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Author Yan Axel Gómez Coutouly doi  openurl
  Title Questioning the Anthropic Nature of Pedra Furada and the Piauí Sites Type Journal
  Year (down) 2022 Publication PaleoAmerica Abbreviated Journal  
  Volume 8 Issue 1 Pages 29-52  
  Keywords Brazil geofacts Late Glacial Maximum Pedra Furada Peopling of the Americas  
  Abstract Many archaeologists are still skeptical about a human presence in the Americas during or before the Late Glacial Maximum (LGM), considering that the claim is not yet sustained by hard evidence. Boqueirão da Pedra Furada (Brazil) is one of the most famous pre-LGM claims, but the site has so far been considered ambiguous, and similar concerns have been raised about nearby sites. Nonetheless, for E. Boëda and co-workers, who have been working at these sites, researchers who are still skeptical about the anthropic origin of the assemblages have a psychological barrier and no scientific arguments. Are all skeptics completely blinded by their preconceptions that they cannot see the obvious and unambiguous evidence? To find out, I reviewed the numerous publications of the Piauí sites, and the outcome of my analysis is quite simple: the anthropic nature of the LGM/pre-LGM artifacts of the Piauí sites has not been demonstrated.  
  Programme 1217  
  Campaign  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2055-5563 ISBN Medium  
  Area Expedition Conference  
  Notes Approved yes  
  Call Number Serial 8585  
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Author Stuart Russell, Jessica C. E. Irving, Sanne Cottaar doi  openurl
  Title Seismic visibility of melt at the core-mantle boundary from PKKP diffracted waves Type Journal
  Year (down) 2022 Publication Earth and Planetary Science Letters Abbreviated Journal  
  Volume 595 Issue Pages 117768  
  Keywords core-mantle boundary lower mantle melt PKKP diffracted seismic visibility  
  Abstract The core-mantle boundary (CMB) is a complex and poorly understood region of the Earth. The existence of melt or partial melt at the CMB is strongly debated with evidence coming from a range of sources. While partial melt has been inferred in specific locations using seismology, often as an explanation for ultra-low velocity zones (ULVZs), no global layer of melt has been observed despite evidence that such melt should accumulate at the CMB. Using high frequency synthetic seismograms we have systematically examined the effect of a one-dimensional melt layer at the CMB on the global seismic wavefield. We find that PKKP diffracted waves are an extremely sensitive, robust and previously underutilised seismic phase for studying the CMB and, in synthetic testing, could resolve very thin melt layers. We have constructed a global data set of PKKP diffracted observations to attempt to observe or exclude melt at the CMB. We find that within the bounds of our data, we are unable to robustly exclude or observe a melt layer at the CMB on the order of single kilometres thick. The presence of a thin layer of unobservable melt at the CMB would have profound impacts for the internal dynamics of the Earth.  
  Programme 133  
  Campaign  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0012-821X ISBN Medium  
  Area Expedition Conference  
  Notes Approved yes  
  Call Number Serial 8586  
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Author Nicolas Cortiade, Adélie Delacour, Damien Guillaume, Bertrand Moine, June Chevet doi  openurl
  Title Serpentinization of mantle xenoliths in Kerguelen archipelago: A first petrographic and geochemical study Type Journal
  Year (down) 2022 Publication Lithos Abbreviated Journal  
  Volume 428-429 Issue Pages 106796  
  Keywords Fluid composition Fluid origin Kerguelen Mantle xenoliths Serpentinization  
  Abstract The spinel harzburgites xenoliths from the Lac Michèle outcrop, Kerguelen archipelago (South Indian Ocean), have the particularity to show unique and unusual evidences of fluids circulation and especially of serpentinization. In this paper, in situ and whole-rock petrographic and geochemical data on a selection of variously serpentinized samples are presented and attest that several episodes of fluid-rock interaction occurred. Serpentinization processes affected notably and with variable degrees the spinel harzburgites leading to changes in their mineralogy and chemical compositions. Degree of serpentinization ranges from very slight (LOI < 3 wt% and Fe3+/Fetot < 0.1) to moderate (4 wt% < LOI < 6 wt% and 0.21 < Fe3+/Fetot < 0.33). Most serpentinized samples show a preferential petrographic direction of serpentinization, forming a subparallel serpentine network, which is sometimes intersected by serpentine veins. As a result, at least two serpentinization episodes were identified within the Lac Michèle samples, without any chemical differences between the two generations except for Cl content. This suggests very few chemical evolution of the system during serpentinization. Due to the significant amount of Cl measured in serpentine minerals (601 ppm on average), the nature of the fluids that interacted with the spinel harzburgites xenoliths during the serpentinization events can be hypothesized to be seawater-like or seawater-derived fluids.  
  Programme 1077  
  Campaign  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0024-4937 ISBN Medium  
  Area Expedition Conference  
  Notes Approved yes  
  Call Number Serial 8587  
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Author Georg Lackner, Florent Domine, Daniel F. Nadeau, Matthieu Lafaysse, Marie Dumont doi  openurl
  Title Snow properties at the forest–tundra ecotone: predominance of water vapor fluxes even in deep, moderately cold snowpacks Type Journal
  Year (down) 2022 Publication The Cryosphere Abbreviated Journal  
  Volume 16 Issue 8 Pages 3357-3373  
  Keywords  
  Abstract The forest–tundra ecotone is a large circumpolar transition zone between the Arctic tundra and the boreal forest, where snow properties are spatially variable due to changing vegetation. The extent of this biome through all circumpolar regions influences the climate. In the forest–tundra ecotone near Umiujaq in northeastern Canada (56∘33′31′′ N, 76∘28′56′′ W), we contrast the snow properties between two sites, TUNDRA (located in a low-shrub tundra) and FOREST (located in a boreal forest), situated less than 1 km apart. Furthermore, we evaluate the capability of the snow model Crocus, initially developed for alpine snow, to simulate the snow in this subarctic setting. Snow height and density differed considerably between the two sites. At FOREST, snow was about twice as deep as at TUNDRA. The density of snow at FOREST decreased slightly from the ground to the snow surface in a pattern that is somewhat similar to alpine snow. The opposite was observed at TUNDRA, where the pattern of snow density was typical of the Arctic. We demonstrate that upward water vapor transport is the dominant mechanism that shapes the density profile at TUNDRA, while a contribution of compaction due to overburden becomes visible at FOREST. Crocus was not able to reproduce the density profiles at either site using its standard configuration. We therefore implemented some modifications for the density of fresh snow, the effect of vegetation on compaction, and the lateral transport of snow by wind. These adjustments partly compensate for the lack of water vapor transport in the model but may not be applicable at other sites. Furthermore, the challenges using Crocus suggest that the general lack of water vapor transport in the snow routines used in climate models leads to an inadequate representation of the density profiles of even deep and moderately cold snowpacks, with possible major impacts on meteorological forecasts and climate projections.  
  Programme 1042  
  Campaign  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1994-0416 ISBN Medium  
  Area Expedition Conference  
  Notes Approved yes  
  Call Number Serial 8588  
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Author Sophia Ferchiou, France Caza, Richard Villemur, Stéphane Betoulle, Yves St-Pierre doi  openurl
  Title Species- and site-specific circulating bacterial DNA in Subantarctic sentinel mussels Aulacomya atra and Mytilus platensis Type Journal
  Year (down) 2022 Publication Scientific Reports Abbreviated Journal  
  Volume 12 Issue 1 Pages 9547  
  Keywords Ecology Microbial ecology  
  Abstract Impacts of climate changes are particularly severe in polar regions where warmer temperatures and reductions in sea-ice covers threaten the ecological integrity of marine coastal ecosystems. Because of their wide distribution and their ecological importance, mussels are currently used as sentinel organisms in monitoring programs of coastal ecosystems around the world. In the present study, we exploited the concept of liquid biopsy combined to a logistically friendly sampling method to study the hemolymphatic bacterial microbiome in two mussel species (Aulacomya atra and Mytilus platensis) in Kerguelen Islands, a remote Subantarctic volcanic archipelago. We found that the circulating microbiome signatures of both species differ significantly even though their share the same mussel beds. We also found that the microbiome differs significantly between sampling sites, often correlating with the particularity of the ecosystem. Predictive models also revealed that both species have distinct functional microbiota, and that the circulating microbiome of Aulacomya atra was more sensitive to changes induced by acute thermal stress when compared to Mytilus platensis. Taken together, our study suggests that defining circulating microbiome is a useful tool to assess the health status of marine ecosystems and to better understand the interactions between the sentinel species and their habitat.  
  Programme 1044  
  Campaign  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2045-2322 ISBN Medium  
  Area Expedition Conference  
  Notes Approved yes  
  Call Number Serial 8589  
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Author Aymeric Fromant, John P. Y. Arnould, Karine Delord, Grace J. Sutton, Alice Carravieri, Paco Bustamante, Colin M. Miskelly, Akiko Kato, Maud Brault-Favrou, Yves Cherel, Charles-André Bost file  doi
openurl 
  Title Stage-dependent niche segregation: insights from a multi-dimensional approach of two sympatric sibling seabirds Type Journal
  Year (down) 2022 Publication Oecologia Abbreviated Journal  
  Volume 199 Issue 3 Pages 537-548  
  Keywords Diving petrel Foraging and diving behaviour Niche partitioning Pelecanoides Trophic niche  
  Abstract Niche theory predicts that to reduce competition for the same resource, sympatric ecologically similar species should exploit divergent niches and segregate in one or more dimensions. Seasonal variations in environmental conditions and energy requirements can influence the mechanisms and the degree of niche segregation. However, studies have overlooked the multi-dimensional aspect of niche segregation over the whole annual cycle, and key facets of species co-existence still remain ambiguous. The present study provides insights into the niche use and partitioning of two morphologically and ecologically similar seabirds, the common (CDP, Pelecanoides urinatrix) and the South Georgian diving petrel (SGDP, Pelecanoides georgicus). Using phenology, at-sea distribution, diving behavior and isotopic data (during the incubation, chick-rearing and non-breeding periods), we show that the degree of partitioning was highly stage-dependent. During the breeding season, the greater niche segregation during chick-rearing than incubation supported the hypothesis that resource partitioning increases during energetically demanding periods. During the post breeding period, while species-specific latitudinal differences were expected (species specific water mass preference), CDP and SGDP also migrated in divergent directions. This segregation in migration area may not be only a response to the selective pressure arising from competition avoidance between sympatric species, but instead, could reflect past evolutionary divergence. Such stage-dependent and context-dependent niche segregation demonstrates the importance of integrative approaches combining techniques from different fields, throughout the entire annual cycle, to better understand the co-existence of ecologically similar species. This is particularly relevant in order to fully understand the short and long-term effects of ongoing environmental changes on species distributions and communities.  
  Programme 109,394  
  Campaign  
  Address  
  Corporate Author Thesis Bachelor's thesis  
  Publisher Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1432-1939 ISBN Medium  
  Area Expedition Conference  
  Notes Approved yes  
  Call Number Serial 8590  
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Author Albane Barbero, Roberto Grilli, Markus M. Frey, Camille Blouzon, Detlev Helmig, Nicolas Caillon, Joël Savarino doi  openurl
  Title Summer variability of the atmospheric NO2 :  NO ratio at Dome C on the East Antarctic Plateau Type Journal
  Year (down) 2022 Publication Atmospheric Chemistry and Physics Abbreviated Journal  
  Volume 22 Issue 18 Pages 12025-12054  
  Keywords  
  Abstract Previous Antarctic summer campaigns have shown unexpectedly high levels of oxidants in the lower atmosphere of the continental plateau and at coastal regions, with atmospheric hydroxyl radical (OH) concentrations up to 4 × 106 cm−3. Such high reactivity in the summer Antarctic boundary layer results in part from the emissions of nitrogen oxides (NOx ≡ NO + NO2) produced during photo-denitrification of the snowpack, but its underlying mechanisms are not yet fully understood, as some of the chemical species involved (NO2, in particular) have not yet been measured directly and accurately. To overcome this crucial lack of information, newly developed optical instruments based on absorption spectroscopy (incoherent broadband cavity-enhanced absorption spectroscopy, IBBCEAS) were deployed for the first time at Dome C (−75.10 lat., 123.33 long., 3233 m a.s.l.) during the 2019–2020 summer campaign to investigate snow–air–radiation interaction. These instruments directly measure NO2 with a detection limit of 30 pptv (parts per trillion by volume or 10−12 mol mol−1) (3σ). We performed two sets of measurements in December 2019 (4 to 9) and January 2020 (16 to 25) to capture the early and late photolytic season, respectively. Late in the season, the daily averaged NO2:NO​​​​​​​ ratio of 0.4 ± 0.4 matches that expected for photochemical equilibrium through Leighton's extended relationship involving ROx (0.6 ± 0.3). In December, however, we observed a daily averaged NO2:NO ratio of 1.3 ± 1.1, which is approximately twice the daily ratio of 0.7 ± 0.4 calculated for the Leighton equilibrium. This suggests that more NO2 is produced from the snowpack early in the photolytic season (4 to 9 December), possibly due to stronger UV irradiance caused by a smaller solar zenith angle near the solstice. Such a high sensitivity of the NO2:NO ratio to the sun's position is of importance for consideration in atmospheric chemistry models.  
  Programme 1177  
  Campaign  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1680-7316 ISBN Medium  
  Area Expedition Conference  
  Notes Approved yes  
  Call Number Serial 8591  
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Author Pete D. Akers, Joël Savarino, Nicolas Caillon, Aymeric P. M. Servettaz, Emmanuel Le Meur, Olivier Magand, Jean Martins, Cécile Agosta, Peter Crockford, Kanon Kobayashi, Shohei Hattori, Mark Curran, Tas van Ommen, Lenneke Jong, Jason L. Roberts doi  openurl
  Title Sunlight-driven nitrate loss records Antarctic surface mass balance Type Journal
  Year (down) 2022 Publication Nature Communications Abbreviated Journal  
  Volume 13 Issue 1 Pages 4274  
  Keywords Cryospheric science Environmental chemistry Palaeoclimate  
  Abstract Standard proxies for reconstructing surface mass balance (SMB) in Antarctic ice cores are often inaccurate or coarsely resolved when applied to more complicated environments away from dome summits. Here, we propose an alternative SMB proxy based on photolytic fractionation of nitrogen isotopes in nitrate observed at 114 sites throughout East Antarctica. Applying this proxy approach to nitrate in a shallow core drilled at a moderate SMB site (Aurora Basin North), we reconstruct 700 years of SMB changes that agree well with changes estimated from ice core density and upstream surface topography. For the under-sampled transition zones between dome summits and the coast, we show that this proxy can provide past and present SMB values that reflect the immediate local environment and are derived independently from existing techniques.  
  Programme 1177  
  Campaign  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2041-1723 ISBN Medium  
  Area Expedition Conference  
  Notes Approved yes  
  Call Number Serial 8592  
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Author Rémi Fay, Sandra Hamel, Martijn van de Pol, Jean-Michel Gaillard, Nigel G. Yoccoz, Paul Acker, Matthieu Authier, Benjamin Larue, Christie Le Coeur, Kaitlin R. Macdonald, Alex Nicol-Harper, Christophe Barbraud, Christophe Bonenfant, Dirk H. Van Vuren, Emmanuelle Cam, Karine Delord, Marlène Gamelon, Maria Moiron, Fanie Pelletier, Jay Rotella, Celine Teplitsky, Marcel E. Visser, Caitlin P. Wells, Nathaniel T. Wheelwright, Stéphanie Jenouvrier, Bernt-Erik Sæther doi  openurl
  Title Temporal correlations among demographic parameters are ubiquitous but highly variable across species Type Journal
  Year (down) 2022 Publication Ecology Letters Abbreviated Journal  
  Volume 25 Issue 7 Pages 1640-1654  
  Keywords capture-recapture demographic correlation demography environmental stochasticity slow-fast continuum stochastic population dynamics temporal covariation  
  Abstract Temporal correlations among demographic parameters can strongly influence population dynamics. Our empirical knowledge, however, is very limited regarding the direction and the magnitude of these correlations and how they vary among demographic parameters and species’ life histories. Here, we use long-term demographic data from 15 bird and mammal species with contrasting pace of life to quantify correlation patterns among five key demographic parameters: juvenile and adult survival, reproductive probability, reproductive success and productivity. Correlations among demographic parameters were ubiquitous, more frequently positive than negative, but strongly differed across species. Correlations did not markedly change along the slow-fast continuum of life histories, suggesting that they were more strongly driven by ecological than evolutionary factors. As positive temporal demographic correlations decrease the mean of the long-run population growth rate, the common practice of ignoring temporal correlations in population models could lead to the underestimation of extinction risks in most species.  
  Programme 109  
  Campaign  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1461-0248 ISBN Medium  
  Area Expedition Conference  
  Notes Approved yes  
  Call Number Serial 8593  
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Author A. Ola, D. Fortier, S. Coulombe, J. Comte, F. Domine doi  openurl
  Title The Distribution of Soil Carbon and Nitrogen Stocks Among Dominant Geomorphological Terrain Units in Qarlikturvik Valley, Bylot Island, Arctic Canada Type Journal
  Year (down) 2022 Publication Journal of Geophysical Research: Biogeosciences Abbreviated Journal  
  Volume 127 Issue 7 Pages e2021JG006750  
  Keywords alluvial fan Arctic permafrost polygon tundra  
  Abstract Soils of circumpolar regions store large amounts of carbon (C) and are a crucial part of the global C cycle. Yet, little is known about the distribution of soil C stocks among geomorphological terrain units of glacial valleys in the Arctic. Soil C and nitrogen (N) content for the top 100 cm of the dominant vegetated geomorphological terrain units (i.e., alluvial fans, humid polygons, mesic polygons) at Qarlikturvik Valley, Bylot Island, Canada have been analyzed. Soil C content was greatest in humid low-center ice-wedge polygons (82 kg m−2), followed by mesic flat-center ice-wedge polygons (40 kg m−2), and alluvial fan area (16 kg m−2), due to prevailing geomorphological processes, differences in vegetation and soil characteristics, as well as permafrost processes. Soil N content was greatest in humid polygons (4 kg m−2), followed by mesic polygons (2 kg m−2), and alluvial fan area (1 kg m−2). Vertically, C and N decreased with increasing depth except for a peak in C at depth in humid polygons, a likely result of past changes in vegetation cover. At Qarlikturvik Valley, which has a size of 121.7 km2, alluvial fans store 0.226 Tg organic C and humid and mesic polygons store 1.643 and 0.218 Tg organic C, respectively in the top 100 cm of soil. Findings like these are important to further constrain pan-Arctic soil C and N stock estimates and thus climate models.  
  Programme 1042  
  Campaign  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2169-8961 ISBN Medium  
  Area Expedition Conference  
  Notes Approved yes  
  Call Number Serial 8594  
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