Deglaciation-enhanced mantle CO2 fluxes at Yellowstone imply positive climate feedback

The generation of mantle melts in response to decompression by glacial unloading has been linked to enhanced volcanic activity and volatile release in Iceland and in global eruptive records. However, it is unclear whether this process is also important in magmatically-active systems that do not show evidence of enhanced eruption rates. For example, the deglaciation of the Yellowstone ice cap did not observably enhance volcanism, yet Yellowstone may still have released large volumes of CO2 to the surface due to the crystallization of melts at depth. Here we develop models to simulate mantle melt production and volatile release associated with the deglaciation of Yellowstone and Iceland. In agreement with previous work, we find mantle melt production in Iceland is enhanced 33-fold during deglaciation, generating an additional 3728 km3 of melt and releasing an additional 31–51 Gt of CO2. Beneath Yellowstone, we find mantle melt production is comparably enhanced 19-fold during deglaciation, generating an additional 815 km3 of melt, though thicker lithosphere may prevent the transport of this melt to the surface. These melts segregate an additional 135–230 Gt of CO2 from the mantle, representing a ~23–39% increase of the global volcanic CO2 flux (if degassed during deglaciation). Our results suggest deglaciation-enhanced mantle melting is important in continental settings with partially molten mantle (potentially Greenland and West Antarctica) and may result in positive feedbacks between deglaciation and climate warming.

Synthesis and Characterization of β-Cyclodextrin-Essential Oil Inclusion Complexes for Tick Repellent Development

Essential oils (EOs) are used in several pest management applications. Due to their volatility, EOs may experience bioactivity reduction, thus requiring protection to extend their properties. In the present study, we investigated the inclusion complex formation (IC) of β-cyclodextrin (β-CD) with selected EOs with known tick repellent activity using two co-precipitation methods. ICs were characterized by evaluating EO mass concentration and inclusion efficiency (% IE) and other instrumental methods. Co-precipitation method 2 yielded the highest EO mass concentration (88 ± 6 μg/mg β-CD) for the 1:1 molar ratio geranium Egyptian EO IC. The EO volatile release over time from the ICs was investigated by headspace SPME/GC-MS analysis. ICs were also tested in tick repellency bioassays. ICs reported significant tick repellent activity, with lemongrass IC performing best overall. Method 1 showed the best combination of high mass concentration EO, controlled volatile release, and tick repellency with lemongrass EO. The results demonstrated that β-CD had selectively encapsulated different EOs. Moreover, the formation of ICs may improve EO tick repellent properties protecting the active ingredients and providing a better, long-lasting repellent action. These findings will allow the development of more effective naturally derived repellent products to protect individuals from tick bites and prevent tick-borne illnesses.

Effects on the solubility and the volatile release from magmatic intrusions

<p>The process of fractional crystallization within a magma body has an influence on the solubility and thus on the associated release of volatiles. Nevertheless, this mechanism is widely neglected in the literature. Due to cooling of an intrusion, nominally anhydrous minerals precipitate from the melt. These minerals mainly incorporate elements that are compatible with their crystal lattice. Since volatiles such as H<sub>2</sub>O and CO<sub>2</sub> behave like incompatible elements, they accumulate in the remaining melt. At a certain point, the melt is saturated and the exsolution of the volatiles initiates. The solubility is determined by several parameters like the lithostatic and the partial pressure, the temperature and the melt composition. <br>In this study, we investigate the effect of these parameters as well as the impact of fractional crystallization on the solubility and the related volatile release. We focus on the exsolution of H<sub>2</sub>O and CO<sub>2</sub> from basaltic magma bodies within the lithosphere. To determine the fate of the accumulating volatiles, we compare the density of the developing liquid phase (volatiles and residual melt) with the density of the host rock. If the host rock has a higher density, the liquid phase will ascent either directly to the surface or to shallower levels of the crust. Furthermore, we take into account the possibility that hydrous minerals (e.g., amphibole) are precipitated during fractional crystallization or due to a reaction with the surrounding rock. </p>

Kinetics and thermodynamics evaluation of carbon dioxide enhanced oil shale pyrolysis

The pyrolysis process of oil shale is significantly affected by atmospheric conditions. In this paper, the pyrolysis experiments of oil shale under non-isothermal conditions are carried out using nitrogen and carbon dioxide as heat-carrying fluids. The results show that the activation energy of the second stage of oil shale pyrolysis under carbon dioxide is less than that under nitrogen. The thermodynamic analysis of the second stage of oil shale pyrolysis shows that Gibbs free energy, activation enthalpy and activation entropy are higher under carbon dioxide than those under nitrogen, which obeys the law of carbon dioxide promoting oil shale pyrolysis. In addition, the volatile release characteristics of oil shale in the second stage of pyrolysis were analyzed, which proves that the volatile release characteristics of oil shale under carbon dioxide are higher than that under nitrogen. Therefore, carbon dioxide is helpful to promote the pyrolysis of oil shale and increases the release of volatile substances during pyrolysis.