Molybdenum (Mo) is an essential nutrient for almost all organisms. However, at high concentrations, it can be toxic to animals and plants. This study investigated the interactions of Mo(VI) with iron oxyhydroxides during ferrihydrite bioreduction in the presence of Fe(III)-reducing Geobacter sulfurreducens. Here, we showed that Mo concentration controlled ferrihydrite phase transformation, leading to Mo release. With the biotic reduction of ferrihydrite and Fe(II) production, Mo(VI) reduction and Mo(IV)O2 formation were observed for the first time, which further immobilized Mo after surface adsorption of Mo(VI). At low Mo levels (Mo/Fe molar ratios of 1–2%), sufficient Fe(II) adsorption onto ferrihydrite resulted in its transformation into magnetite nanoparticles (>80%, ∼25 nm), which catalyzed the reduction of Mo(VI) to form Mo(IV)O2 and immobilized Mo. Contrastingly, at high Mo concentrations (Mo/Fe molar ratios of 5–10%), Mo(VI)O42– adsorption onto ferrihydrite limited Fe(II) adsorption; subsequently, less magnetite (<8–12%) formed while more goethite (∼30–50%, width and length >15 and 100 nm, respectively) and siderite (∼20–30%, width and length >100 and 200 nm, respectively) with larger particle sizes formed instead, causing Mo(VI) release due to lower Mo adsorption. This study provides a comprehensive understanding of the interaction mechanisms among Geobacter sulfurreducens, Mo(VI), and iron oxyhydroxides, enabling predictions and controls of long-term Mo mobility and Fe mineral transformation under a variety of biogeochemical scenarios.
Understanding the nanoconfined water-CO2 interactions at the molecular scale is of great importance for the fluid transport in confined porous media. Here, a series typical water film and water bridge scenarios are determined, and the associated impacts on nanoconfined water-CO2 interactions as well as the geological hydrocarbon recovery and CO2 storage are investigated in nanopores. Our results confirm either in water film or water bridge scenarios, the competitive adsorptions of nanoconfined water and CO2 reduce the adsorbed water amount and derive the new water bridge with CO2 additions. Such a phenomenon indicates the substrate surface shifts from water-wet to partially CO2-wet, with lower fluid molecule diffusions and illite-water-CO2 sandwich-structured adsorption layer. Overall, our work investigates the mechanism of CO2 effects on distributions and aggregations of nanoconfined water molecules in nanopores, which also provides molecular-scale insights into the nanoconfined water-CO2 interactions in the processes of geological CO2 storage and utilization.
The transfer of farmland is an important area of rural development research; however, the impact of rural social networks has been neglected in studies. The aim of this study is to explore the effects, mechanisms, and heterogeneity of neighbors’ behavior on the process of land renting by farmers. Based on the data of the China Family Panel Studies in 2018, this research empirically analyzes the impact of community-level, local social interactions on the land rental behavior of farmers and its mechanisms using a spatial probit model. The results of this study indicate that neighbors’ land rental behavior positively and significantly affects that of other farmers in the same village. In addition, neighbors’ land rental encourages other farmers in the same village to follow suit through an increase in the perceived importance of the Internet among the farmers. In addition, there is heterogeneity in neighborhood influence. Notably, the impact of social networks on the renting out of the land by farmers, as evidenced in this study, is a key factor in accelerating the circulation of rural land and promoting rural development, thus contributing to the process of rural revitalization and its recording in the literature.
Nitrogen (N) is the most abundant element in Earth's atmosphere, but is extremely depleted in the silicate Earth. However, it is not clear whether core sequestration or early atmospheric loss was responsible for this depletion. Here we study the effect of core formation on the inventory of nitrogen using laser-heated diamond anvil cells. We find that, due to the simultaneous dissolution of oxygen in the metal, N becomes much less siderophile (iron-loving) at pressures and temperatures up to 104 GPa and 5000 K, a thermodynamic condition relevant to the bottom of the magma ocean in the aftermath of the moon-forming giant impact. Using a core–mantle–atmosphere coevolution model, we show that the impact-induced processes (core formation and/or atmospheric loss) are unlikely to account for the observed N anomaly, which is instead best explained by the accretion of mainly N-poor impactors. The terrestrial volatile pattern requires severe N depletion on precursor bodies, prior to their accretion to the proto-Earth.
ABSTRACT Climate change requires an immediate transition from fossil fuels to clean energy sources. Although hydrogen is considered a future energy source, over 90% of hydrogen is currently produced from fossil fuels, and large-scale renewable-fed hydrogen processes are limited by current technologies and economic processes. Therefore, hydrogen production from fossil fuels is a significant topic, particularly if fossil fuel-fed hydrogen production and utilization can be absolutely carbon-free. For the first time, this review critically discusses and analyzes the current advances and fundamentals of fossil fuel dehydrogenation from the perspective of techno-economic-environmental assessments while considering all potential fossil resources and hydrogen technology. This review concludes that the preference of fossil fuels for any hydrogen production technology is as follows: fossil gas > heavy fossil liquid > light fossil liquid > fossil minerals. Thermo-catalytic hydrocarbon decomposition can outperform most other hydrocarbon reforming and pyrolysis processes owing to its energy efficiency, economic effectiveness, and environmental friendliness. Further, we explore potentially new “green hydrogen” technology and confirm that fossil fuels could be completely decarbonized throughout the full-chain stages from exploration to production and consumption. Overall, this work reveals that fossil fuels can be utilized completely carbon-free and provides technical support for future fossil fuel dehydrogenation and energy decarbonization in academic research, industrial practice, and governmental strategies.
It is significant to accurately evaluate the relative permeability of oil–water two phase for multiphase seepage in porous media in low permeability and tight oil reservoir. However, stress sensitivity is an important characteristic for low permeability and tight oil reservoir. It is an effective way for fractal theory to describe the complexity and heterogeneity of the microstructure of porous media. To describe the relative permeability of oil–water two phase in porous media with complex and irregularity pores, a new relative permeability model oil–water two phases is proposed by the fractal theory and the stress sensitivity is taken into the established model in this paper. Meanwhile, the effects of effective stress, elastic modulus, porosity, maximum and minimum flow radius on oil–water relative permeability are analyzed. The new model is verified by comparing with the laboratory data and the results demonstrate that irreducible water and residual oil saturation have a negative correlation with effective stress. The relative permeability of the oil–water two-phase will shrink to the middle as the rise of effective stress, and the region of co-infiltration will decrease. The deformation quantity of porous media, irreducible water and residual oil saturation will increase as the elastic modulus decreases. The larger the maximum flow radius is, the lower the irreducible water saturation and residual oil saturation is. Both the porosity and the minimum flow radius have slight influences on the relative permeability of oil–water two-phase. The proposed relative permeability model can effectively predict the relative permeability of oil and water and help to describe and reveal the multiphase flow in porous media.