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Carbon capture and storage (CCS) is a developed technology to minimize CO2 emissions and reduce global climate change. Currently, shale gas formations are considered as a suitable target for CO2 sequestration projects predominantly due to their wide availability. Compared to conventional geological formations including saline aquifers and coal seams, depleted shale formations provide larger storage potential due to the high adsorption capacity of CO2 compared to methane in the shale formation. However, the injected CO2 causes possible geochemical interactions with the shale formation during storage applications and CO2 enhanced shale gas recovery (ESGR) processes. The CO2/shale interaction is a key factor for the efficiency of CO2 storage in shale formations, as it can significantly alter the shale properties. The formation of carbonic acid from CO2 dissolution is the main cause for the alterations in the physical, chemical and mechanical properties of the shale, which in return affects the storage capacity, pore properties, and fluid transport. Therefore, in this paper, the effect of CO2 exposure on shale properties is comprehensively reviewed, to gain an in-depth understanding of the impact of CO2/shale interaction on shale properties. This paper reviews the current knowledge of the CO2/shale interactions and describes the results achieved to date. The pore structure is one of the most affected properties by CO2/shale interactions; several scholars indicated that the differences in mineral composition for shales would result in wide variations in pore structure system. A noticeable reduction in specific surface area of shales was observed after CO2 treatment, which in the long-term could decrease CO2 adsorption capacity, affecting the CO2 storage efficiency. Other factors including shale sedimentary, pressure and temperature can also alter the pore system and decrease the shale “caprock” seal efficiency. Similarly, the alteration in shales’ surface chemistry and functional species after CO2 treatment may increase the adsorption capacity of CO2, impacting the overall storage potential in shales. Furthermore, the injection of CO2 into shales may also influence the wetting behavior. Surface wettability is mainly affected by the presented minerals in shale, and less affected by brine salinity, temperature, organic content, and thermal maturity. Mainly, shales have strong water-wetting behavior in the presence of hydrocarbons, however, the alteration in shale’s wettability towards CO2-wet will significantly minimize CO2 storage capacities, and affect the sealing efficiency of caprock. The CO2/shale interactions were also found to cause noticeable degradation in shales’ mechanical properties. CO2 injection can weaken shale, decrease its brittleness and increases its plasticity and toughness. Various reductions in tri-axial compressive strength, tensile strength, and the elastic modulus of shales were observed after CO2 injection, due to the dissolution effect and adsorption strain within the pores. Based on this review, we conclude that CO2/shale interaction is a significant factor for the efficiency of CCS. However, due to the heterogeneity of shales, further studies are needed to include various shale formations and identify how different shales’ mineralogy could affect the CO2 storage capacity in the long-term.

In nearly all reservoirs, storage capacity is steadily lost due to trapping and accumulation of sediment. Despite critical importance to freshwater supplies, reservoir sedimentation rates are poorly understood due to sparse bathymetry survey data and challenges in modeling sedimentation sequestration. Here, we proposed a novel approach to estimate reservoir sedimentation rates and storage capacity losses using high‐resolution Sentinel‐2 satellites and daily in situ water levels. Validated on eight reservoirs across the central and western United States, the estimated reservoir bathymetry and sedimentation rates have a mean error of 4.08% and 0.05% yr−1, respectively. Estimated storage capacity losses to sediment vary among reservoirs, which overall agrees with the pattern from survey data. We also demonstrated the potential applications of the proposed approach to ungauged reservoirs by combining Sentinel‐2 with sub‐monthly water levels from recent satellite altimeters. Plain Language Summary Reservoir storage capacity is steadily lost due to sediment filling, which threatens freshwater supplies both now and in the future. Yet, lost reservoir storage capacities to sediment are largely unknown. Here, we develop a generic method to estimate capacity losses and reservoir sedimentation rates by leveraging remote sensing techniques. We tested on eight reservoirs across the central and western United States and found capacity losses and sedimentation rates vary across reservoirs. The proposed method offers a promising alternative to evaluate and predict capacity losses in reservoirs nationwide and globally, and thus supports effective water managements and planning for sustainable freshwater supplies in the future. Key Points High‐resolution Sentinel‐2 images and daily in situ water levels were used to estimate reservoir sedimentation rates and capacity losses Estimated reservoir sedimentation rates and storage capacity losses have a mean error of 0.05% yr−1 of full storage capacity Potential applications of this method to ungauged reservoirs are feasible with sub‐monthly level data from recent satellite altimeters

Prospective use of perovskite hydride materials in H storage a crucial element of clean energy systems has drawn a lot of attention. The structural, electrical, mechanical, thermodynamic, and H storage qualities of Na 2 CaCdH 6 hydride alloys were examined in this work using DFT. According to the structural properties, Na 2 CaCdH 6 has space group 225 (Fm3m), and optimized lattice parameters and volume of Na 2 CaCdH 6 are 3.3485 Å and 593.764 Å 3 . The measured gravimetric H storage capacity of Na 2 CaCdH 6 hydrides is 2.956 wt%. The hydrides under research are semiconductors, as indicated by the computed electronic characteristics. Elastic constants, Pugh’s ratio, modulus, Poisson’s ratio, anisotropic, and microhardness of Na 2 CaCdH 6 are calculated under mechanical properties. The hydrides are dynamically stable, as indicated by the phonon dispersion curves, but mechanically stable according to the Born criterion for elastic constant (C ij ). The Cauchy’s pressure (C″ = 7.836) revealed the ductile behavior. The electronic and mechanical characteristics imply that Na 2 CaCdH 6 hydride can conduct electricity and is also mechanically stable. Our findings shed light on the possibilities of Na 2 CaCdH 6 perovskite hydride material for H storage utilization.

Water storage capacity in the layers of canopy, litter, and soil of forest ecosystems has not yet been thoroughly investigated on a global scale. We estimated the global pattern of water storage capacity of forest ecosystems related to water regulation services (WSCFE) in the above three layers based on 1,288 observations and analyzed their 22 controlling environmental factors. The results show that the global mean WSCFE per unit area is 456.7 mm, and the total volume of WSCFE is 22,662.5 km3. Climatic variables are the leading factors contributing to the variations of WSCFE, followed by forest attributes, terrain factors, soil properties, and litter characteristics. This study advances the understanding of the large‐scale variation mechanisms of WSCFE in different forest types and climate zones and provides scientific evidence for ecological protection according to local conditions. Plain Language Summary Forest ecosystem plays a vital role in the earth's hydrological process, and water storage capacity of forest ecosystems related to water regulation service (WSCFE) is of vital importance for human well‐being. Water can be intercepted by forest canopy, be held by litter, and be stored in soils, which accounts for more than a quarter of the water volumes in the terrestrial hydrologic cycle. The WSCFE is affected by many factors and its global pattern has not been well understood. In this study, based on the observed data from literature, we provided a robust global pattern of the WSCFE in canopy layer, litter layer, and soil layer. The results show that the WSCFE in the canopy and soil layer decrease gradually from tropical climate zone to polar climate zone, while the maximum WSCFE in the litter layer appears in polar and cold climate zone. The main controlling factors have different impacts on the WSCFE in the three layers. These should be considered in the developing protection policies for important ecological functional areas. Key Points Forest water storage capacity related to water regulation decreases from equator to pole, from coast to inland, and from mountains to plains Among the controlling factors, climatic factors have the largest and most positive influence on water storage capacity The quantification of three important water storages provides a basis to delineate global water regulation zones

Shape-memory polymers (SMPs) show great potential in various emerging applications, such as artificial muscles, soft actuators, and biomedical devices, owing to their unique shape recovery-induced contraction force. However, the factors influencing this force remain unclear. Herein, we designed a simple polymer blending system using a series of tetra-branched poly(ε-caprolactone)-based SMPs with long and short branch-chain lengths that demonstrate decreased crystallinity and increased crosslinking density gradients. The resultant polymer blends possessed mechanical properties manipulable across a wide range in accordance with the crystallinity gradient, such as stretchability (50.5–1419.5%) and toughness (0.62–130.4 MJ m−3), while maintaining excellent shape-memory properties. The experimental results show that crosslinking density affected the shape recovery force, which correlates to the SMPs’ energy storage capacity. Such a polymer blending system could provide new insights on how crystallinity and crosslinking density affect macroscopic thermal and mechanical properties as well as the shape recovery force of SMP networks, improving design capability for future applications.

Many major cities worldwide have inevitably experienced excessive groundwater pumping due to growing demands for freshwater in urban development. To mitigate land subsidence problems during urbanization, various regulations have been adopted to control groundwater usage. This study examines the transition in the post‐subsidence stage, especially in metropolitan areas, to adaptively adjust subsidence prevention strategies for effective groundwater management. Taking the Taipei Basin as an example, historical data reveals significant subsidence of more than 2 m during early urban development, with subsidence hazards largely mitigated over decades. However, the rising groundwater level poses a risk to the stability of engineering excavations. In this study, 29 X‐band Cosmo‐Skymed constellation (CSK) images were utilized with the Persistent Scatterer InSAR (PSInSAR/PSI) technique to monitor surface displacements during the construction of the Mass Rapid Transit system. Correlating groundwater levels helps identify the heterogeneous hydrogeological environment, and the potential groundwater capacity is assessed. PSI time‐series reveal that approximately 2 cm of recoverable land displacements correspond to groundwater fluctuations in the confined aquifer, indicative of the typically elastic behavior of the resilient aquifer system. The estimated groundwater storage variation is about 1.6 million cubic meters, suggesting this potential groundwater capacity could provide available water resources with proper management. Additionally, engineering excavation safety can be ensured with lowered groundwater levels. This study emphasizes the need to balance groundwater resource use with urban development by adjusting subsidence prevention and control strategies to achieve sustainable water management in the post‐subsidence stage. Plain Language Summary Groundwater is used as an important freshwater resource in global urban development, but over‐exploitation often leads to subsidence problems. Once land subsidence situation is under controlled, attention turns to how to balance urban development with environmental protection. This study takes a metropolitan area in a post‐subsidence period as an example and uses satellite technique to estimate potential groundwater volumes. It suggests that with proper management, groundwater resources can be fully utilized and related engineering disasters can be prevented. Key Points Integrating InSAR and numerical model for transient‐like state groundwater level mapping Quantifying changes in potential groundwater storage as available freshwater resources Efficient groundwater utilization for achieving sustainability in post‐subsidence stages

Vegetation roots play an essential role in regulating the hydrological cycle by removing water from the subsurface and releasing it to the atmosphere. However, the present understanding of the drivers of ecosystem-scale root development and their spatial variability globally is limited. This study investigates the varying roles of climate, landscape, and vegetation on the magnitude of root zone storage capacity ( Sr) worldwide, which is defined as the maximum volume of subsurface moisture accessible to vegetation roots. To this aim, we quantified Sr and evaluated 21 possible climate, landscape, and vegetation controls for 3612 river catchments worldwide using a random forest machine learning model. Our findings reveal climate as primary, but spatially varying, driver of ecosystem scale Sr with landscape and vegetation characteristics playing a minor role. More specifically, we found the mean inter-storm duration as most dominant control of Sr globally, followed by mean temperature, mean precipitation, and mean topographic slope. While the inter-storm duration, temperature, and slope exhibit a consistent relation with Sr globally, the relation between precipitation and Sr varies spatially. Based on this spatial variability, we classified two different regimes: precipitation driven and energy limited. The precipitation-driven regime exhibits a positive relation between precipitation and Sr for precipitation of up to 3 mmd−1, above which the relation flattens and eventually becomes negative. The energy-limited regime exhibits a strictly negative relation between precipitation and Sr. Using the random forest model based on these three dominant climate variables and the landscape variable slope, we generated a global gridded dataset of Sr, which closely resembles other global datasets of root characteristics. This suggests that our parsimonious approach based on four globally available variables to estimate Sr on a global scale has the potential to be readily and easily integrated into the parameterization of Sr in global hydrological and land surface models. This may enhance the accuracy of global predictions of land–atmosphere exchange fluxes and hydrological extremes by providing a robust representation of both spatial and temporal variability in vegetation root characteristics.

1. Optimal resource partitioning theory predicts that plants should increase the ratio between water absorbing and transpiring surfaces under short water supply. An increase in fine root mass and surface area relative to leaf area has frequently been found in herbaceous plants, but supporting evidence from mature trees is scarce and several results are contradictory. 2. In 12 mature Fagus sylvatica forests across a precipitation gradient (820-540 mm yr⁻¹), we tested several predictions of the theory by analysing the dependence of standing fine root biomass, fine root production and fine root morphology on mean annual precipitation (MAP), the precipitation of the study year, and stand structural and edaphic variables. The water storage capacity of the soil (WSC) was included as a covariable by comparing pairs of stands on sandy (lower WSC) and loam-richer soils (higher WSC). 3. Fine root biomass, total fine root surface area, fine root production and the fine root : leaf biomass production ratio markedly increased with reduced MAP and precipitation in the study year, while WSC was only a secondary factor and stand structure had no effect. 4. The precipitation effect on fine root biomass and production was more pronounced in stands on sandy soil with lower WSC, which had, at equal precipitation, a higher fine root biomass and productivity than stands on loam-richer soil. 5. The high degree of allocational plasticity in mature F. sylvatica trees contrasts with a low morphological plasticity of the fine roots. On the more extreme sandy soils, a significant decrease in mean fine root diameter and increase in specific root area with decreasing precipitation were found; a similar effect was absent on the loam-richer soils. 6. Synthesis. In support of optimal partitioning theory, mature Fagus sylvatica trees showed a remarkable allocational plasticity as a long-term response to significant precipitation reduction with a large increase in the size and productivity of the fine root system, while only minor adaptive modifications occurred in root morphology. More severe summer droughts in a future warmer climate may substantially alter the above-/below-ground C partitioning of this tree species with major implications for the forest C cycle.

An analytical model is developed for mean annual groundwater evapotranspiration (GWET) at the watershed scale based on a three‐stage precipitation partitioning framework. The ratio of mean annual GWET to precipitation, defined as GWET ratio, is modeled as a function of climate aridity index (CAI), storage capacity index, the shape parameter ‘a’ for the spatial distribution of storage capacity, and the shape parameter ‘b’ for the spatial distribution of available water for GWET. In humid regions, GWET ratio tends to increase with increasing CAI due to the limited energy supply and shallower depth to water table (DWT) for a given storage capacity index. In contrast, in arid regions, the GWET ratio tends to decrease as the CAI increases because of the limited water availability and the presence of a deeper DWT for a given storage capacity index. In arid regions, the GWET ratio decreases as the parameter ‘a’ increases, mainly because of increased ET from a thicker unsaturated zone in environments with a deeper DWT. GWET ratio increases as parameter ‘b’ increases due to more watershed area with larger available water for GWET. The storage capacity index and shape parameters are estimated for 31 study watersheds in Tampa Bay Florida area based on the simulated GWET from an integrated hydrologic model and for 21 watersheds from literature. A possible correlation has been identified between the two shape parameters in the Tampa Bay watersheds. The analytical model for mean annual GWET can be further tested in other watersheds if data are available. Key Points Mean annual groundwater evapotranspiration (GWET) is modeled by analytical equations through a three‐stage partitioning framework Mean annual GWET increases initially and then declines with increase in climate aridity index for given parameter values Shallow groundwater table in west‐central Florida results in similar spatial distributions of storage capacity and available water for GWET

In Mediterranean-type climates, asynchronicity between energy and water availability means that ecosystems rely heavily on the water-storing capacity of the subsurface to sustain plant water use over the summer dry season. The root-zone water storage capacity ( Smax [L]) defines the maximum volume of water that can be stored in plant accessible locations in the subsurface, but is poorly characterized and difficult to measure at large scales. Here, we develop an ecohydrological modeling framework to describe how Smax mediates root zone water storage (S [L]), and thus dry season plant water use. The model reveals that where Smax is high relative to mean annual rainfall, S is not fully replenished in all years, and root-zone water storage and therefore plant water use are sensitive to annual rainfall. Conversely, where Smax is low, S is replenished in most years but can be depleted rapidly between storm events, increasing plant sensitivity to rainfall patterns at the end of the wet season. In contrast to both the high and low Smax cases, landscapes with intermediate Smax values are predicted to minimize variability in dry season evapotranspiration. These diverse plant behaviors enable a mapping between time variations in precipitation, evapotranspiration and Smax, which makes it possible to estimate Smax using remotely sensed vegetation data − that is, using plants as sensors. We test the model using observations of Smax in soils and weathered bedrock at two sites in the Northern California Coast Ranges. Accurate model performance at these sites, which exhibit strongly contrasting weathering profiles, demonstrates the method is robust across diverse plant communities, and modes of storage and runoff generation.