59 resultados para Lesson Identified
em Publishing Network for Geoscientific
Resumo:
Microorganisms play an important role in the transformation of material within the earth's crust. The storage of CO2 could affect the composition of inorganic and organic components in the reservoir, consequently influencing microbial activities. To study the microbial induced processes together with geochemical, petrophysical and mineralogical changes, occurring during CO2 storage, long-term laboratory experiments under simulated reservoir P-T conditions were carried out. Clean inner core sections, obtained from the reservoir region at the CO2 storage site in Ketzin (Germany) from a depth of about 650 m, were incubated in high pressure vessels together with sterile synthetic formation brine under in situ P-T conditions of 5.5 MPa and 40°C. A 16S rDNA based fingerprinting method was used to identify the dominant species in DNA extracts of pristine sandstone samples. Members of the alpha- and beta-subdivisions of Proteobacteria and the Actinobacteria were identified. So far sequences belonging to facultative anaerobic, chemoheterotrophic bacteria (Burkholderia fungorum, Agrobacterium tumefaciens) gaining their energy from the oxidation of organic molecules and a genus also capable of chemolithoautotrophic growth (Hydrogenophaga) was identified. During CO2 incubation minor changes in the microbial community composition were observed. The majority of microbes were able to adapt to the changed conditions. During CO2 exposure increased concentrations of Ca**2+, K**+, Mg**2+ and SO4**2- were observed. Partially, concentration rises are (i) due to equilibration between rock pore water and synthetic brine, and (ii) between rock and brine, and are thus independent on CO2 exposure. However, observed concentrations of Ca**2+, K**+, Mg**2+ are even higher than in the original reservoir fluid and therefore indicate mineral dissolution due to CO2 exposure.
Resumo:
An interdisciplinary study was conducted at Qijurittuq (IbGk-3), an archaeological site located on Drayton Island along the eastern shore of Hudson Bay, Nunavik. Local Inuit made important contributions to the research. High school students participated in the field school, and elders shared their traditional knowledge. The elders expressed an interest in the source of the wood used to construct Qijurittuq's semi-subterranean dwellings, and this inspired us to expand our research in that direction. This interdisciplinary study included a reconstruction of the geomorphological and environmental history of Drayton Island, wood provenance and dendrochronology studies, research on house architecture and settlement patterns, and a zooarchaeological analysis. This paper synthesizes the preliminary results of this interdisciplinary investigation within the context of climate change. We discuss the persistence of semi-subterranean dwellings in eastern Hudson Bay long after they had been abandoned elsewhere. At Qijurittuq, their abandonment corresponds with the end of Little Ice Age. However, at the same time, the development of more permanent contact with Euro-Canadians was having a strong impact upon Inuit culture.
Resumo:
Ocean Drilling Program Leg 169S retrieved a complete Holocene sequence from Saanich Inlet, British Columbia, Canada. Fish and diatom remains were extracted from sediments at Site 1034. Very small fish bones, teeth and scales were ubiquitous except in the lowermost glaciomarine clays; scales degraded with depth. In the identifiable fraction, Pacific herring were the most abundant with Pacific hake and cartilaginous fish yielding significant fractions. Fish remains appear just before 12 000 BP but greatest diversity does not occur until about 6500 BP. A smoothed abundance curve highlights two periods of maximal abundance at about 1500 and 6500 BP. Abundances in the last 1000 years are lower than the rest of the record. A correlation with abundances of seven phytoplankton taxa is significant; diatoms explain about a third of the variance. This study demonstrates the use of fish and diatoms from the same paleosedimentary matrix to examine millennia-scale correlations between primary and tertiary production.
Resumo:
Intraspecific differences in the diets of many species of pinnipeds are to be expected in view of the great differences in morphology, life history and foraging behaviour between the sexes of many species. We examined the diet of the Antarctic fur seal population at Bouvetøya, Southern Ocean, to assess intersexual differences. This was made possible by the analysis of prey remains extracted from scats and regurgitations collected in areas used primarily by one or the other sex. The results indicate that both males and females feed primarily on Antarctic krill Euphausia superba with several species of fish and squid being taken, likely opportunistically given their prevalence. Significant differences were identified in the frequency of occurrence of otoliths in scats and the percentage numerical abundance of the major fish prey species in the diet. Adult males ate a smaller quantity of fish overall, but ate significantly more of the larger fish species. The greater diving capabilities of males and the fact that they are not limited in the extent of their foraging area by having to return regularly to feed dependant offspring may play a role in the differences found between the diets of males and females. Additionally, females might be more selective, favouring myctophids because they are richer in energy than krill. The absence of major differences in the diet between the sexes at this location is likely due to the high overall abundance of prey at Bouvetøya.