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Search Results: 1 - 10 of 2204 matches for " KARLA POZO "
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Paleolimnological studies of Laguna Chica of San Pedro (VIII Region): Diatoms, hydrocarbons and fatty acid records Estudio Paleolimnológico de Laguna Chica de San Pedro (VIII Región): Diatomeas, hidrocarburos y ácidos grasos
ROBERTO URRUTIA,SABBE KOEN,FABIOLA CRUCES,KARLA POZO
Revista chilena de historia natural , 2000,
Abstract: Diatom, hydrocarbons and fatty acid sedimentary records were used for reconstructing the recent (last 150 years) palaeolimnological history of Laguna Chica of San Pedro (Concepción, VIII Región, Chile). Cluster analyses (Constrained Incremental Sum of Squares) on the diatom data revealed three distinct periods. The first period (1883-1940's) showed a pronounced increase in sedimentation rate and a slight increase in organic matter accumulation. In this period, eutrophic species (Aulacoseira granulata and Staurosira construens) became increasingly dominant. From the 1940s until the 1970s the diatom signal is more equivocal: after the initial decrease in the relative abundance of A. granulata and S. construens their numbers fluctuate without a clear pattern. Sedimentation rates strongly fluctuate in this period. From 1978 onwards eutrophic species are in decline while indicators of oligotrophic conditions, such as Cyclotella stelligera and Aulacoseira distans, become more abundant. This shift in the lake trophic status could not be attributed to a reduction in the nutrient load from the catchment and we hypothesize that the invasion of the lake by the submersed macrophyte Egeria densa has altered nutrient availability to the plankton communities. This is in agreement with the hydrocarbons and fatty acid analyses which demonstrate a shift in carbon number distributions from short chain alkanes and alkanoic acids (typical for microalgae) to long chain molecules (characteristic for higher plants) in the upper layers of the lake sediment Se realizó la reconstrucción histórica de los últimos 150 a os de Laguna Chica de San Pedro (Concepción, VIII Región, Chile), a través de la utilización de los restos de diatomeas, hidrocarburos y ácidos grasos contenidos en la columna de sedimento. El análisis estratigráfico de las diatomeas reveló la presencia de tres períodos diferentes. El primer período (1883-1940's), mostró un marcado aumento de las tasas de sedimentación y un leve aumento en la acumulación de materia orgánica; en este período se registra un incremento de las especies eutróficas (Aulacoseira granulata y Staurosira construens). Desde los a os cuarenta hasta la década del setenta el cambio en la comunidad de diatomeas fue más evidente y las tasas de sedimentación variaron fuertemente. A partir de 1978 disminuyen las especies eutróficas y aumentan las indicadoras de condiciones oligotróficas (Cyclotella stelligera y Aulacoseira distans). El cambio en el estado trófico del lago, no se atribuye a una reducción de los aportes de nutrientes desde la cuenca, si
PLAGUICIDAS ORGANOCLORADOS PERSISTENTES EN SEDIMENTOS DE TRES LAGOS COSTEROS Y UN LAGO ANDINO DE CHILE CENTRAL
RICARDO BARRAL,KARLA POZO,URRUTIA ROBERTO,MARCO CISTERNAS
Boletín de la Sociedad Chilena de Química , 2001,
Abstract: Se evaluó la presencia y distribución de los compuestos orgánicos persistentes (COPs) en núcleos de sedimentos de los lagos Chica y Grande de San Pedro, Lleu-Lleu e Icalma. Los compuestos fueron extraídos mediante sistema soxhlet con solvente n-hexano, la identificación y cuantificación, de estos, se realizó por cromatografía gaseosa con detector de captura de electrones de 63Ni. Se realizó un análisis estadístico de componentes principales (ACP) y Correlación de Pearson. Los plaguicidas identificados en los sedimentos fueron: a-HCH, g-HCH, Heptacloro, Aldrin, Endrin, pp′-DDT, pp'-DDE y pp'-DDD. Los resultados indican variaciones en la distribución y concentración de los COPs, al comparar los lagos urbanos con los lagos prístinos. Destaca la presencia de pp'-DDE (rango: b.n.d- 1.68 ng g-1 peso seco) y pp'-DDT (rango: b.n.d- 0.89 ng g-1 peso seco) en tres de los cuatro cuerpos de agua analizados. El análisis estadístico identificó correlaciones significativas entre el pp'-DDE y pp'-DDD. No se detectaron correlaciones entre el pp'-DDT y sus metabolitos. El ACP permitió agrupar algunos compuestos orgánicos en función de sus concentraciones y degradación a través del tiempo. Se concluye que Laguna Chica de San Pedro presentó las concentraciones más altas de COPs, las cuales son bajas al ser comparadas con concentraciones detectadas en áreas limpias del Sur de Chile We have measured concentrations and distribution of Persistent Organic Compounds (POC) in sediment cores from four Chilean lakes: Laguna Chica de San Pedro, Laguna Grande de San Pedro, Lleu-lleu, and Icalma. The organochlorine compounds were extracted with n-hexane in a soxhlet system and then identified and quantified by gas chromatography using a 63 Ni Electron Capture Detector. Statistical analyses were performed using a Principal Components Analysis (PCA) and the Pearson Correlation. The following pesticides were identified in the sediments: a-HCH, Lindane, Heptachlor, Aldrin, pp'-DDT, pp'-DDE, and pp'-DDD. The results show variation in both POC distribution and concentration when comparing pristine and urban lakes. It is important to note that pp'-DDE (range:b.d.l.-1.68 ng g-1 d.w.) and pp'-DDT (range: b.d.l.-0.89 ng g-1 d.w.) were present in three of the four lakes in the study. The statistical analyses showed significant correlations between pp'-DDE and pp'-DDD. Correlations between pp'-DDT and its metabolites were not detected. The PCA showed groupings of some of the organic compounds based on concentration and degradation over time. It is concluded that Laguna Chica de San Pedro is the l
PLAGUICIDAS ORGANOCLORADOS PERSISTENTES EN SEDIMENTOS DE TRES LAGOS COSTEROS Y UN LAGO ANDINO DE CHILE CENTRAL
BARRAL,RICARDO; POZO,KARLA; ROBERTO,URRUTIA; CISTERNAS,MARCO; PACHECO,PATRICIA; FOCARDI,S.;
Boletín de la Sociedad Chilena de Química , 2001, DOI: 10.4067/S0366-16442001000200008
Abstract: we have measured concentrations and distribution of persistent organic compounds (poc) in sediment cores from four chilean lakes: laguna chica de san pedro, laguna grande de san pedro, lleu-lleu, and icalma. the organochlorine compounds were extracted with n-hexane in a soxhlet system and then identified and quantified by gas chromatography using a 63 ni electron capture detector. statistical analyses were performed using a principal components analysis (pca) and the pearson correlation. the following pesticides were identified in the sediments: a-hch, lindane, heptachlor, aldrin, pp'-ddt, pp'-dde, and pp'-ddd. the results show variation in both poc distribution and concentration when comparing pristine and urban lakes. it is important to note that pp'-dde (range:b.d.l.-1.68 ng g-1 d.w.) and pp'-ddt (range: b.d.l.-0.89 ng g-1 d.w.) were present in three of the four lakes in the study. the statistical analyses showed significant correlations between pp'-dde and pp'-ddd. correlations between pp'-ddt and its metabolites were not detected. the pca showed groupings of some of the organic compounds based on concentration and degradation over time. it is concluded that laguna chica de san pedro is the lake with the highest concentration of poc's, although the levels appear low when compared with those measured in pristine areas in southern chile
Paleolimnological studies of Laguna Chica of San Pedro (VIII Region): Diatoms, hydrocarbons and fatty acid records
URRUTIA,ROBERTO; KOEN,SABBE; CRUCES,FABIOLA; POZO,KARLA; BECERRA,JOSE; ARANEDA,ALBERTO; VYVERMAN,WIM; PARRA,OSCAR;
Revista chilena de historia natural , 2000, DOI: 10.4067/S0716-078X2000000400014
Abstract: diatom, hydrocarbons and fatty acid sedimentary records were used for reconstructing the recent (last 150 years) palaeolimnological history of laguna chica of san pedro (concepción, viii región, chile). cluster analyses (constrained incremental sum of squares) on the diatom data revealed three distinct periods. the first period (1883-1940's) showed a pronounced increase in sedimentation rate and a slight increase in organic matter accumulation. in this period, eutrophic species (aulacoseira granulata and staurosira construens) became increasingly dominant. from the 1940s until the 1970s the diatom signal is more equivocal: after the initial decrease in the relative abundance of a. granulata and s. construens their numbers fluctuate without a clear pattern. sedimentation rates strongly fluctuate in this period. from 1978 onwards eutrophic species are in decline while indicators of oligotrophic conditions, such as cyclotella stelligera and aulacoseira distans, become more abundant. this shift in the lake trophic status could not be attributed to a reduction in the nutrient load from the catchment and we hypothesize that the invasion of the lake by the submersed macrophyte egeria densa has altered nutrient availability to the plankton communities. this is in agreement with the hydrocarbons and fatty acid analyses which demonstrate a shift in carbon number distributions from short chain alkanes and alkanoic acids (typical for microalgae) to long chain molecules (characteristic for higher plants) in the upper layers of the lake sediment
La economía global de la imagen
Pozo,Patricio;
ARQ (Santiago) , 2001, DOI: 10.4067/S0717-69962001004900018
Abstract: patricio pozo dissects a group of new scenarios that constitute and configure the new territory of images, superimposed to reality. figures of the everyday are translated until the exhaustion into two-dimension surface trying to represent, to support and to transmit a transactional world. a new race of designers -no longer anonymous artisans but visual authors of texts and interpreters of contents- will be in charge of managing and organizing this new scene
La economía global de la imagen
Patricio Pozo
ARQ , 2001,
Abstract: Un conjunto de nuevos escenarios que constituyen y configuran el nuevo territorio, superpuesto a la realidad, de las imágenes. Figuras cotidianas traducidas hasta el cansancio en dos dimensiones buscando representar y transmitir una globalidad transable. Una nueva raza de dise adores, ya no artesanos anónimos sino autores visuales de textos e intérpretes de contenidos, será la encargada de manejar y diagramar esta nueva escena Patricio Pozo dissects a group of new scenarios that constitute and configure the new territory of images, superimposed to reality. Figures of the everyday are translated until the exhaustion into two-dimension surface trying to represent, to support and to transmit a transactional world. A new race of designers -no longer anonymous artisans but visual authors of texts and interpreters of contents- will be in charge of managing and organizing this new scene
Conselho editorial, estatiística e nominata
Hamilton Pozo
Revista da Micro e Pequena Empresa , 2011,
Abstract:
Editorial
Hamilton Pozo
Revista da Micro e Pequena Empresa , 2011,
Abstract:
Editorial
Hamilton Pozo
Revista da Micro e Pequena Empresa , 2011,
Abstract:
Editorial
Hamilton Pozo
Revista da Micro e Pequena Empresa , 2011,
Abstract:
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