Ice Cores
Mostrando 1-12 de 17 artigos, teses e dissertações.
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1. Radionuclídeos como marcadores de um novo tempo: o Antropoceno
On May 2019, the members of the Anthropocene Working Group completed a binding vote to affirm some of the key questions that have been agreed in 2016: the Anthropocene should be considered as a formal chronostratigraphic unit, defined by a Global Boundary Stratotype Section and Point (GSSP), using one of the stratigraphic signals around the mid-twentieth cen
Quím. Nova. Publicado em: 2020-04
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2. Histórico da deposição de elementos traço na Bacia Amazônica Ocidental ao longo do século XX / Trace elements deposition history in the western Amazon Basin during the 20th century
Pendant le XX eme siécle plusieurs modifications importantes ont eu lieu dans l\ environement nature/ à cause du développement économique humain. Pour étudier l\ impact de ces modifications sur l\ Amérique du Sud, une carotte de glace 137 metreslong a été récupéré de la Cordillere des Andes, dans le Bassin Amazonien Occidental, au sommet du Nevado
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 17/10/2003
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3. Comparisons of Protocols for Decontamination of Environmental Ice Samples for Biological and Molecular Examinations
Drilling and laboratory manipulations of glacial ice cores introduce contemporary microbes and biomolecules onto the cores. We report herein a systematic comparative study of several decontamination protocols. Only treatment with 5% sodium hypochlorite eliminated all external contaminating microbes and nucleic acids while maintaining the integrity of those w
American Society for Microbiology.
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4. Gases in ice cores
Air trapped in glacial ice offers a means of reconstructing variations in the concentrations of atmospheric gases over time scales ranging from anthropogenic (last 200 yr) to glacial/interglacial (hundreds of thousands of years). In this paper, we review the glaciological processes by which air is trapped in the ice and discuss processes that fractionat
The National Academy of Sciences of the USA.
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5. Diversity and association of psychrophilic bacteria in Antarctic sea ice.
The bacterial populations associated with sea ice sampled from Antarctic coastal areas were investigated by use of a phenotypic approach and a phylogenetic approach based on genes encoding 16S rRNA (16S rDNA). The diversity of bacteria associated with sea ice was also compared with the bacterial diversity of seawater underlying sea ice. Psychrophilic (optima
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6. Diversity of Holocene life forms in fossil glacier ice
Studies of biotic remains of polar ice caps have been limited to morphological identification of plant pollen and spores. By using sensitive molecular techniques, we now demonstrate a much greater range of detectable organisms; from 2000- and 4000-year-old ice-core samples, we obtained and characterized 120 clones that represent at least 57 distinct taxa and
The National Academy of Sciences.
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7. Proteins in frozen solutions: evidence of ice-induced partial unfolding.
From a drastic decrease in the phosphorescence lifetime of tryptophan residues buried in compact rigid cores of globular proteins, it was possible to demonstrate that freezing of aqueous solutions is invariably accompanied by a marked loosening of the native fold, an alteration that entails considerable loss of secondary and tertiary structure. The phenomeno
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8. A habitat for psychrophiles in deep Antarctic ice
Microbes, some of which may be viable, have been found in ice cores drilled at Vostok Station at depths down to ≈3,600 m, close to the surface of the huge subglacial Lake Vostok. Two types of ice have been found. The upper 3,500 m comprises glacial ice containing traces of nutrients of aeolian origin including sulfuric acid, nitric acid, methanosulfon
The National Academy of Sciences.
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9. Sea Ice Microbial Communities: Distribution, Abundance, and Diversity of Ice Bacteria in McMurdo Sound, Antarctica, in 1980
An abundant and diverse bacterial community was found within brine channels of annual sea ice and at the ice-seawater interface in McMurdo Sound, Antarctica, in 1980. The mean bacterial standing crop was 1.4 × 1011 cells m−2 (9.8 mg of C m−2); bacterial concentrations as high as 1.02 × 1012 cells m−3 were observed in ice core melt water. Vertical pro
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10. Phylogenetic Analysis of Anaerobic Psychrophilic Enrichment Cultures Obtained from a Greenland Glacier Ice Core
The examination of microorganisms in glacial ice cores allows the phylogenetic relationships of organisms frozen for thousands of years to be compared with those of current isolates. We developed a method for aseptically sampling a sediment-containing portion of a Greenland ice core that had remained at −9°C for over 100,000 years. Epifluorescence microsc
American Society for Microbiology.
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11. Bacterial Activity at −2 to −20°C in Arctic Wintertime Sea Ice
Arctic wintertime sea-ice cores, characterized by a temperature gradient of −2 to −20°C, were investigated to better understand constraints on bacterial abundance, activity, and diversity at subzero temperatures. With the fluorescent stains 4′,6′-diamidino-2-phenylindole 2HCl (DAPI) (for DNA) and 5-cyano-2,3-ditoyl tetrazolium chloride (CTC) (for O2
American Society for Microbiology.
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12. Utilization of Fluorescent Microspheres and a Green Fluorescent Protein-Marked Strain for Assessment of Microbiological Contamination of Permafrost and Ground Ice Core Samples from the Canadian High Arctic
Fluorescent microspheres were applied in a novel fashion during subsurface drilling of permafrost and ground ice in the Canadian High Arctic to monitor the exogenous microbiological contamination of core samples obtained during the drilling process. Prior to each drill run, a concentrated fluorescent microsphere (0.5-μm diameter) solution was applied to the
American Society for Microbiology.