117 research outputs found

    Revealing the last 13,500 years of environmental history from the multiproxy record of a mountain lake (Lago Enol, northern Iberian Peninsula)

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    This is the author's accepted manuscript. The final publication is available at Springer via http://dx.doi.org/10.1007/s10933-009-9387-7.We present the Holocene sequence from Lago Enol (43°16′N, 4°59′W, 1,070 m a.s.l.), Cantabrian Mountains, northern Spain. A multiproxy analysis provided comprehensive information about regional humidity and temperature changes. The analysis included sedimentological descriptions, physical properties, organic carbon and carbonate content, mineralogy and geochemical composition together with biological proxies including diatom and ostracod assemblages. A detailed pollen study enabled reconstruction of variations in vegetation cover, which were interpreted in the context of climate changes and human impact. Four distinct stages were recognized for the last 13,500 years: (1) a cold and dry episode that includes the Younger Dryas event (13,500–11,600 cal. year BP); (2) a humid and warmer period characterizing the onset of the Holocene (11,600–8,700 cal. year BP); (3) a tendency toward a drier climate during the middle Holocene (8,700–4,650 cal. year BP); and (4) a return to humid conditions following landscape modification by human activity (pastoral activities, deforestation) in the late Holocene (4,650–2,200 cal. year BP). Superimposed on relatively stable landscape conditions (e.g. maintenance of well established forests), the typical environmental variability of the southern European region is observed at this site.The Spanish Inter-Ministry Commission of Science and Technology (CICYT), the Spanish National Parks agency, the European Commission, the Spanish Ministry of Science, and the European Social Fund

    Revealing the last 13,500 years of environmental history from the multiproxy record of a mountain lake (Lago Enol, northern Iberian Peninsula)

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    This is the author's accepted manuscript. The final publication is available at Springer via http://dx.doi.org/10.1007/s10933-009-9387-7.We present the Holocene sequence from Lago Enol (43°16′N, 4°59′W, 1,070 m a.s.l.), Cantabrian Mountains, northern Spain. A multiproxy analysis provided comprehensive information about regional humidity and temperature changes. The analysis included sedimentological descriptions, physical properties, organic carbon and carbonate content, mineralogy and geochemical composition together with biological proxies including diatom and ostracod assemblages. A detailed pollen study enabled reconstruction of variations in vegetation cover, which were interpreted in the context of climate changes and human impact. Four distinct stages were recognized for the last 13,500 years: (1) a cold and dry episode that includes the Younger Dryas event (13,500–11,600 cal. year BP); (2) a humid and warmer period characterizing the onset of the Holocene (11,600–8,700 cal. year BP); (3) a tendency toward a drier climate during the middle Holocene (8,700–4,650 cal. year BP); and (4) a return to humid conditions following landscape modification by human activity (pastoral activities, deforestation) in the late Holocene (4,650–2,200 cal. year BP). Superimposed on relatively stable landscape conditions (e.g. maintenance of well established forests), the typical environmental variability of the southern European region is observed at this site.The Spanish Inter-Ministry Commission of Science and Technology (CICYT), the Spanish National Parks agency, the European Commission, the Spanish Ministry of Science, and the European Social Fund

    A multi-dating approach to age-modelling long continental records: The 135 ka El Cañizar de Villarquemado sequence (NE Spain)

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    We present the multidisciplinary dating approach - including radiocarbon, Uranium/Thorium series (U/Th), paleomagnetism, single-grain Optical Stimulated Luminescence (OSL), Infrared Stimulated Luminescence (IRSL) and tephrochronology - used for the development of an age model for the Cañizar de Villarquemado sequence (VIL) for the last ca. 135 ka. We describe the protocols used for each technique and discuss the positive and negative results, as well as their implications for interpreting the VIL sequence and for dating similar terrestrial records. In spite of the negative results of some techniques, particularly due to the absence of adequate sample material or inaccurate analytical precision, the multi-technique strategy employed here is essential to maximize the chances of obtaining robust age models in terrestrial sequences. The final Bayesian age model for VIL sequence includes 16 AMS 14C ages, 9 OSL ages and 5 previously published IRSL ages, and the accuracy and resolution of the model are improved by incorporating information related to changes in accumulation rate, as revealed by detailed sedimentological analyses. The main paleohydrological and vegetation changes in the sequence are coherent with global Marine Isotope Stage (MIS) 6 to 1 transitions since the penultimate Termination, although some regional idiosyncrasies are evident, such as higher moisture variability than expected, an abrupt inception of the last glacial cycle and a resilient response of vegetation in Mediterranean continental Iberia in both Terminations

    Clinical outcomes during anticoagulant therapy in fragile patients with venous thromboembolism.

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    Subgroup analyses from randomized trials suggested favorable results for the direct oral anticoagulants in fragile patients with venous thromboembolism (VTE). The frequency and natural history of fragile patients with VTE have not been studied yet. To compare the clinical characteristics, treatment and outcomes during the first 3 months of anticoagulation in fragile vs non-fragile patients with VTE. Retrospective study using consecutive patients enrolled in the RIETE (Registro Informatizado Enfermedad TromboEmbolica) registry. Fragile patients were defined as those having age ≥75 years, creatinine clearance (CrCl) levels ≤50 mL/min, and/or body weight ≤50 kg. From January 2013 to October 2016, 15 079 patients were recruited. Of these, 6260 (42%) were fragile: 37% were aged ≥75 years, 20% had CrCl levels ≤50 mL/min, and 3.6% weighed ≤50 kg. During the first 3 months of anticoagulant therapy, fragile patients had a lower risk of VTE recurrences (0.78% vs 1.4%; adjusted odds ratio [OR]: 0.52; 95% confidence intervals [CI]: 0.37-0.74) and a higher risk of major bleeding (2.6% vs 1.4%; adjusted OR: 1.41; 95% CI: 1.10-1.80), gastrointestinal bleeding (0.86% vs 0.35%; adjusted OR: 1.84; 95% CI: 1.16-2.92), haematoma (0.51% vs 0.07%; adjusted OR: 5.05; 95% CI: 2.05-12.4), all-cause death (9.2% vs 3.5%; adjusted OR: 2.02; 95% CI: 1.75-2.33), or fatal PE (0.85% vs 0.35%; adjusted OR: 1.77; 95% CI: 1.10-2.85) than the non-fragile. In real life, 42% of VTE patients were fragile. During anticoagulation, they had fewer VTE recurrences and more major bleeding events than the non-fragile

    A paleolimmological perspective of three karstic lake (taravilla, Zoñar and Estanya): Sedimentological and hydrogeological evolution climate and human impact and implications for management and restoration policies

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    Se resumen los datos disponibles y previamente publicados de sondeos sedimentarios recuperados en tres lagos kársticos españoles: Taravilla en el Sistema Ibérico (provincia de Guadalajara), Estanya en el Prepirineo aragonés (provincia de Huesca) y Zoñar en el valle del Guadalquivir (provincia de Córdoba). El intervalo temporal que abarcan estas secuencias sedimentarias varía desde el último máximo glacial (desde hace 21000 años en Estanya) hasta el Holoceno tardío (desde hace 4000 en Zoñar y 2000 años en Taravilla). Los resultados muestran la gran variabilidad de ambientes de depósito que se desarrollaron en estos sistemas lacustres, principalmente ligados a fluctuaciones en el nivel de los lagos, la química de las aguas y cambios en las cuencas de drenaje. Los cambios climáticos han sido los principales responsables de esta gran variabilidad sedimentológica e hidrológica. El impacto de las actividades humanas en las cuencas de recepción ha sido perceptible desde época ibero-romana, pero especialmente a partir de la Edad Media, con un claro aumento de las tasas de sedimentación en los lagos. Las secuencias lacustres representan archivos detallados de cambio global en el pasado que son imprescindibles para conocer tanto la variabilidad climática regional como la dinámica de estos sistemas y así implementar políticas de conservación y gestión de estos espacios naturales y de los recursos hidrológicos y ecológicos que sustentan y estrategias de adaptación al cambio climático.A paleolimnological perspective of three Spanish karstic lakes (Taravilla, Zoñar and Estanya): sedimentological and hydrological evolution, climate and human impact and implications for management and restoration policies. We synthesize the available, published paleolimnological information based on sediment core analyses from three Spanish karstic lakes: Taravilla in the Iberian Range (Guadalajara province), Estanya in the Pre-Prepirinean Range (Huesca province) and Zoñar in the Guadalquivir Basin (Córdoba province). The time span ranges from the last 21000 years in Estanya, about 4000 years in Zoñar and 2000 years in Taravilla. The multidisciplinary study shows large depositional changes in the lakes mostly related to water level and hydrochemical fluctuations and changes in the watershed. Climate change has been the main forcing to explain the hydrological changes in the lakes. Human impact in the watershed and the lakes has been documented since Iberian-Roman times and it has increased since the Medieval Ages with a much higher sediment delivery to the lakes. Lake sediment sequences contain detailed archives of global changes in the past, needed to understand the natural climate variability and the dynamics of the lacustrine systems. These data will help to implement conservation and restoration policies of aquatic ecosystems and also strategies for adaptation to future climate changes.Depto. de Geodinámica, Estratigrafía y PaleontologíaFac. de Ciencias GeológicasTRUEComisión Interministerial de Ciencia y TecnologíaDiputación General de Aragónpu

    Holocene climate variability, vegetation dynamics and fire regime in the central Pyrenees: the Basa de la Mora sequence (NE Spain)

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    High resolution multiproxy data (pollen, sedimentology, geochemistry, chironomids and charcoal) from the Basa de la Mora (BSM) lake sequence (42° 32′ N, 0° 19′ E, 1914 m a.s.l.) show marked climate variability in the central southern Pyrenees throughout the Holocene. A robust age model based on 15 AMS radiocarbon dates underpins the first precise reconstruction of rapid climate changes during the Holocene from this area. During the Early Holocene, increased winter snowpack and high snowmelt during summer, as a consequence of high seasonality, led to higher lake levels, a chironomid community dominated by non-lacustrine taxa (Orthocladiinae) related to higher inlet streams, and a forested landscape with intense run-off processes in the watershed. From 9.8 to 8.1 cal ka BP, climate instability is inferred from rapid and intense forest shifts and high fluctuation in surface run-off. Shifts among conifers and mesophytes reveal at least four short-lived dry events at 9.7, 9.3, 8.8 and 8.3 cal ka BP. Between 8.1 and 5.7 cal ka BP a stable climate with higher precipitation favoured highest lake levels and forest expansion, with spread of mesophytes, withdrawal of conifers and intensification of fires, coinciding with the Holocene Climate Optimum. At 5.7 cal ka BP a major change leading to drier conditions contributed to a regional decline in mesophytes, expansion of pines and junipers, and a significant lake level drop. Despite drier conditions, fire activity dropped as consequence of biomass reduction. Two arid intervals occurred between 2.9 and 2.4 cal ka BP and at 1.2–0.7 cal ka BP (800–1300 AD). The latter coincides with the Medieval Climate Anomaly and is one of the most arid phases of the Holocene in BSM sequence. Anthropogenic disturbances were small until 700 AD, when human pressure over landscape intensified, with Olea cultivation in the lowlands and significant deforestation in highlands. Colder and unfavourable weather conditions during the second part of the Little Ice Age caused a temporary cease of high-land management. The most intense anthropogenic disturbances occurred during the second half of 19th century. Last decades are characterized by recovery of the vegetation cover as a result of land abandonment, and lowered lake levels, probably due to higher temperatures
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