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Chuxian Li, Jeroen E. Sonke, Gaël Le Roux, Natalia Piotrowska, Nathalie Van der Putten, Stephen J. Roberts, Tim Daley, Emma Rice, Roland Gehrels, Maxime Enrico, Dmitri Mauquoy, Thomas P. Roland, François De Vleeschouwer. (2020). Unequal Anthropogenic Enrichment of Mercury in Earth’s Northern and Southern Hemispheres (Vol. 4). Bachelor's thesis, , .
Abstract: Remote Northern Hemisphere (NH) and Southern Hemisphere (SH) lake sediment and peat records of mercury (Hg) deposition have shown a ×3 to ×5 Hg enrichment since pre-industrial times (<1880 AD), leading to the perception that global atmospheric Hg enrichment is moderate and uniform across the hemispheres. Anthropogenic Hg emissions in the NH are, however, approximately 4 times higher than those in the SH. Here, we reconstruct atmospheric Hg deposition in four remote SH peatlands and review sediment and peat Hg records from both hemispheres. We observe a ×4 all-time enrichment in SH Hg deposition from pre-anthropogenic (<1450 AD) to the late 20th-century periods, which is lower than the large ×16 all-time enrichment in NH Hg deposition. We attribute this difference to lower anthropogenic Hg emissions in the SH, and higher natural atmospheric SH Hg concentrations, supported by ×2 higher natural background Hg accumulation in SH peat records. We suggest that the higher SH natural atmospheric Hg deposition reflects the SH land–ocean distribution, and is driven by important SH marine Hg emissions. Our findings indicate that atmospheric Hg background levels and anthropogenic enrichment in both hemispheres are different and should be taken into account in international Hg assessments and environmental policy.
Programme: 1065,1133
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Minier, Vincent; Durand, Gilles; Lagage, Pierre-Olivier; Talvard, M. (2007). CAMISTIC: THz/submm astronomy at Dome C in Antarctica (Vol. 14).
Abstract: Abstract Submillimetre (submm) astronomy is the prime technique to unveil the birth and early evolution of a broad range of astrophysical objects. It is a relatively new branch of observational astrophysics which focuses on studies of the cold Universe, i.e., objects radiating a significant if not dominant fraction of their energy at wavelengths ranging from ˜ 100 μm to ˜ 1 mm. Submm continuum observations are particularly powerful to measure the luminosities, temperatures and masses of cold dust emitting objects. Examples of such objects include star-forming clouds in our Galaxy, prestellar cores and deeply embedded protostars, protoplanetary disks around young stars, as well as nearby starburst galaxies and dust-enshrouded high-redshift galaxies in the early Universe.
Programme: 1040
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Bulat S., Alekhina I A Blot M., Petit J.R., De Angelis M., Wagenbach D. Lipenkov V.Y.,. (2004). DNA signature of thermophilic bacteria from the aged accretion ice of Lake Vostok, Antarctica: implications for searching for life in extreme icy environments. International journal of astrobiology, 3(1), 1–12.
Abstract: We have used 16S ribosomal genes to estimate the bacterial contents of Lake Vostok accretion ice samples at 3551 m and 3607 m, both containing sediment inclusions and formed 20000–15000 yr ago. Decontamination proved to be a critical issue, and we used stringent ice chemistry-based procedures and comprehensive biological controls in order to restrain contamination. As a result, up to now we have only recognized one 16S rDNA bacterial phylotype with confident relevance to the lake environment. It was found in one sample at 3607 m depth and represents the extant thermophilic facultative chemolithoautotroph Hydrogenophilus thermoluteolus of beta-Proteobacteria, and until now had only been found in hot springs. No confident findings were detected in the sample at 3551 m, and all other phylotypes revealed (a total of 16 phylotypes, 336 clones including controls) are presumed to be contaminants. It seems that the Lake Vostok accretion ice is actually microbe-free, indicating that the water body should also be hosting a highly sparse life. The message of thermophilic bacteria suggests that a geothermal system exists beneath the cold water body of Lake Vostok, what is supported by the geological setting, the long-term seismotectonic evidence from 4He degassing and the ‘18O shift’ of the Vostok accretion ice. The seismotectonic activity that seems to operate in deep faults beneath the lake could sustain thermophilic chemolithoautotrophic microbial communities. Such a primary production scenario for Lake Vostok may have relevance for icy planets and the approaches used for estimating microbial contents in accretion ice are clearly relevant for searching for extraterrestrial life.
Programme: 355
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E. Dobrica, R. C. Ogliore, C. Engrand, K. Nagashima, A. J. Brearley. (2018). Origins of Secondary Minerals in Micrometeorites (Vol. 24). Bachelor's thesis, , .
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Henri Weimerskirch, Fabrice Le Bouard, Peter G. Ryan, C. A. Bost. (2018). Massive decline of the world’s largest king penguin colony at Ile aux Cochons, Crozet (Vol. 30). Bachelor's thesis, , .
Abstract: King penguins (Aptenodytes patagonicus Miller) are major consumers in the Southern Ocean. The colony at Ile aux Cochons, Iles Crozet, in the southern Indian Ocean was known in the 1980s as the largest king penguin colony and the second largest penguin colony in the world. However, there have not been any recent estimates of this colony. Aerial photographs taken from a helicopter, and satellite images were used to report on changes in the colony and population sizes over the past 50 years. The colony has declined by 88% over the past 35 years, from c. 500 000 pairs to 60 000 pairs. The possible causes of this decline were explored but no plausible explanation for such an unprecedented decrease in penguin populations was found. The study highlights the use of satellite imagery as a non-invasive technique for population monitoring, and stresses the need for further research on the causes of this alarming trend in this colony.
Keywords: Aptenodytes patagonicus remote sensing satellite image
Programme: 109,394
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Ricaud P, Carminati F, Courcoux Y, Pellegrini A, Attié J-L, El Amraoui L, Abida R, Genthon C, August T, Warner J, . (2014). Statistical analyses and correlation between tropospheric temperature and humidity at Dome C, Antarctica
. Antarct. Sci., 26(03), 290–308.
Abstract: The Dome C (Concordia) station in Antarctica (75°06'S, 123°21'E, 3233 m amsl) has a unique opportunity to test the quality of remote-sensing measurements and meteorological analyses because it is situated well inside the Eastern Antarctic Plateau and is less affected by local phenomena. Measurements of tropospheric temperature and water vapor (H2O) together with the integrated water vapor (IWV) performed in 2010 are statistically analyzed to assess their quality and to study the yearly correlation between temperature and H2O over the entire troposphere. The statistical tools include yearly evolution, seasonally-averaged mean and bias, standard deviation and linear Pearson correlation. The datasets are made of measurements from the ground-based microwave radiometer H2O Antarctica Microwave Stratospheric and Tropospheric Radiometer (HAMSTRAD), radiosonde, in-situ sensors, the space-borne infrared sensors Infrared Atmospheric Sounding Interferometer (IASI) on the MetOp-A platform and the Atmospheric InfraRed Sounder (AIRS) on the AQUA platform, and the analyses from the European Centre for Medium-Range Weather Forecast (ECMWF). Despite some obvious biases within all these datasets, our study shows that temperature and IWV are generally measured with high quality whilst H2O measurement quality is slightly worse. The AIRS and IASI measurements do not have the vertical resolution to correctly probe the lowermost troposphere, whilst HAMSTRAD loses sensitivity in the upper troposphere-lower stratosphere. Within the entire troposphere over the whole year, it is found that the time evolution of temperature and H2O is highly correlated (> 0.8). This suggests that, in addition to the variability of solar radiation producing in summer an obvious diurnal cycle in the planetary boundary layer and an obvious seasonal cycle over the year, the H2O and temperature intra-seasonal variabilities are affected by the same processes, e.g. related to the long-range transport of air masses.
Keywords: ground-based sensors,, , integrated water vapour, meteorological analyses, radiosonde, space-borne sensors,
Programme: 910,1013
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Thiebot Jean-Baptiste, Lescroël Amélie, Barbraud Christophe, Bost Charles-André, . (2013). Three-dimensional use of marine habitats by juvenile emperor penguins Aptenodytes forsteri during post-natal dispersal
. Antarct. Sci., 25(04), 536–544.
Abstract: The juvenile phase is poorly known in Antarctic seabirds, despite being a critical period for individual survival. To better understand the ecology of young Antarctic seabirds, we surveyed for the first time the three-dimensional habitat use of six juvenile emperor penguins during their post-natal dispersal from Terre Adélie, using bio-telemetric tags. The tags transmitted location and activity data for nearly 100 days on average. One individual was followed during eight months and covered 7000 km, which represents the longest continuous individual survey for the species. Studied individuals first dispersed away from Antarctica, up to 54.7°S and 1250 km north of the pack-ice edge, in the Polar Frontal Zone. This highlighted a much looser association with sea ice and a greater at-sea range compared to previous knowledge on breeding adults. Juvenile penguins then moved southwards close to the extending pack-ice during autumn and winter. Over the survey duration, juveniles showed a contrasting use of marine habitats, with less mobility, less time underwater, and shallower dives (generally not over 50–100 m) in the pack ice, versus greater distances travelled, more time spent underwater, especially deeper than 100 m (up to 250–300 m) in open water. We discuss hypotheses which could explain the northward exodus of juvenile emperor penguins across contrasting habitats.
Keywords: Diving, foraging ecology, immaturity period, migration, seabirds, Southern Ocean, tracking,
Programme: 109,394
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Renault D., Lalouette L. (2012). Short Note: Critical thermal minima of three sub-Antarctic insects from the French southern Indian Ocean islands
. Antarctic Science, 24(01), 43–44.
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Barbraud Christophe, Gavrilo Maria, Mizin Yuri, Weimerskirch Henri, . (2011). Comparison of emperor penguin declines between Pointe Géologie and Haswell Island over the past 50 years
. 0954-1020, 23(05), 461–468.
Keywords: Antarctica, Aptenodytes forsteri, climate change, population trends, sea ice extent,
Programme: 109
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Thiebot Jean-Baptiste, Lescroël Amélie, Pinaud David, Trathan Philip N, Bost Charles-André, . (2011). Larger foraging range but similar habitat selection in non-breeding versus breeding sub-Antarctic penguins
. Antarct. Sci., 23(02), 117–126.
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