Underground Hydrogen Storage (UHS) represents a pivotal pathway for establishing a global hydrogen economy and decarbonizing energy infrastructure, yet its practical efficacy remains constrained by complexities in hydrogen microscopic storage and transport mechanisms within subsurface reservoirs. Our review examines H2 adsorption and diffusion processes in subsurface porous media, integrating a comprehensive experimental framework for diffusion coefficient measurement. The results indicate that H2 adsorption is predominantly physical, with capacity modulated by temperature, pressure, moisture, reservoir properties, and competitive adsorption with CH4; Diffusion exhibits multiple mechanisms and influencing factors behavior, where H2 diffusivity exceeds that of CH4 and CO2 by orders of magnitude-though this enhances caprock leakage risks. Optimizing reservoir parameters and ensuring caprock integrity can substantially enhance UHS efficiency and operational safety. Nevertheless, future work must investigate long-term H2 depletion behavior and H2- fluidrock interactions.
The degradation of permafrost alters deformation and long-term strength, posing challenges to existing and future civil infrastructure in Northern Alaska. Long-term strength is a critical parameter in the design of civil projects; yet, to our best knowledge, data on the creep deformation and long-term strength of undisturbed permafrost in Northern Alaska remain limited. Soil particle fraction, unfrozen water content, temperature, and salinity may interactively affect creep deformation and long-term strength of permafrost; however, their interactive effects are not well understood. In this study, field samples of relatively undisturbed permafrost from the upper 1.5 m of the Arctic Coastal Plain near Utqia & gdot;vik, Alaska, were first retrieved and analyzed. The permafrost was characterized as saline ice-rich silty sand and nonuniformly distributed ice. We conducted constant stress creep tests, unconfined compression strength tests, and unfrozen water content tests to assess the mechanical and physical properties of the permafrost cores. The results indicated that the long-term strength of the permafrost decreased by nearly 90% from -10 degrees C to -2 degrees C. At -10 degrees C, the long-term strength increased by approximately 120% as the soil particle fraction rose from 0.14 to 0.26. The strengthening effect of soil particles diminished at higher temperatures and higher salinity due to the influence of unfrozen water. A quantitative tool has been developed to predict the long-term strength of ice-rich permafrost, incorporating the effects of soil particle fraction and temperature. The findings of this study can potentially support infrastructure design and planning in Northern Alaska in the context of a warming climate.
Effects on juvenile growth have long been considered an important benefit of parental care, but they have rarely been tested empirically. Protection and feeding by parents might accelerate offspring growth by allowing offspring to allocate more resources to growth (resource-allocation hypothesis). Protected young could shift investment away from defensive adaptations toward growth (defensive reallocation), and parental feeding should increase the total amount of assimilated resources (energy intake). Alternatively, rapid growth can be costly due to damage caused by reactive oxygen species, and parental protection might facilitate slower growth to avoid this (costly acceleration hypothesis). We tested these hypotheses along with the suggestion that egg and adult size are correlated with growth in a common-garden study of 17 species of carrion beetles (Silphinae, a subfamily of the beetle family Staphylinidae). Our results were consistent with the resource-allocation hypothesis but did not support the costly acceleration hypothesis or the idea that egg or adult size constrains growth. Species that are normally protected by parents grew faster, not slower, than those that are not. This was true even when their parents were removed and could not feed, supporting the concept of defensive reallocation. As expected based on greater energy intake, the young of species with parental feeding grew faster when their parents were present than when they were not. When phylogeny was accounted for, neither egg nor adult size was related to early growth rate.
Climatic extremes can impact the productivity of aquatic species, affecting ecosystems and fishery-dependent communities. Advances in climate products, such as gridded datasets and downscaled projections, may be useful for quantifying freshwater habitat conditions and predicting climate change effects on fish. However, limited guidance exists for selecting climate products to develop indicators of freshwater habitat conditions that influence fish population dynamics. Here, we develop an approach for identifying streamflow and stream temperature models to address this need. We evaluated skill in predicted versus observed streamflow and stream temperature, with predictions depending on different models and gridded climate data as inputs. The best performing models were used in a case study exploring habitat conditions influencing Chinook salmon in the Yukon and Kuskokwim River basins, two remote high-latitude watersheds with few in situ habitat observations and recent salmon declines. Three modeled streamflow datasets had variable performance (median Nash-Sutcliffe efficiencies from 0.39 to 0.70). Three gridded temperature products differed in their ability to explain variation in weekly stream temperatures (median r 2 from 0.42 to 0.76). We selected a single gridded air temperature dataset to compare two novel predictive stream temperature models, both of which had good accuracy (root mean squared error [RMSE] of 1.19 and 0.95 degrees C). Stream temperature indicators calculated from modeled daily data, maximum temperatures during adult migration and cumulative temperatures during juvenile rearing, had high spatial correlation across tributaries within the Yukon and Kuskokwim River basins and showed significant warming over the past 40 years. Streamflow indicators calculated from modeled daily data, maximum flow during spawning and median flow during rearing, had few trends and were largely uncorrelated within the Yukon River basin and moderately correlated within the Kuskokwim River basin. Overall, we found that generic measures of model performance varied considerably, and it was important to consider the models best suited to our case study. For both streamflow and stream temperature, multiple high-performing models allowed estimation of ecologically relevant conditions affecting Chinook salmon. The approach we used to estimate local-scale habitat conditions has value to identify synchronous conditions that may influence multiple salmon populations under a changing subarctic climate.
Oscillatory zoning — alternating high- and low-impurity (trace element) zones — is a hallmark of magmatic zircon from felsic systems and preserves the history of magmatic systems. Although commonly attributed to fluctuations in temperature, pressure, or melt composition, the mechanisms driving this zoning remain uncertain. Here, we show that high-impurity growth zones, which appear homogeneous when imaged with a scanning electron microscope (SEM), actually consist of finer-scale growth zones when viewed at the nanoscale - and still finer zones are revealed at the atomic scale. The apparent homogeneity in SEM images results from electron beam convolution, where features smaller than the beam’s interaction volume cannot be resolved. Backscattered electron images have higher spatial resolution than cathodoluminescent images, but high-impurity zones imaged with both are found to consist of finer zones at the atomic scale when imaged with atom probe tomography. Adjacent low-impurity zones are homogeneous across all scales. We interpret these observations as evidence of impurity poisoning during near-equilibrium zircon growth. Faceted crystal growth at low supersaturation leads to rejection of impurities, except for those allowed by equilibrium partitioning. Rejected impurities accumulate on the crystal surface, blocking normal incorporation of atoms and temporarily halting growth. When supersaturation exceeds a critical threshold, growth resumes, trapping the adsorbed impurities and forming a high-impurity zone. These findings not only help to resolve the origin of oscillatory zoning in zircon but also establish a generalizable mechanism of impurity poisoning during near-equilibrium crystal growth, redefining how mineral records are interpreted in igneous systems and beyond.
