Abstract: What are the long-term consequences of invasive species? After invasion, how long do ecosystems require to reach a new equilibrium? Answering these questions requires long-term, high-resolution data that are vanishingly rare. We combined the analysis of environmental DNA extracted from a lake sediment core, coprophilous fungi, and sedimentological analyses to reconstruct 600 years of ecosystem dynamics on a sub-Antarctic island and to identify the impact of invasive rabbits. Plant communities remained stable from AD 1400 until the 1940s, when the DNA of invasive rabbits was detected in sediments. Rabbit detection corresponded to abrupt changes of plant communities, with a continuous decline of a dominant plant species. Furthermore, erosion rate abruptly increased with rabbit abundance. Rabbit impacts were very fast and were stronger than the effects of climate change during the 20th century. Lake sediments can allow an integrated temporal analysis of ecosystems, revealing the impact of invasive species over time and improving our understanding of underlying mechanisms. Rabbits have had a stronger impact on the landscape and plant communities of a remote island than one century of climate change. Rabbits have had a stronger impact on the landscape and plant communities of a remote island than one century of climate change.

Abstract: Geochemical investigations using FTIR, ICP-AES and C-N analyses were carried out on a single-family semi-subterranean Inuit house in order to assess the contribution of Inuit domestic activities in the formation of cryosolic soils in a periglacial archaeological context (Kuuvik Bay, Nunavik, Canada). The geochemical elements data were analyzed using box plots and enrichment factors. The information was also summarized and visualized through principal component analysis (PCA). These complementary statistical approaches provided evidence of a moderate but identifiable and significant imprint of Inuit domestic activities on soil geochemistry. The box plots indicate moderate Ca, Mn, Cu and P enrichments and more noticeable Mg, Fe and S enrichments. These enrichment factors and the ICP-AES data show that samples from the peripheral wall and the tunnel entrance of the house and its vicinity are significantly enriched. While FTIR analysis highlighted the main soil element contents (e.g., organic and mineral components), ICP-AES analysis was used to further document variations in the background elements throughout the site. However, the obtained results do not allow us to undertake a spatial analysis of Inuit activities or to describe them in detail. In addition, the data highlight the difficulty of documenting the natural variability of element contents in cryosolic soils, especially in archaeological contexts. Cryo-pedological processes in the active layer as well as house cleaning and nutrient inputs resulting from Inuit occupations may have attenuated chemical signatures of previous Inuit domestic activities.

Abstract: This paper analyses atmospheric ionizing radiations induced by Galactic and Solar Cosmic Rays (GCR and SCR, respectively) thanks to continuous measurements of neutron spectrum operated in high-altitude stations. Analyses are reinforced using GCR and SCR models, and extensive air shower descriptions
based on nuclear transport simulations. First analyses were focused on neutron fluxes as function of altitude. Secondly, atmospheric ionizing radiation impacts on biological doses during quiet period and extreme solar events are presented. On the basis of the relevant comparisons conducted for ambient dose equivalent
during quiet solar activity, but also for the comic ray variations calculated and recorded on neutron monitor (NM) during Ground Level Enhancement (GLE) event. GLE 5 model was applied to London ↔ New-york flight dose calculations. All of these results show that dose values vary drastically, on the one hand with the route path (latitude, longitude altitude), on the other hand with the phasing of the solar event. Specific case of Antarctica is discussed because it combines both the high altitude and the very low magnetic field. Analyses show that ionizing radiation in Antarctica environment can be a problematic from the point of view of the human dose, which exerts classical recommendations established for public. This highlights the importance of monitoring atmospheric ionizing radiation, more particularly extreme solar events, then to develop semi-empirical and particle transport method for reliable calculation of dose levels.