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Search Results: 1 - 10 of 735 matches for " URRUTIA; CISTERNAS "
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Comparación ambiental, mediante registros sedimentarios, entre las condiciones prehispánicas y actuales de un sistema lacustre
CISTERNAS,MARCO; TORRES,LAURA; URRUTIA,ROBERTO; ARANEDA,ALBERTO; PARRA,OSCAR;
Revista chilena de historia natural , 2000, DOI: 10.4067/S0716-078X2000000100014
Abstract: two moments of the environmental history of san pedro lacustrine system are compared through sedimentary, pollen and diatom records. the first one corresponds to the pre-hispanic period, representing the pristine conditions or background of the system. the second period, more recently, represents the human disturbance conditions during the late ten years. to achieve the above mentioned, sediment cores were collected from the bottom of two lakes that conform the san pedro lacustrine system (laguna grande and chica). chronological (c14), pollen and diatom analysis of superior and inferior layers of the cores were carried out. the results indicate that the san pedro lacustrine system has undergone drastic changes since spanish settlement. evolving from a natural vegetation, predominantly native, to an intense pressure of forestry use. in the same way, the qualitative water state presents a variation in its trophic features, showing a evolution from oligotrophic to eutrophic waters in laguna grande and from oligotrophic to mesotrophic in laguna chica. finally, it is suggested the incorporation of sedimentary records analysis in the study of environmental impact and management of lakes. in this way, it will be possible to know the background (the existing pre-hispanic conditions) and the response of aquatic ecosystem to the human influences
Comparación ambiental, mediante registros sedimentarios, entre las condiciones prehispánicas y actuales de un sistema lacustre Environmental comparison, through sedimentary records, between pre-Hispanic and current conditions of a lacustrine system
MARCO CISTERNAS,LAURA TORRES,ROBERTO URRUTIA,ALBERTO ARANEDA
Revista chilena de historia natural , 2000,
Abstract: Se comparan, a través de registros sedimentarios, palinológicos y diatomológicos, dos momentos de la historia ambiental del sistema lacustre de San Pedro. El primero, corresponde al periodo prehispánico, representando a las condiciones prístinas o línea base del sistema. El segundo periodo, el más reciente, representa aproximadamente a los últimos diez a os de intervención antrópica. Para lograr lo anterior, se recolectaron muestras verticales de sedimento del fondo en los dos lagos del sistema lacustre de San Pedro (Lagunas Grande y Chica). Se realizaron análisis cronológicos (C14), palinológicos y diatomológicos de los estratos superiores e inferiores de la columna sedimentaria. Los resultados indican que el sistema lacustre de San Pedro ha experimentado drásticos cambios desde la llegada de los espa oles, evolucionando desde una cobertura vegetacional natural, predominantemente nativa, a una fuerte presión de uso forestal. Del mismo modo, el estado cualitativo del agua presenta una variación en sus características tróficas, reconociéndose una evolución desde aguas oligotróficas a eutróficas, en Laguna Grande, y de oligotrofía a mesotrofía en Laguna Chica. Finalmente, se propone la incorporación del análisis de los registros sedimentarios en los estudios ambientales y planes de manejo de los sistemas lacustres. De esta forma será posible conocer la línea base (condiciones prehispánicas) y la respuesta del ecosistema acuático a las influencias antrópicas Two moments of the environmental history of San Pedro lacustrine system are compared through sedimentary, pollen and diatom records. The first one corresponds to the pre-Hispanic period, representing the pristine conditions or background of the system. The second period, more recently, represents the human disturbance conditions during the late ten years. To achieve the above mentioned, sediment cores were collected from the bottom of two lakes that conform the San Pedro lacustrine system (Laguna Grande and Chica). Chronological (C14), pollen and diatom analysis of superior and inferior layers of the cores were carried out. The results indicate that the San Pedro lacustrine system has undergone drastic changes since Spanish settlement. Evolving from a natural vegetation, predominantly native, to an intense pressure of forestry use. In the same way, the qualitative water state presents a variation in its trophic features, showing a evolution from oligotrophic to eutrophic waters in Laguna Grande and from oligotrophic to mesotrophic in Laguna Chica. Finally, it is suggested the incorporation of sedimenta
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
Evolución trófica de Laguna Grande de San Pedro (VIII Región, Chile) durante el último siglo, mediante el análisis de registros sedimentarios
CRUCES,FABIOLA; URRUTIA,ROBERTO; ARANEDA,ALBERTO; TORRES,LAURA; CISTERNAS,MARCO; VYVERMAN,WIM;
Revista chilena de historia natural , 2001, DOI: 10.4067/S0716-078X2001000200015
Abstract: this research reconstructs the trophic evolution of laguna grande de san pedro (viii region, chile) during the last century, through both the stratigraphic analyses of diatom remains and geochemical parameters preserved in a sediment core obtained in this lake. the results obtained show that the community of diatoms has changed its composition throughout time, showing four different periods, representing each one a distinctive trophic condition. on the other hand, the geochemical records increase their accumulation rates to the profile surface layers, making evident an increase of the productivity to the present time. in this context, it is possible to conclude that the productivity at laguna grande has experienced significant changes, evolving from an oligo-mesotrophic system (earlier period) to an eutrophic one (recent period). the most drastic changes would have happened during the last decades, as response to both the intense development of urbanization and forest activities in the basin of this lake
Suelos enterrados revelan la prehistoria sísmica del centro-sur de Chile durante los últimos dos milenios
Marco Cisternas
Revista de Geografía, Norte Grande , 2005,
Abstract: Se presentan las principales lecciones obtenidas durante tres a os de investigación paleosismológica en el centro sur de Chile. Gracias a estas claves, un equipo conformado por investigadores nacionales, nor-te americanos y japoneses, en el marco del proyecto Fondecyt No1020224 "Evidencias sedimentarias de eventos catastróficos naturales para la determinación de su periodicidad y riesgo", reconstruyeron la prehistoria de grandes terremotos y tsunamis ocurridos durante los últi-mos 2.000 a os en esta parte de Chile. Sobre la base de los resultados,se propone una nueva tasa de recurrencia para dichos eventos. Parale-lamente, se plantea una explicación a la enormidad del terremoto Chi-leno de 1960.
El terremoto de 1647 de Chile central como un evento intraplaca: otra amenaza para Chile metropolitano?
Marco Cisternas
Revista de Geografía, Norte Grande , 2012,
Abstract: El terremoto del 13 de mayo de 1647, la mayor catástrofe en la historia colonial de Chile central, es considerado como el segundo evento de la secuencia de terremotos interplaca que ha ocurrido con una sorprendente regularidad en esta parte de Chile. Sin embargo, el análisis histórico realizado sugiere que este terremoto, además de generar un enérgico y extenso sacudimiento en el valle central, no habría producido un tsunami. Ambas características podrían signifi car que se trató de un evento tipo intraplaca, originado superfi cialmente en la placa continental o profundo en la de Nazca. Los efectos reportados se asemejan más a los del terremoto de Chillán de 1939, un evento intraplaca de profundidad intermedia que aunque no produjo un tsunami generó grandes intensidades en el valle central y una enorme cantidad de víctimas. Si el terremoto de 1647 fue intraplaca, se plantea un problemático escenario de riesgo para la región más poblada del país.
The use of probiotics in gastrointestinal diseases
Daniel Cisternas
Medwave , 2011,
Abstract:
LA INVESTIGACIóN SOBRE FORMACIóN DOCENTE EN CHILE. TERRITORIOS EXPLORADOS E INEXPLORADOS
Tatiana Cisternas
Calidad en la Educación , 2011,
Abstract: Despite the strength shown by the debate about teacher preparation in recent years, research aimed to study the initial and continuing training of teachers is presented as a poorly explored dimension in the national scenario. Which are the research characteristics in this field? This article synthesizes some of the findings of a doctoral research work aimed at setting the features of objects that it problematizes and studies. From 82 summaries of research made between 1996 and 2007, it seems that all the studies of teacher education in Chile explore some items more than others and tend to build one-dimensional problems, that is to say they approach thephenomenon of formation only from one perspective of components.Keyword: research, teacher training, study objects, meta analysis
Habitat overlap of Paralabrax humeralis (Cuvier & Valenciennes, 1828), Hemilutjanus macrophthalmos (Tschudi, 1845), and Acanthistiuspictus (Tschudi, 1845) (Pisces; Serranidae) in the rocky subtidal south of Iquique, Chile
Cisternas,Félix; Sielfeld,;
Latin american journal of aquatic research , 2008,
Abstract: a simple scuba diving survey was used to study the habitat use and coexistence of three species in the family serranidae with sympatric distribution patterns along the rocky subtidal south of iquique. depth and microhabitat were recorded for each sampled individual. samples were taken at 15 different beaches through scuba diving in the deepest areas of the first rocky fringe, herein referred to as the transi-tion zone. the data were analyzed according to depth and frequency of use (microhabitat, habitat) for each species and considering three size classes. dendograms were created to interpret the similarities in the use of beaches, microhabitat, and habitat. the results showed the species to be independent in their use of the micro-habitat and habitat. the most abundant species was the roving paralabrax humeralis whose habitat was mostly associated with lessonia trabeculata. hemiluthjanus macrophthalmos and acanthistius pictus are cavity specialists, although their microhabitat use differed according to the size of the cavity: h. macrophthalmos occupied larger caves (> 0.5 m) and a. pictus mostly smaller cavities (< 0.5 m). the lack of juvenile a. pictus individuals seems to indicate the use of an alternative ecosystem. the distribution patterns of these serranids varied throughout the study area, indicating a dependence on the geomorphology of the substrate and the pres-ence of the structural species l. trabeculata.
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