Water Vapor Pressure Research Articles

Comprehensive Effects of Atmosphere and Soil Drying on Stomatal Behavior of Different Plant Types

The soil water supply and atmospheric humidity conditions are crucial in controlling plants’ stomatal behavior and water use efficiency. When there is water stress caused by an increase in saturated water vapor pressure (VPD) and a decrease in soil water content (SWC), plants tend to close stomata to reduce water loss. This affects the gross primary productivity (GPP) and evapotranspiration (ET), subsequently leading to changes in water use efficiency (WUE) and carbon use efficiency (CUE) in plants. However, land–atmosphere interactions mean that water vapor in the atmosphere and soil moisture content causing water stress for plants are closely related. This study aims to compare and estimate the effects of VPD and SWC on the carbon cycle and water cycle for different plant functional types. Based on the fluxnet2015 dataset from around the world, the WUE and CUE of five plant functional types (PFTs) were estimated under varying levels of VPD and SWC. The results showed that high VPD and low SWC limit the stomatal conductance (Gs) and gross primary productivity (GPP) of plants. However, certain types of vegetation (crops, broad-leaved forests) could partially offset the negative effects of high VPD with higher SWC. Notably, higher SWC could even alleviate limitations and partially promote the increase in GPP and net primary production (NPP) with increasing VPD. WUE and CUE were directly affected by Gs and productivity. In general, the increase in VPD in the five PFTs was the dominant factor in changing WUE and CUE. The impact of SWC limitations on CUE was minimal, with an overall impact of only −0.05μmol/μmol on the four PFTs. However, the CUE of savanna plants changed differently from the other four PFTs. The rise in VPD dominated the changes in CUE, and there was an upward trend as SWC declined, indicating that the increase in VPD and decrease in SWC promote the increase in the CUE of savanna plants to some extent.

Interspecific Differences of Stem Diameter Variations in Response to Water Conditions for Six Tree Species in Northeast China

It is important to understand the response of stem diameter variations in dominant tree species to water conditions in Northeast China. The results will provide basic information for scientific predictions of the future development trend of temperate forests in the eastern mountainous area of northeast China. We employed a high-precision dendrometer to continuously monitor the stem radial changes of six dominant tree species in temperate forests in northeast China from 15 April to 24 October in 2021. Precipitation significantly promoted the tree stem diameter increment. The increment of stem diameter in Juglans mandshurica Maxim., Quercus mongolica Fisch. and Betula platyphylla Suk. had a significantly positive correlation with cumulative precipitation. Correlation analysis revealed that the stem radial change (SRC) of six tree species was positively correlated with precipitation (Pre) and relative humidity (RH), and negatively correlated with water vapor pressure deficit (VPD), indicating that the diameter growth of the six tree species was mainly restricted by water conditions. Under drought stress, the stem radial growth rate of the six tree species slowed down, the growth duration decreased and the tree water deficit (TWD) value increased, while there were obvious interspecific differences. Therefore, water conditions limited the stem radial growth of the six tree species, while each tree species had a different response to drought stress.

Environmental drivers of the current and future distribution of high-yielding lacquer trees (Toxicodendron vernicifluum (stokes) F. A. Barkley)

Abstract Lacquer trees (Toxicodendron vernicifluum (Stokes) F.A. Barkley) are an important natural resource with significant economic and cultural value in East Asia. The main product, raw lacquer, is in high demand due to its commercially valuable characteristics. This study analyzed environmental drivers of the current and future distribution of lacquer trees in high-yielding locations using a machine-learning algorithm and Maxent models. Results identified suitable value ranges for four key environmental variables and their relative contribution to environmentally suitable areas (shown as percentages in parentheses): solar radiation, 12 000–13 000 kJ m−2 day−1 (43.1 per cent); min temperature of the coldest month, −3.5 to 3°C (18.7 per cent); annual precipitation, 900–1400 mm (13.9 per cent) and water vapour pressure, 1.2–1.6 KPa (5.1 per cent). Overall, projected climate change until 2100 will reduce the extent of environments suitable for high-yielding lacquer trees in China and the Republic of Korea, although these areas will expand in Japan. In addition to the three East Asian countries in which lacquer trees and production are currently important, the study identified environmentally suitable areas for growing lacquer trees in other countries worldwide under future climate conditions. The study’s methodology, which divided high-yielding records from other occurrence records and modeled them separately, was applicable in analyzing environmental drivers and modelling suitable areas for lacquer trees. This approach may also be beneficial to study the distributions of other plants, especially economically important crops and trees. In future studies, additional data sets capturing anthropogenic drivers and information on single tree level could further improve models exploring the productivity and sustainability of lacquer trees under future climates.

Competitive adsorption and selectivity of water vapor/R134a on activated carbon for indoor air purification

As an efficient tracer gas of activated carbon filter quality testing, the use of R134a is limited by relative humidity (RH) due to water vapor competitive adsorption. To analyze the competitive effect, the isosteric heats between vapor and ASZMT were calculated by C–C equation, the adsorption selectivity was predicted using the DIH method, and the binary adsorption equilibrium of water vapor and R134a on ASZMT were investigated via IAST model. Results showed that water vapor exhibited a higher isosteric heat than R134a at the same adsorption capacity, indicating a stronger interaction with ASZMT. The water vapor/R134a adsorption selectivity on ASZMT increases from 0 to 6.6, proving that the ASZMT is more selective for water vapor than R134a with water vapor pressure increasing. Besides, with water vapor pressure ratio improving, the R134a adsorption capacity on ASZMT decreases obviously, but water vapor adsorption capacity keeps increasing continuously. R134a breakthrough curves (1000 ppm) also showed that with relative humidity increasing, the R134a breakthrough times and dynamic adsorption capacities both became shorter, from 15 min to 9 min and from 6.68 mg/g to 1.49 mg/g, respectively. It proves that R134a and water vapor have obvious competitive adsorption behavior which is mainly dominated by water vapor concentration. It is necessary for ppm-level R134a to control the lower relative humidity of airflow in application.

All-in-One Configured Flexible Supercapacitor for Wide-Temperature Operation and Integrated Application

The advantages of stretchable supercapacitors (SCs), such as fast charging and discharging speed, high power density, and long cycle life, have attracted the research interest of many researchers. However, conventional SCs have limited applications in energy storage devices due to their unsatisfactory environmental tolerance, easy detachment of electrodes and electrolytes, and poor stretchability. In this work, a poly(vinyl alcohol) (PVA)–(acrylic acid) (AA) double-network hydrogel electrolyte was prepared by a one-pot method, followed by in situ polymerization of aniline (PANI) to fabricate all-in-one polyaniline SCs (PANI-SCs) devices. Multiple hydrogen bonds and in situ polymerization of PANI and dimethyl sulfoxide (DMSO) endow the PANI-SCs integrated, flexible SCs with good mechanical properties and electrochemical performance in a wide temperature range. The PANI-SCs device exhibits an excellent tensile elongation strain of 413.7% and a mechanical strength of 137.1 kPa. At room temperature, the areal capacitance of the PANI-SCs device is 48.1 mF cm–2. PANI-SCs contains a DMSO component; DMSO lowers the saturated vapor pressure of water to lower its freezing point and suppress the formation of ice crystallites and exhibits normal electrochemical performance over a wide temperature range of −80 to 100 °C. PANI-SCs drive LED lights and integrate with sensors for human health monitoring applications. Potential applications extend the development of flexible SCs in wearable electronics.

Thermogravimetric approach to efflorescence of sodium carbonate decahydrate

The efflorescence of sodium carbonate decahydrate (SC-DH), characterized by the solid-state thermal dehydration to form its monohydrate (SC-MH), occurs below its melting point positioned slightly above room temperature and at a lower atmospheric water vapor pressure (p(H2O)). Applying a thermogravimetry (TG) that covers temperatures lower than room temperature enabled us to systematically trace the efflorescence of SC-DH under various heating programs in a dry N2 stream, using which the kinetics of the efflorescence was formally described by the basic kinetic equation. Meanwhile, when the sample temperature reached the melting point of SC-DH midway through the efflorescence process, the thermal dehydration switched from solid-state mode to liquid-state one and exhibited a complex multistep mass loss behavior to form SC-MH. The multistep mass loss behavior and its changes with the reaction conditions were overviewed using a humidity-controlled TG at various atmospheric p(H2O).

Remote Sensing Monitoring Model of Tobacco Growth and Yield Based on Ecological Process and Carbon Cycle

Tobacco growth monitoring and yield estimation are very important for tobacco planting control and allocation. However, traditional tobacco yield estimation models have not considered the light energy utilization, carbon cycle, and ecological processes, resulting in the mechanisms poorly explained and the reduced monitoring accuracy. To address these limitations, a tobacco yield remote sensing monitoring model based on ecological process and carbon cycle was proposed. The model couples the Carbon Exchange between Vegetation, Soil, and Atmosphere (CEVSA) ecosystem process model and the global production efficiency model (GLO-PEM), to simulate effective solar radiation and tobacco light energy utilization, stress effects of surface air temperature, water vapour pressure deficit and photosynthetic effective radiation. Then the tobacco gross primary production (GPP), net primary productivity (NPP), tobacco biomass were estimated. Finally, the tobacco yield estimation model based on the correlation between tobacco yield and NPP was proposed. The results showed that there was a significant correlation (correlation= 0.94) between NPP and tobacco leaves weight at 99% confidence level, and the yield estimated by the remote sensing monitoring model was in good agreement with the measured results, with errors of Class I, II, III were 9.644%, 4.316%, and 8.495% respectively. In conclusion, the proposed model can be used to estimate tobacco yield, support decision-making of tobacco planting plan, and strengthen purchasing management.

Removing gas-phase features in near ambient pressure partial Auger-Meitner electron yield oxygen K-edge NEXAFS spectra

With the advent of ambient pressure X-ray excited electron spectroscopy, near-edge X-ray absorption fine structure spectroscopy is widely used to investigate the hydrogen-bonding environment in aqueous solutions, ice, and adsorbed water. When Auger-Meitner electrons are detected, the method becomes inherently surface-sensitive because of the limited escape depth of electrons. In such X-ray absorption experiments with aqueous samples, gas-phase water is inevitably present. It impacts the acquired spectra in two ways: (1) Absorption along the X-ray path upstream of the sample reduces the photon flux reaching the condensed phase. (2) Spectra originating from gas-phase water in front of the analyzer contribute to the recorded spectra. Here, we develop and discuss a procedure to disentangle the gas-phase and condensed-phase contribution in the acquired spectra. A novel approach to quantify and remove the gas-phase contribution allows receiving condensed-phase near-edge X-ray absorption fine structure spectra at high water vapor pressure free of gas-phase artifacts.

Trees with anisohydric behavior as main drivers of nocturnal evapotranspiration in a tropical mountain rainforest.

This study addresses transpiration in a tropical evergreen mountain forest in the Ecuadorian Andes from the leaf to the stand level, with emphasis on nocturnal plant-water relations. The stand level: Evapotranspiration (ET) measured over 12 months with the Eddy-Covariance (ECov) technique proved as the major share (79%) of water received from precipitation. Irrespective of the humid climate, the vegetation transpired day and night. On average, 15.3% of the total daily ET were due to nocturnal transpiration. Short spells of drought increased daily ET, mainly by enhanced nighttime transpiration. Following leaf transpiration rather than air temperature and atmospheric water vapor deficit, ET showed its maximum already in the morning hours. The tree level: Due to the humid climate, the total water consumption of trees was generally low. Nevertheless, xylem sap flux measurements separated the investigated tree species into a group showing relatively high and another one with low sap flux rates. The leaf level: Transpiration rates of Tapirira guianensis, a member of the high-flux-rate group, were more than twice those of Ocotea aciphylla, a representative of the group showing low sap flux rates. Representatives of the Tapirira group operated at a relatively high leaf water potential but with a considerable diurnal amplitude, while the leaves of the Ocotea group showed low water potential and small diurnal fluctuations. Overall, the Tapirira group performed anisohydrically and the Ocotea group isohydrically. Grouping of the tree species by their water relations complied with the extents of the diurnal stem circumference fluctuations. Nighttime transpiration and hydrological type: In contrast to the isohydrically performing trees of the Ocotea group, the anisohydric trees showed considerable water vapour pressure deficit (VPD)-dependent nocturnal transpiration. Therefore, we conclude that nighttime ET at the forest level is mainly sourced by the tree species with anisohydric performance.

Региональные особенности изменения норм основных климатических параметров на территории России

The regional features of changes in the normals of the main climatic parameters (air temperature, precipitation, water vapor tension, sea level pressure) on the territory of Russia are studied for three 30-year periods: 1961–1990, 1981–2010, and 1991–2020. Climate normals are calculated in accordance with the WMO requirements. In addition to the difference in the normals for stations, the values averaged over the territory of quasihomogeneous climatic regions are calculated. Seasonal changes in the regime of the main climatic parameters in certain regions of Russia over the past decades are revealed. In the last thirty years, a slowdown in warming in all seasons has been revealed on the territory of Russia. Summer precipitation normals for 1991–2020 decreased in most of the country, however, a significant increase in precipitation was found in the southern regions of Yakutia, the Amur region, and Primorye. For the regime of sea level pressure, the greatest changes are revealed in winter. The differences in climatic normals obtained in the present study can be considered as one of the indicators of climate change that are differently manifested in different regions of Russia. The information can be useful for developing preventive adaptation measures under changing climate. Keywords: climate, climate normal, air temperature, precipitation, air pressure, partial water vapor pressure, regional features

Phase equilibria, structural and thermodynamic properties of phases in the nickel (II) methanesulfonate – Water, cobalt (II) methanesulfonate – Water and manganese (II) methanesulfonate – Water systems

Solid-liquid equilibria in the Ni(CH3SO3)2-H2O, Co(CH3SO3)2-H2O, and Mn(CH3SO3)2-H2O systems were studied by isothermal solubility and DSC methods. TG and X-Ray diffraction were used to identify solid phases in equilibria with the solution. Water vapor pressure was determined by static method at 288.15 К, 298.15, and 308.15 K in the Ni(CH3SO3)2-H2O, Co(CH3SO3)2-H2O and Mn(CH3SO3)2-H2O systems. Based on vapor–liquid (VLE) and solid–liquid (SLE) equilibria data, parameters of the Pitzer-Simonson-Clegg model were obtained. Stability parameters of the hydrates Ni(CH3SO3)2·12H2O, Ni(CH3SO3)2·6H2O, Co(CH3SO3)2·4H2O, Co(CH3SO3)2·9H2O, Co(CH3SO3)2·6H2O, Mn(CH3SO3)2·12H2O, and Mn(CH3SO3)2·2H2O were estimated. Binary phase diagram fragments were calculated.

Wet to Dry Controls Lanthanide Scandate Synthesis

The choice of temperature and gas conditions used in a water pressure-controlled reactor is guided by density functional theory (DFT) to synthesize nearly phase-pure lanthanide scandate nanoparticles (LnScO3, Ln = La, Nd, Sm, Gd). In this synthetic method, low water-vapor partial pressures, well below water's gas liquidus, inhibit particle growth, while an excess of water vapor results in undesired rare-earth hydroxide and oxyhydroxide secondary phases. The optimal humidity for high-purity LnScO3 particle synthesis is shown to vary with the lanthanide; DFT is used to calculate the thermodynamics of secondary phase formation for each lanthanide tested such that the role of water vapor may be quantified and used to maintain phase purity (greater than 96 mol %) across the series. The combination of thermodynamic calculation and experimental confirmation with this pressure-controlled reactor provides an opportunity to explore analogous syntheses of other inorganic perovskite nanoparticles.

On the importance of the atmospheric coupling to the small-scale ocean in the modulation of latent heat flux

In this study, ocean and atmosphere satellite observations, an atmospheric reanalysis and a set of regional numerical simulations of the lower atmosphere are used to assess the coupling between the sea-surface temperature (SST) and the marine atmospheric boundary layer (MABL) as well as the latent heat flux (LHF) sensitivity to SST in the north-west tropical Atlantic Ocean. The results suggest that the SST-MABL coupling depends on the spatial scale of interest. At scales larger than the ocean mesoscale (larger than 150 km), negative correlations are observed between near-surface wind speed (U10m) and SST and positive correlations between near-surface specific humidity (q2m) and SST. However, when smaller scales (1 – 150 km, i.e., encompassing the ocean mesoscale and a portion of the submesoscale) are considered, U10m-SST correlate inversely and the q2m-SST relation significantly differs from what is expected using the Clausius-Clapeyron equation. This is interpreted in terms of an active ocean modifying the near-surface atmospheric state, driving convection, mixing and entrainment of air from the free troposphere into the MABL. The estimated values of the ocean-atmosphere coupling at the ocean small-scale are then used to develop a linear and SST-based downscaling method aiming to include and further investigate the impact of these fine-scale SST features into an available low-resolution latent heat flux (LHF) data set. The results show that they induce a significant increase of LHF (30% to 40% per °C of SST). We identify two mechanisms causing such a large increase of LHF: (1) the thermodynamic contribution that only includes the increase in LHF with larger SSTs associated with the Clausius-Clapeyron dependence of saturating water vapor pressure on SST and (2) the dynamical contribution related to the change in vertical stratification of the MABL as a consequence of SST anomalies. Using different downscaling setups, we conclude that largest contribution comes from the dynamic mode (28% against 5% for the thermodynamic mode). To validate our approach and results, we have implemented a set of high-resolution WRF numerical simulations forced by high-resolution satellite SST that we have analyzed in terms of LHF using the same algorithm. The LHF estimate biases are reduced by a factor of 2 when the downscaling is applied, providing confidence in our results.

Electric Field-Induced Water Condensation Visualized by Vapor-Phase Transmission Electron Microscopy.

Understanding the nanoscale water condensation dynamics in strong electric fields is important for improving the atmospheric modeling of cloud dynamics and emerging technologies utilizing electric fields for direct air moisture capture. Here, we use vapor-phase transmission electron microscopy (VPTEM) to directly image nanoscale condensation dynamics of sessile water droplets in electric fields. VPTEM imaging of saturated water vapor stimulated condensation of sessile water nanodroplets that grew to a size of ∼500 nm before evaporating over a time scale of a minute. Simulations showed that electron beam charging of the silicon nitride microfluidic channel windows generated electric fields of ∼108 V/m, which depressed the water vapor pressure and effected rapid nucleation of nanosized liquid water droplets. A mass balance model showed that droplet growth was consistent with electric field-induced condensation, while droplet evaporation was consistent with radiolysis-induced evaporation via conversion of water to hydrogen gas. The model quantified several electron beam-sample interactions and vapor transport properties, showed that electron beam heating was insignificant, and demonstrated that literature values significantly underestimated radiolytic hydrogen production and overestimated water vapor diffusivity. This work demonstrates a method for investigating water condensation in strong electric fields and under supersaturated conditions, which is relevant to vapor-liquid equilibrium in the troposphere. While this work identifies several electron beam-sample interactions that impact condensation dynamics, quantification of these phenomena here is expected to enable delineating these artifacts from the physics of interest and accounting for them when imaging more complex vapor-liquid equilibrium phenomena with VPTEM.

Consistency of Water Vapour Pressure and Specific Heat Capacity Values for Modelling Clay-Based Engineered Barriers

The aim of this study is to assess the consistency in the modelling of thermo-hydraulic problems in clay-based engineered barriers. This study focuses on two aspects: the modelling of vapour pressure as a function of temperature, and the specific heat capacities of liquid water and water vapour in relation to the enthalpy of vaporisation and the internal energy of liquid water and water vapour. Regarding the first aspect, several formulations of the saturated vapour pressure have been inspected, evaluating their accuracy and information provided in the temperature range from 0 to 150 °C. Regarding the second aspect, the enthalpy of vaporisation and the internal energy of water were used to assess the consistency of pairs of specific heat capacity values in the same temperature range. Values from the literature were also inspected. An accurate and simple enough expression for the saturated water vapour pressure with temperature has been identified as the optimal option for modelling. Recommendations on specific heat capacity constant values for liquid water and vapour are suggested to maximise consistency in the studied temperature range. However, the loss of accuracy in the enthalpy or internal energy of vaporisation associated with the inspected specific heat capacity pairs is limited.

Zmiany wilgotności powietrza w Łodzi w latach 1966–2020 w świetle wybranych wskaźników

The aim of the study is to present changes in air humidity in central Poland in the years 1966–2000 in Łódź as an example. The values of air temperature, relative humidity and atmospheric pressure from four observation terms, 00, 06, 12 and 18 UTC, were used. On this basis, the saturated vapour pressure, the current vapour pressure, and the saturation deficit were calculated. Then, the variability of these three indicators and relative humidity was examined. The variability of monthly and seasonal average values of humidity indices in four observation periods was presented, the trends in seasonal variability of humidity indices were calculated and the distribution functions of their distributions were compared in the midday period in three 15-year periods: 1966–1980, 1986–2000 and 2006–2020. It has been shown that the pressure of saturated water vapour is the highest in summer, the lowest in winter, and slightly higher in spring than in autumn at all times, except for the night. It increased significantly in the studied period as a result of the increase in air temperature. A comparison of the distributions in three 15-year periods shows a significant increase in the probability of occurrence of high values of saturation vapour pressure, even above 30hPa. The water vapour pressure in the air is highest in summer and lowest in winter, but in spring it is lower than in autumn. All trend coefficients are positive, but only less than half are statistically significant. A comparison of the distributions over three 15-year periods show a slight increase in the probability of higher values of the actual vapour pressure. The saturation deficit, as the difference between the previous two indicators, increases significantly. Its value in spring is significantly higher than in autumn. The trend is positive, especially in spring and summer, and the comparison of distributions shows that in the last 15 years the probability of high values of saturation deficit increased significantly. The course of relative humidity is the opposite of saturation deficit. In autumn, the relative humidity is definitely higher than in spring. The trend is down. To sum up, warming brings an increase in the capacity of the atmosphere for water vapour, a slight increase in the amount of water vapour in the air, but also a significant increase in saturation deficit and a decrease in relative humidity, which is particularly strong in spring in the first half of the growing season.

Laboratory Studies of Brine Growth Kinetics Relevant to Deliquescence on Mars

Although previous studies have shown that the near-surface environmental conditions on Mars may permit salt deliquescence and therefore brine production, there is significant uncertainty in the kinetics of the process. Indeed, experimental studies have shown that deliquescence is either very rapid or too slow to be relevant to Mars. To resolve this uncertainty, we performed laboratory experiments to investigate the growth rate of Mars-relevant calcium perchlorate brines over a range of temperatures (184–273 K) and water vapor pressures (0.2–220 Pa). We show that the brine growth is faster at higher water vapor pressures and lower temperatures and for smaller particles. From our data, we determined a temperature-dependent net uptake coefficient for gas phase water molecules colliding with a perchlorate brine surface in the range of 3.8 × 10−4 at 185 K to 4.2 × 10−6 at 273 K. These values suggest that deliquescence on Mars is likely to be slow even when conditions thermodynamically permit a brine to form. We find that along the Curiosity rover traverse at Gale Crater, the near-surface conditions would only allow particles <1 μm to fully deliquesce over a typical sol. At the higher-latitude Phoenix landing site, deliquescence may be 30% faster due to the higher water vapor pressures, but still, only micron-scale salt grains or coatings would be expected to deliquesce during a typical sol. These results suggest that brines formed via deliquescence on the surface of Mars are likely only present on small scales that may not be readily detected using conductivity or imaging techniques.

Fire resistance tests on polypropylene-fiber-reinforced prestressed concrete box bridge girders

This paper presents an experimental study on fire behavior of polypropylene fiber prestressed concrete (PFPC) bridge girders subjected to localized hydrocarbon-fuel fire (mixed diesel oil and natural gas) and applied structural loading. The thermal responses, including temperature inside chamber, temperature within concrete and prestressing strands, were measured and analyzed throughout entire fire exposure duration. Further, structural responses, embracing mid-span deflection, effective prestress, polypropylene (PP) fiber concrete spalling, fire resistance, damage evolution and failure modes, attained from test were investigated in detail. The experimental results show that PP fiber can significantly release pressure of water vapor generated within high-strength concrete used in PFPC bridge girders, thus effectively enhancing spalling resistance of concrete in PFPC girders at elevated temperatures. The diaphragm can keep temperature inside chamber and also within top flange of PFPC box bridge girders steady for a period of time when temperature reaches 100 °C. However, the diaphragm has little effect on structural response of PFPC box bridge girders. The mid-span deflection increases sharply at final stage of fire exposure. Meanwhile, fracture of prestressing strands occurs and the effective prestress decreases suddenly towards final stage of fire exposure. Thereafter, PFPC bridge girders rapidly get to limit state dependent on rate of deflection, thus exhibiting a brittle failure characteristic. This failure of PFPC bridge girders can be prevented using reserved prestressing strands. PFPC bridge girders, designed as per under-reinforced girder at room temperature, vulnerably present failure characteristics of rare-reinforced girder under fuel fire exposure conditions.

NaHCO3 as a carrier of CO2 and its enhancement effect on mineralization during hydrothermal alteration of basalt

Reaction of carbon dioxide (CO2) with minerals to generate stable carbonates, also known as CO2 mineralization, has been regarded as one of the most promising methods for safe and permanent carbon storage. As a promising feedstock, basaltic rock has gained special interest, and elevating basalt carbonation efficiency with the reduction of negative environmental impact is the main challenge for CO2 mineralization system development. Considering multiple potential positive effects of the CO2 carrier, NaHCO3, we conducted this study to experimentally evaluate the CO2 storage efficiency during water-basalt-NaHCO3 interactions under hydrothermal conditions at 200–300°C. The inclusion of NaHCO3 was confirmed to drastically promote the alteration of basalt, especially at higher temperatures. As revealed by experiments conducted at the saturated vapor pressure of water, the carbon storage efficiency at 300°C reached 75 g/kg of basalt in 5 days, which was 12 times higher than that at 200°C. In such hydrothermal systems, basalt was carbonated to generate calcite (CaCO3), where the Ca was mainly from plagioclase; Mg and Fe were incorporated into smectite, and Na in the saline system participated in the formation of Na silicates (i.e., analcime in the case of basalt). Due to the presence of additional Na in solution, all the released elements were consumed quickly with generation of secondary minerals in turn promoted basalt dissolution to release more Ca for CO2 storage. This study illuminated the role of NaHCO3 in basalt carbonation and provided technical backup to the design of advanced CO2 mineralization systems.

The Lagging Effect of Precipitation on NAIs Concentrations on Rainy Days in Wuyi Mountain National Park, China

Precipitation (PRE) is an essential factor that affects the negative air ions (NAIs) concentrations. However, the mechanism of NAIs concentrations and their influencing factors on rainy and non-rainy days remains unclear. Here, we used hourly data of NAIs concentrations and meteorological data in 2019 to analyze the distribution of NAIs concentrations and its influencing factors on rainy and non-rainy days in the Wuyi Mountain National Park (WMNP) of China, which was listed as a World Cultural and Natural Heritage Site in 1999. The results indicated that the NAIs concentrations on rainy days were significantly higher than on non-rainy days. However, the NAIs concentrations on rainy days were slightly higher than on the first and second days after rainy days. Then, the NAIs concentrations were significantly reduced on the third day and after that. Thus, rainy days lead to a 2-day lag in the smooth reduction of NAIs on non-rainy days after rainy days. NAIs concentrations were significantly correlated with the relative humidity (RHU) on both rainy and non-rainy days. By analyzing the meteorological factors on NAIs for ranking the feature importance scores on rainy and non-rainy days, PRE was ranked first on rainy days, and sea level pressure (PRS_Sea) and temperature (TEM) were ranked first and second on non-rainy days, respectively. Based on the univariate linear regression model (ULRM), NAIs concentrations responded strongly (higher absolute slope values) to RHU on rainy days and to pressure (PRS), visibility (VIS), water vapor pressure (VAP), TEM, and ground surface temperature (GST) on non-rainy days. The results highlight the importance of PRE in the lag time of NAIs concentrations on rainy and non-rainy days.