The use of nanoparticles has emerged as a popular amendment and promising approach to enhance plant resilience to environmental stressors, including salinity. Salinity stress is a critical issue in global agriculture, requiring strategies such as salt-tolerant crop varieties, soil amendments, and nanotechnology-based solutions to mitigate its effects. Therefore, this paper explores the role of plant-based titanium dioxide nanoparticles (nTiO2) in mitigating the effects of salinity stress on soybean phenotypic variation, water content, non-enzymatic antioxidants, malondialdehyde (MDA) and mineral contents. Both 0 and 30 ppm nTiO2 treatments were applied to the soybean plants, along with six salt concentrations (0, 25, 50, 100, 150, and 200 mM NaCl) and the combined effect of nTiO2 and salinity. Salinity decreased water content, chlorophyll and carotenoids which results in a significant decrement in the total fresh and dry weights. Treatment of control and NaCl treated plants by nTiO2 showed improvements in the vegetative growth of soybean plants by increasing its chlorophyll, water content and carbohydrates. Additionally, nTiO2 application boosted the accumulation of non-enzymatic antioxidants, contributing to reduced oxidative damage (less MDA). Notably, it also mitigated Na+ accumulation while promoting K+ and Mg++ uptake in both leaves and roots, essential for maintaining ion homeostasis and metabolic function. These results suggest that nTiO2 has the potential to improve salinity tolerance in soybean by maintaining proper ion balance and reducing MDA level, offering a promising strategy for crop management in saline-prone areas.

Antimony (Sb) is a potential threat to living organisms, but very little is known on strategies manage its toxicity in plants. This study aimed to clarify the role of Fe on alleviation Sb toxicity in a metallicolous population of Salvia spinose and its mechanisms. With regard to the toxicity of Sb in plants and the importance of Fe potential in alleviation of Sb toxicity, S. spinosa was treated with 0 and 27 mg l- 1 Sb (III or V) along with 0, 50 and 300 mu M FeEDTA in a hydroponic system. The plants exposure to iron minimized the uptake of both Sb species by Salvia roots. The limitation of H2O2 generation in response to co-application of Fe with Sb was followed by counterbalancing the antioxidant enzymes (e.g. catalase, superoxide dismutase and ascorbate peroxidase), phenols, flavonoids, lipid membrane preservation, and increase of the carbohydrates and proteins contents, which altogether improved growth in Sb-stressed plants. The Sb (III) toxicity to plants was much higher than Sb (V), but 300 mu M Fe was significantly efficient in reducing Sb damages to Salvia. Altogether, application of Fe could efficiently alleviate the physiological and morphological functions in Sb-stressed Salvia.

Permafrost regions of Qilian Mountains in China are rich in gas hydrate resources. Once greenhouse gases in deep frozen layer are released into the atmosphere during hydrate mining, a series of negative consequences occur. This study aims to evaluate the impact of hydrate thermal exploitation on regional permafrost and carbon budgets based on a multi-physical field coupling simulation. The results indicate that the permeability of the frozen soil is anisotropic, and the low permeability frozen layer can seal the methane gas in the natural state. Heat injection mining of hydrates causes the continuous melting of permafrost and the escape of methane gas, which transforms the regional permafrost from a carbon sink to a carbon source. A higher injection temperature concentrates the heat and causes uneven melting of the upper frozen layer, which provides a dominant channel for methane gas and results in increased methane emissions. However, dense heat injection wells cause more uniform melting of the lower permafrost layer, and the melting zone does not extend to the upper low permeability formation, which cannot provide advantageous channels for methane gas. Therefore, a reasonable and dense number of heat injection wells can reduce the risk of greenhouse gas emissions during hydrate exploitation.

Plants are subject to various abiotic stresses such as water shortage and exposure to heavy metals, such as Pb in soil. These types of stress trigger a series of plant responses, ranging from a decrease in leaf gas exchange, an increase in lipid peroxidation, and even changes in the chemical composition of leaves and roots. As an essential micronutrient, Fe is involved in several physiological and biochemical processes in plants, such as photosynthetic activity, directly participating in chlorophyll synthesis and electron transport, being necessary for the maintenance of the structure and functioning of chloroplasts. The main objective of this work was to evaluate the action of Fe in mitigating Pb toxicity in young plants of the CCN 51 cacao genotype, subjected to water deficit in the soil, through photosynthetic responses and analysis of the chemical composition of different parts of the plant. Plants were grown with Pb (2 mmol Pb kg-1 soil) and different equimolar doses of Pb+Fe in the soil (2+0.5, 2+1, 2+1.5 and 2+2 mmol kg(-1) soil), maintaining constant the Pb dose, whose soil was subjected to water deficit, with gradual reduction of water content, or its moisture was maintained near to field capacity, making a total of 12 treatments, together with the control treatment (without addition of Pb and Fe in soil). It was observed that the greater Fe absorbing, by the root system, mitigated the Pb toxicity. Fe application, in adequate dose in soil (2 mmol Pb kg-1 soil + 0.5 mmol Fe kg(-1) soil), mitigated the toxic effects caused by Pb and water deficit in the plants, through the greater Fe taking up and translocation for the shoot in Pb detriment. Greater Pb translocation and accumulation in the leaves caused damage to leaf gas exchange and to the accumulation of carbohydrates in leaves. Fe and Pb applied in soil competed with each other for root absorbing regardless of soil water conditions.

The objective of this study was to improve the physical and mechanical properties of adobes reinforced by cement-metakaolin mixtures. For this purpose, a raw clayey material from Burkina Faso consisting of kaolinite (62 wt%), quartz (30 wt%), and goethite (6 wt%) and belonging to the category of sandy-silty soils with medium plasticity has been used for adobe manufacturing. Metakaolin was produced by thermal activation of a local raw clayey material at 680 degrees C for 2 h. Adobes were first formulated with cement up to 12 wt%. It appears from this formulation that 10 and 12 wt% cement offer good mechanical strength elaborated adobes. Taking into account the high cost of cement in Burkina Faso, 10 wt% of cement was retained to be replaced by 2, 4, 6, 8, and 10 wt% metakaolin. The microstructural (by SEM-EDS), physical (apparent density, porosity, linear shrinkage, water absorption test by capillarity, spray test), and mechanical (compressive and flexural strengths) characteristics of formulated adobes were evaluated. The obtained results showed that this substitution improved adobe microstructure with pores reduction leading to composite densification. The presence of metakaolin slows down the phenomenon of capillary rise of water in adobes. Also, the metakaolin presence within the cementitious matrix improves the mechanical behavior and reduces rain erosion effect. The improvement of different properties was mainly due to formation of calcium silicate hydrates (CSH) resulting by cement hydration and metakaolin's pozzolanic reaction. Adobes reinforced with 6 wt% cement and 4 wt% metakaolin have suitable technological characteristics to be used as building materials for developing countries.

Sodium chloride is expected to be found on many of the surfaces of icy moons like Europa and Ganymede. However, spectral identification remains elusive as the known NaCl-bearing phases cannot match current observations, which require higher number of water of hydration. Working at relevant conditions for icy worlds, we report the characterization of three hyperhydrated sodium chloride (SC) hydrates, and refined two crystal structures [2NaCl center dot 17H(2)O (SC8.5); NaCl center dot 13H(2)O (SC13)]. We found that the dissociation of Na+ and Cl- ions within these crystal lattices allows for the high incorporation of water molecules and thus explain their hyperhydration. This finding suggests that a great diversity of hyperhydrated crystalline phases of common salts might be found at similar conditions. Thermodynamic constraints indicate that SC8.5 is stable at room pressure below 235 K, and it could be the most abundant NaCl hydrate on icy moon surfaces like Europa, Titan, Ganymede, Callisto, Enceladus, or Ceres. The finding of these hyperhydrated structures represents a major update to the H2O-NaCl phase diagram. These hyperhydrated structures provide an explanation for the mismatch between the remote observations of the surface of Europa and Ganymede and previously available data on NaCl solids. It also underlines the urgent need for mineralogical exploration and spectral data on hyperhydrates at relevant conditions to help future icy world exploration by space missions.

On the basis of results from exhaustive first-principles simulations, we report a thorough description of the recently identified high pressure phase of the CO2 hydrate, and provide an estimation of the transition pressure from the sI low pressure phase to the C-0 high pressure (HP) phase around 0.6 GPa. The vibrational properties calculated here for the first time might be useful to detect this HP structure in extraterrestrial environments, such as the Jupiter ice moons. Interestingly, we also find that CO2 gas molecules are quasi-free to diffuse along the helical channels of the structure, thus allowing the interchange of volatiles across a solid icy barrier. Taking into account its density and comparing it with other substances, we can estimate the naturally occurring zone of this CO2@H2O HP phase within a giant ice moon such as Ganymede. Other potential planetary implications that all of the found properties of this hydrate might have are also discussed.

Gas hydrates formed in oceans and permafrost occur in vast quantities on Earth representing both a massive potential fuel source and a large threat in climate forecasts. They have been predicted to be important on other bodies in our solar systems such as Enceladus, a moon of Saturn. CO2-hydrates likely drive the massive gas-rich water plumes seen and sampled by the spacecraft Cassini, and the source of these hydrates is thought to be due to buoyant gas hydrate particles. Dispersion forces can in some cases cause gas hydrates at thermal equilibrium to be coated in a 3-4 nm thick film of ice, or to contact water directly, depending on which gas they contain. As an example, the results are valid at a quadruple point of the water-CO2 gas hydrate system, where a film is formed not only for the model with pure ice but also in the presence of impurities in water or in the ice layer. These films are shown to significantly alter the properties of the gas hydrate clusters, for example, whether they float or sink. It is also expected to influence gas hydrate growth and gas leakage.

Air temperatures and precipitation are predicted to increase in the future, especially at high latitudes and particularly so during winter. In contrast to air temperatures, changes in soil temperatures are more difficult to predict, as the fate of the insulating snow cover is crucial in this respect. Soil conditions can also be affected by rain-on-snow events and warm spells during winter, resulting in freeze-thaw cycles, compacted snow, ice encasement and local flooding. These adverse conditions during winter could counteract the otherwise positive effects of climate change on forest growth and productivity. For studying the effects of different winter and snow conditions on young Downy birch (Betula pubescens Ehrh.) seedlings, we carried out a laboratory experiment with birch seedlings subjected to four different winter scenarios: snow covering the seedlings (SNOW), compressed snow and ice encasement (ICE), flooded and frozen soil (FLOOD) and no snow at all (NO SNOW). After the winter treatments we simulated a spring and early summer period of 9.5 weeks, and monitored the growth by measuring shoot and root biomass of the seedlings, and starch and soluble sugar concentrations. We also assessed the stress experienced by the seedlings by measuring leaf chlorophyll fluorescence and gas exchange. Although no difference in mortality was observed between the treatments, the seedlings in the SNOW and ICE treatments had significantly higher shoot and root biomass compared with those in the FLOOD and NO SNOW treatments. We found higher starch concentrations in roots of the seedlings in the SNOW and ICE treatments, compared with those in the FLOOD and NO SNOW treatments, although photosynthesis did not differ. Our results suggest a malfunction of carbohydrate distribution in the seedlings of the FLOOD and NO SNOW treatments, probably resulting from decreased sinks. The results underline the importance of an insulating and protecting snow cover for small tree seedlings, and that future winters with changed snow pattern might affect the growth of tree seedlings and thus possibly species composition and forest productivity.

Methane (CH4) is produced in many natural systems that are vulnerable to change under a warming climate, yet current CH4 budgets, as well as future shifts in CH4 emissions, have high uncertainties. Climate change has the potential to increase CH4 emissions from critical systems such as wetlands, marine and freshwater systems, permafrost, and methane hydrates, through shifts in temperature, hydrology, vegetation, landscape disturbance, and sea level rise. Increased CH4 emissions from these systems would in turn induce further climate change, resulting in a positive climate feedback. Here we synthesize biological, geochemical, and physically focused CH4 climate feedback literature, bringing together the key findings of these disciplines. We discuss environment-specific feedback processes, including the microbial, physical, and geochemical interlinkages and the timescales on which they operate, and present the current state of knowledge of CH4 climate feedbacks in the immediate and distant future. The important linkages between microbial activity and climate warming are discussed with the aim to better constrain the sensitivity of the CH4 cycle to future climate predictions. We determine that wetlands will form the majority of the CH4 climate feedback up to 2100. Beyond this timescale, CH4 emissions from marine and freshwater systems and permafrost environments could become more important. Significant CH4 emissions to the atmosphere from the dissociation of methane hydrates are not expected in the near future. Our key findings highlight the importance of quantifying whether CH4 consumption can counterbalance CH4 production under future climate scenarios. Plain Language Summary Methane is a powerful greenhouse gas, second only to carbon dioxide in its importance to climate change. Methane production in natural environments is controlled by factors that are themselves influenced by climate. Increased methane production can warm the Earth, which can in turn cause methane to be produced at a faster rate - this is called a positive climate feedback. Here we describe the most important natural environments for methane production that have the potential to produce a positive climate feedback. We discuss how these feedbacks may develop in the coming centuries under predicted climate warming using a cross-disciplinary approach. We emphasize the importance of considering methane dynamics at all scales, especially its production and consumption and the role microorganisms play in both these processes, to our understanding of current and future global methane emissions. Marrying large-scale geophysical studies with site-scale biogeochemical and microbial studies will be key to this.