manteve em níveis basais no meio mineral apresentando valor médio de 2,6 µmol/min no reator R1 e 2,3 µmol/min no reator R2. A aplicação de reatores em série propiciou uma maior mineralização do corante e aumento da remoção percentual de amônia, nitrato e matéria orgânica, indicando assim a viabilidade do uso de reatores biológicos com fungos para o tratamento de efluentes têxteis.

DYE REMOVAL BY USE OF Aspergillus niger AN 400 IN A SEQUENTIAL BATCH REACTOR. A sequential batch reactor (4 L) inoculated with Aspergillus niger was operated in order to remove congo red dye (10 mg L-1). The feeding of the reactor was done to each 7 days. The glucose was added in the concentration of 1 g.L-1 (Stage I) and 0.5 g L-1 (Stage II). The Stage III occurred without glucose addition. The Stage I was great to process, because the system reached the greater dye removal (95%) as well as the kinetic parameters ware the best-K M (0.7 g L-1) and k 1 (0.025 h-1).

DYE REMOVAL BY USE OF Aspergillus niger AN 400 IN A SEQUENTIAL BATCH REACTOR. A sequential batch reactor (4 L) inoculated with Aspergillus niger was operated in order to remove congo red dye (10 mg L-1). The feeding of the reactor was done to each 7 days. The glucose was added in the concentration of 1 g.L-1 (Stage I) and 0.5 g L-1 (Stage II). The Stage III occurred without glucose addition. The Stage I was great to process, because the system reached the greater dye removal (95%) as well as the kinetic parameters ware the best-K M (0.7 g L-1) and k 1 (0.025 h-1).

Existe preocupación por el impacto antropogénico sobre el ecosistema Antártico, por tal motivo el Instituto del Mar del Perú realizó las expediciones científicas Vigésimo Quinta y Sexta del Perú hacia la Antártica.  Las investigaciones se llevaron a cabo en el verano austral 2018-2019 a bordo del buque BAP Carrasco en la ensenada Mackellar ubicada en la Isla Rey Jorge, en la cual se tomaron muestras de agua y sedimento marino en 11 estaciones de muestreo para la evaluación de metales traza (Cu, Zn, As y Pb) mediante espectrometría de masas por plasma acoplado inductivamente (ICP-MS). Se observó que los mayores niveles de concentración de Cu, As y Pb en matriz agua correspondieron al año 2019, en comparación con el año 2018. Asimismo, estos metales, no superaron los Estándares de Calidad Ambiental (ECA), por lo que se considera que aún no hay riesgos de contaminación acuática. Sin embargo, hay una tendencia de incremento de concentración de estos metales cada año.  Por otro lado, las...

El diseño y evaluación de un plan de estudios son actividades prioritarias para la habilitación y acreditación de programas. Al igual que en una cinta de Moebius, el currículo es el punto de partida, y a la vez el beneficiario, de las funciones misionales de docencia, investigación, proyección social e internacionalización. Sin embargo, en la mayoría de los casos éste no se construye y desarrolla a partir de la relación intricada de temas, conceptos y resultados de aprendizaje; buscando una superestructura que asegure tanto lo multidimensional, como el pensamiento crítico y la antinomia. En este contexto, la experiencia de aplicar un método heterodoxo basado en la complejidad y diagramado en mapas mentales y redes de conocimiento, permite obtener propuestas curriculares compactas y bien estructuradas. Método que ayudó en el logro de once procesos de renovación de registro calificado, dos acreditaciones y en cinco solicitudes exitosas de nuevos registros de programa en distintas universidades del país.

Recebido em 28/8/11; aceito em 1/12/11; publicado na web em 28/2/12 STUDY OF METAL CONTAMINATION IN AQUATIC SEDIMENTS OF THE BAY OF MATANZAS. Surface sediments of the Bay of Matanzas (Cuba) were studied to assess its environmental quality by using several criteria (metal content index, pollution load index and sediment quality guidelines). Two partial digestion sediment procedures and a modified BCR sequential extraction were used. The concentrations of metals were measured by atomic spectroscopy methods. The founded contents of Cu (2,4-27,9 mg kg-1), Zn (2,5-55,5 mg kg-1) and Ni (8,8-99,2 mg kg-1) were below those reported by other authors. The results obtained suggested that the most polluted sites were 3, 5, and 6. The sequential extraction procedure showed that most of the studied metals were associated to the more stable fractions.

Se presenta la evaluación del procedimiento de extracción secuencial aprobado por la BCR (BCR, por sus siglas en inglés, Community Bureau of Reference) para determinar metales en muestras de sedimentos del río Catatumbo, Venezuela. Las fracciones consistieron en 4 etapas: en la primera, llamada intercambiable, se extrajo utilizando ácido acético; la segunda, o reducible, con hidroxicloruro de amonio; la tercera, u oxidable, con peróxido de hidrógeno y acetato de amonio y la residual, que es la etapa remanente, se digirió con agua regia. El análisis se realizó por espectrometría de absorción atómica con llama (FAAS), horno de grafito (ETAAS) y espectrometría de emisión atómica con plasma inductivamente acoplado (ICP-AES). Los metales determinados fueron Pb y V. Las determinaciones por FAAS, ETAAS e ICP-AES indicaron que no hubo diferencias estadísticamente significativas (p < 0,05) cuando se compararon los resultados de 24 muestras de sedimentos del río Catatumbo realizadas por triplicado. La exactitud encontrada sumando las cuatro etapas de la BCR para Pb y V fueron comparables a los resultados obtenidos por digestión ácida, lo cual indica que el procedimiento es adecuado para la cuantificación de los metales estudiados. El Pb y V se encontró mayormente (55-97 %) en la etapa residual lo que los hace no disponibles.

Recebido em 28/8/11; aceito em 1/12/11; publicado na web em 28/2/12 STUDY OF METAL CONTAMINATION IN AQUATIC SEDIMENTS OF THE BAY OF MATANZAS. Surface sediments of the Bay of Matanzas (Cuba) were studied to assess its environmental quality by using several criteria (metal content index, pollution load index and sediment quality guidelines). Two partial digestion sediment procedures and a modified BCR sequential extraction were used. The concentrations of metals were measured by atomic spectroscopy methods. The founded contents of Cu (2,4-27,9 mg kg-1), Zn (2,5-55,5 mg kg-1) and Ni (8,8-99,2 mg kg-1) were below those reported by other authors. The results obtained suggested that the most polluted sites were 3, 5, and 6. The sequential extraction procedure showed that most of the studied metals were associated to the more stable fractions.

Zn are detd by atomic absorption spectrophotometry (AAS) after generation of metal hydrides (for As and Se). (Caurion: See safety notes on pipets, nitric acid, perchloric acid, sodium hydroxide, and arsenic tri0xide.) B. Apparatus (a) Polarograph.--With anodic stripping accessories. Typical operating parameters for Model 174 with hanging drop Hg electrode are: Scan rate, 5 mv/sec; scan direction, +; scan range, 1.5 v; initial potential, -0.7 v; modulation amplitude, 25 mv; operation mode, differential pulse; display direction, "--": drop time, 0.5 sec; low pass filter, off; selector, off; pushbutton, initial; output offset, off; and current range, 5-10 pamp, or as needed. N oxides are released.) Weigh 0.3 g sample (dry basis) into decontaminated decomposition vessel, add 5 mL HNO,, close vessel with lid, and heat in 150? oven 2 hr. Cool in hood, remove vessel from jacket, and transfer contents to 10 mL vol. flask. Add 4 mL HO to vessel, cover with lid, and while holding lid tightly agamst rim, invert several times, and add rinse to flask. Dil.

In Chile there are few studies describing the biological activities and soil nutrient dynamics in high mountain areas, therefore sensitive parameters able to express what happens in these ecosystems are required. The aim of this study was to determine soil biological properties through biochemical variables: fluorescein diacetate hydrolysis, carbon and nitrogen microbial biomass, β-glucosidase, carboximethylcellulase, acid phosphatase, urease and arylsulfatase; and chemical characteristics of soil in an altitudinal transect in Conguillío National Park (38º S), Chile. We investigated four forest communities from 1,140 to 1,700 m a.s.l.: Nothofagus antarctica, Nothofagus alpina with Nothofagus dombeyi, Araucaria araucana with Nothofagus pumilio and Nothofagus pumilio (Krummholz). Biochemical parameters were sensitive to changes in altitude, obtaining the highest biological activities (fluorescein diacetate hydrolysis, nitrogen microbial biomass, acid phosphatase, β-glucosidase) in N. alpina with N. dombeyi (74.9 μg fluorescein g-1 h-1 ; 50.3 mg N kg-1 ; 78.8 μmol p-nitrophenol g-1 h-1 ; 9.14 μmol p-nitrophenol g-1 h-1 , respectively) located at 1,250 m a.s.l. due to favorable climatic conditions, followed by N. antarctica and A. araucana with N. pumilio. The lowest levels of the biological activities are shown by N. pumilio (Krummholz) (23.7 μg fluorescein g-1 h-1 ; 3.1 mg N kg-1 ; 6.2 μmol p-nitrophenol g-1 h-1 ; 0.78 μmol p-nitrophenol g-1 h-1 , respectively) at 1,700 m a.s.l., located in restricted soil and climatic conditions.

En este artículo se aborda el desafío del diseño de un currículo orientado al logro de competencias. Para ello, se analizó el estado del arte mediante una revisión del concepto de competencia y de los modelos curriculares en este ámbito. De esta revisión no se ha encontrado un método formal que permita construir un currículo orientado a las competencias. Para cubrir esta brecha el presente trabajo propone una metodología cuyo punto de partida es asociar a cada competencia un módulo o una asignatura, asociación que puede ser modi cada por restricciones de tiempo y recursos a través de un proceso de re namientos sucesivos. La metodología propone las siguientes etapas a partir de un per l profesional especí co dado por sus competencias y capacidades asociadas: a) identi cación de los módulos; b) secuenciación de los módulos; c) estructuración de los módulos; d) revisión de los módulos; e) revisión del currículo, y f) construcción del syllabus. Bajo esta metodología los módulos que conforman el currículo apuntan a integrar los conocimientos y las habilidades requeridas para el logro de las competencias, antes que a fraccionarlos por disciplina.

The Cd and Pb spatial variations in coastal sediments and Polymesoda solida tissue of Lake Maracaibo (Venezuela) were investigated, emphasizing possible specific sources of pollution. Four samplings in 11 sites were made between October, 2009, and March, 2010. Metal was determined by atomic absorption spectroscopy with a graphite furnace, after acid digestion of the samples in high pressure pumps. Results show a significant spatial variability of Cd and Pb content, resulting from natural and anthropogenic phenomena. According to the concentrations, coastal sediments exhibited low values (0.243±0.193 mgCd/Kg dry weight and 4.117±5.259 mgPb/Kg dry weight), even below detection limits for the method (0.030 mgCd/Kg dry weight and 0.051 mgPb/Kg dry weight), in some cases. The clams (P. solida) (0.963±0.421mgCd/Kgdry weight and 6.053±8.958 mgPb/Kg dry weight) were not considered acceptable for human consumption, according to the maximum limits of tolerable weekly ingestion by body weight,...

Recebido em 9/6/05; aceito em 2/12/05; publicado na web em 14/6/06 MULTIRESIDUE METHOD FOR MONITORING ENVIRONMENTAL CONTAMINATION BY PESTICIDES IN THE BAURU REGION (SP) USING HONEY AS BIOINDICATOR. The presence of residues of the major groups of pesticides (organohalogen, organophosphorous, pyrethroids and organonitrogen) in representative samples of honey produced in Bauru (state of São Paulo, Brazil) was investigated from 1999 through2004. A multiresidue method was applied to honey samples to determine 48 pesticides with recoveries ranging from 76 to 95%. The limits of detection found were lower than 10 μg/kg for GC-MS-SIM. The results indicated that most pesticides found in the samples belonged to the organohalogen and organonitrogen groups. Residues of malathion were detected in almost all of the samples in high concentration.