Rapid solubility and mineral storage of CO2 in basalt

The long-term security of geologic carbon storage is critical to its success and public acceptance. Much of the security risk associated with geological carbon storage stems from its buoyancy. Gaseous and supercritical CO2 are less dense than formation waters, providing a driving force for it to escape back to the surface. This buoyancy can be eliminated by the dissolution of CO2 into water prior to, or during its injection into the subsurface. The dissolution makes it possible to inject into fractured rocks and further enhance mineral storage of CO2 especially if injected into silicate rocks rich in divalent metal cations such as basalts and ultra-mafic rocks. We have demonstrated the dissolution of CO2 into water during its injection into basalt leading to its geologic solubility storage in less than five minutes and potential geologic mineral storage within few years after injection [1–3]. The storage potential of CO2 within basaltic rocks is enormous. All the carbon released from burning of all fossil fuel on Earth, 5000 GtC, can theoretically be stored in basaltic rocks [4]

Upper limit on the axion-photon coupling from magnetic white dwarf polarization

Polarization measurements of thermal radiation from magnetic white dwarf (MWD) stars have been proposed as a probe of axion-photon mixing. The radiation leaving the surface of the MWD is unpolarized, but if low-mass axions exist then photons polarized parallel to the direction of the MWD's magnetic field may convert into axions, which induces a linear polarization dependent on the strength of the axion-photon coupling gaγγ. We model this process by using the formalism of axion-photon mixing in the presence of strong-field vacuum birefringence to show that of all stellar types MWDs are the most promising targets for axion-induced polarization searches. We then consider linear polarization data from multiple MWDs, including SDSS J135141 and Grw+70°8247, to show that after rigorously accounting for astrophysical uncertainties the axion-photon coupling is constrained to |gaγγ|≲5.4×10-12 GeV-1 at 95% confidence for axion masses ma≲3×10-7 eV. This upper limit puts in tension the previously-suggested explanation of the anomalous transparency of the Universe to TeV gamma-rays in terms of axions. We identify MWD targets for which future data and modeling efforts could further improve the sensitivity to axions

L'intérêt des races mixtes dans les systèmes laitiers : enseignements du projet BlueSel

La « Bleue Mixte » (BM) est une race à petit effectif localisée de part et d’autre de la frontière franco-belge. Menacée de disparition, elle bénéficie d’un projet transfrontalier BlueSel soutenu par le programme européen INTERREG IV et les autorités françaises et wallonnes. L’objectif de ce projet est d’assurer la conservation, la sélection et la promotion de la BM. L’un des volets du programme a consisté à étudier la rentabilité économique des troupeaux BM. Il s’est appuyé sur un réseau de 16 fermes de références mis en place fin 2008 jusque mi 2012. La collecte des données techniques et économiques sur les 4 années comptables de 2007 à 2010 a reposé sur la méthodologie mise en oeuvre au sein du dispositif français des Réseaux d’élevage. Les exploitations BM ont été regroupées selon deux systèmes, herbivore et polyculture-élevage, et comparées aux exploitations laitières Prim’Holstein (PH) du Réseau d’élevage de Nord-Picardie. Les résultats démontrent la capacité des éleveurs de vaches BM à obtenir de bonnes performances économiques malgré de plus faibles productivité laitière (4225 l/VL) et taux (3,70 % de MG et 3,22 % de protéines), et un moindre prix du lait, grâce notamment à une conduite de troupeaux bien maîtrisée, des surfaces fourragères très bien valorisées, et la mixité lait-viande très affirmée de la race qui atténue les fluctuations du prix du lait. En système herbivore, les exploitations BM s’avèrent économes et autonomes avec une excellente valorisation des prairies. En système de polyculture-élevage, les troupeaux sont conduits de façon à peine plus intensive qu’en système herbivore, contrairement aux troupeaux PH.BlueSe

A multi-decadal view of the heat and mass budget of a volcano in unrest: La Soufrière de Guadeloupe (French West Indies)

Particularly in the presence of a hydrothermal system, many volcanoes output large quantities of heat through the transport of water from deep within the edifice to the surface. Thus, heat flux is a prime tool for evaluating volcanic activity and unrest. We review the volcanic unrest at La Soufrière de Guadeloupe (French West Indies) using an airborne thermal camera survey and in situ measurements of temperature and flow rate through temperature probes, Pitot-tube and MultiGAS measurements. We deduce mass and heat fluxes for the fumarolic, ground and thermal spring outputs and follow these over a period spanning 2000–2020. Our results are compared with published data and we performed a retrospective analysis of the temporal variations in heat flux over this period using the literature data. We find that the heat emitted by the volcano is 36.5 ± 7.9MW, of which the fumarolic heat flux is dominant at 28.3 ± 6.8 MW. Given a total heated area of 26 270 m2, this equates to a total heat flux density of 1366 ± 82 W/m2, which is amongst the highest established for worldwide volcanoes with hydrothermal systems, particularly for dome volcanoes. A major change at La Soufrière de Guadeloupe, however, is the development of a widespread region of ground heating at the summit where heat output has increased from 0.2 ± 1 MW in 2010 to 5.7 ± 0.9 MW in 2020. This change is concurrent with accelerating unrest at the volcano and the emergence of two new high-flux fumaroles in recent years. Our findings highlight the importance of continued and enhanced surveillance and research strategies at La Soufrière de Guadeloupe, the results of which can be used to better understand hydrothermal volcanic systems the world over