H2O Content Research Articles

Effects of VOC emission reduction on atmospheric photochemistry and ozone concentrations during high-ozone episodes

We studied atmospheric volatile organic compounds (VOCs) characteristics and sources during fifteen high ozone (O3) episodes (daily 1-h maximum >100 ppbv and maximum 8-h average > 80 ppbv) in Nanjing, China, and used a photochemical box model to study the O3 formation sensitivity of VOCs, O3 photochemistry, radical budget, and reactivity for different emission reduction scenarios together with the base case ones. Overall, emission reduction from biogenic sources, followed by combustion sources, multiple sources, and solvent usage, had the major impacts on the O3 concentrations. According to photochemical box model simulations, isoprene was the most sensitive or influential VOC in the formation of O3, followed by ethylene, o-xylene, and cis-2-pentene. A 20.6 ± 11.7% concentration reduction of the sixteen most sensitive VOCs (SV16) for the production of O3 could bring the O3 concentration below the national standard level (daily 1-h maximum <100 ppbv). Besides, a 30% emission reduction from all the anthropogenic sources was more than enough to bring the O3 concentration below the national standard level. The total emission reduction of alkenes was always enough to bring the O3 concentration below the national standard level, which was not the case for aromatics under severe pollution conditions. The simulated OH reactivity analysis illustrates the importance of alkenes and aromatics, which account for about half of the total OH reactivity. The highest OH reactivity decreased due to the emission reduction for biogenic sources, followed by combustion and multiple sources. Alkenes played a major role in the OH, HO2, and RO2 radical's formation in the study area. The biggest drop in OH, HO2, and RO2 radical concentrations was noticed for biogenic emission reduction, followed by combustion and multiple sources. Due to the emission reduction from VOC sources, the highest O3 formation rates decreased for biogenic sources, followed by combustion and multiple sources. The acquired information is valuable to the scientific community and policymakers for formulating and implementing O3 pollution control strategies.

Clorine Solubility in Silicate Melts: New Experiments and Thermodynamic Mixing Model

We present new experimental data on Cl solubility in model basalt melts of eutectic compositions diopside (Di)–albite (Ab) and Di–anorthite ± quartz (Qtz). The starting glasses were equilibrated with aqueous fluid H₂O-NaCl-CaCl₂ at 4 kbar in the temperature range 900–1200°C. The experiments show that the Cl solubility decreases with increasing NaCl in the fluid. Ca-Na partitioning between melts and fluid is weekly temperature dependent and resembles that of the plagioclase-fluid system. The new experimental data, along with the previously published results on the model granite melting in the presence of (Na, K)Cl brines (Aranovich et al., 2013) are used to calibrate an empirical thermodynamic model for the salt species (NaCl, KCl, CaCl₂) in silicate melt. Calculations show that Cl solubility in the haplogranite melt decreases with increasing K/Na ratio in the fluid (and, correspondingly, melt). At high pressure (10 kbar) Cl solubility in the granite increases with increasing H₂O content. Calculated phase diagram for a simple pseudo-ternary system Ab–H₂O–NaCl demonstrates complex phase relations and, correspondingly, evolution of the H₂O and NaCl concentrations in the melt. Literature data on the variations of H₂O and NaCl in the melt and fluid inclusions in Qtz from the granite of Badzhal tin deposit is used to illustrate complex evolution of a fluid-magmatic system.

Preparation and growth mechanism of nonpolar, semipolar and polar ZnO films: Correlation of preferred orientation, defects and optical properties

In the study, ZnO films with different preferred orientations were controllably prepared by using NH3·H2O to modulate the pH0 of chemical bath deposition. The samples were all characterised by field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), X-ray diffraction (XRD), ultraviolet-visible spectrophotometry (UV–VIS), X-ray photoemission spectroscopy (XPS) and photoluminescence (PL). The results show that ZnO films with polar, semipolar and nonpolar preferred orientations can be synthesised in a controlled manner by varying the pH0. Meanwhile, the influence of NH3·H2O concentration on the growth process of ZnO films is investigated in detail, and the relationship between the preferred orientation and optical properties is preliminarily discussed. At pH0= 7.32, the films exhibited semipolar (101) preferred orientation, the highest optical transmittance (89.15 %), and the highest concentration of Zni in the films. This study provides a method for the controlled synthesis of ZnO films with polar, semipolar and nonpolar preferred orientations and offers new possibilities for ZnO-based transparent semiconductor devices.

Characterization of OH species in kHz air/H2O atmospheric pressure dielectric barrier discharges

This work numerically studies densities and reaction mechanisms of OH species generated in atmospheric–pressure air dielectric barrier discharges with the model validated by experiments. The power consumption is measured, and the number of microdischarges (MDs) generated within a half period is captured by an intensified charge-coupled device (CCD) camera. The OH densities of cases with various H2O concentrations are measured using ultraviolet absorption spectroscopy. The numerical model integrating the 1.5D discharge fluid model and 3D background gas model (BGM) is adopted to predict the MD behavior and the generation of species related to OH generation. The simulated OH densities cover the range of 1.1 × 1019 and 1.6 × 1019 m−3 in the cases studied, agreeing with those measured. The simulated results show that most OH radicals are generated in MDs, while the reactive section contributes around 2% of the total OH generation. The detailed analysis shows that atomic oxygen (O(1D) and O) and O3 contribute most of the OH generation in the MDs. In contrast, the self-association reactions (i.e. 2OH + M → H2O2 + M and 2OH → O + H2O) and NO x species consume more than 64% of OH radicals generated in MDs. In the BGM, it is interesting to find that reactive species NO x play significant roles in both the OH generation and depletion in the reactive section. The distributions of species related to the OH species obtained by the BGM are presented to elucidate the detailed chemistry of OH species in the reactive section.

Elasticity of Single‐Crystal Clinohumite at High Pressures and Temperatures: Implication for the H2O and F Circulation in the Earth's Mantle

AbstractIn this study, we have determined the single‐crystal elasticity of clinohumite [Mg8.85Ti0.19Si3.93O16(OH1.11F0.89)] using Brillouin measurement up to 21 GPa at 300 K and 1 bar at 750 K, respectively. The elasticity of clinohumite was determined to be KS0 = 126.2(3) GPa, G0 = 79.7(2) GPa with pressure derivatives KS′ = 4.2(1), G′ = 1.3(1), pressure derivatives ∂KS/∂T = −0.024(1) GPa/K, and ∂G/∂T = −0.011(1) GPa/K). We comprehensively examined the effects of varying H2O, fluorine content and thermal states, on the velocity and density structures of the subducted harzburgite layer. Assuming a typical H2O content of 2 wt.% within harzburgite, our modeling has shown that hydrous harzburgite with clinohumite as the decomposition product of serpentine along a hot slab geotherm even has the VP and VS 0.4–0.8(6)% greater than it dry counterpart at 250–380 km depth. Yet in the top transition zone, the addition of H2O and F can effectively lower the sound velocities and density. The F‐bearing hydrous harzburgite has the VP and VS 1.1(5)–1.3(3)% lower than its dry counterpart, and only 0.6(5)% and 2.3(5)% greater than the pyrolitic mantle. Along cold slab geotherm, phase A will replace clinohumite as the dominant hydrous phase in the harzburgite, the VP and VS are 4.8(5)–5.3(3)% and 5.9(5)–6.0(3)% greater than the pyrolitic mantle in the upper mantle. In the top transition zone, the difference is approximately 3% in VP and 5% in VS. Our results provide crucial experimental evidence for future assessments of the seismic signals of subducted slabs with different hydrous minerals and thermal states.

Effectiveness of Ti-in-amphibole thermometry and performance of different thermometers across lower continental crust up to UHT metamorphism

Metabasites are important constituents of deep crustal sections and are the favored rock type for studying lower crustal amphibolite to granulite transitions. However, metapelites may develop a larger number of temperature-sensitive mineral assemblages and are particular useful when extreme ultrahigh temperature (UHT) conditions are envisaged. A recent calibration of the Ti-in-amphibole thermometer by Liao et al. (2021) was supposed to make thermometry on metabasites quick and easy to apply. However, their calibration is based on experiments which were not originally designed to investigate in detail the temperature dependence of Ti in amphibole. In addition, a possible effect of aTiO2 and/or pressure on the Ti content of amphibole was not fully taken into account. This resulted in a calibration uncertainty of ± 70 °C (2σ), much higher than that of other single-mineral thermometers. In this study we firstly test the newly calibrated Ti-in-amphibole thermometer across the mid to lower crustal section of the Ivrea–Verbano Zone (IVZ; NW Italy) and compare the performance of different thermometric techniques across the sequence. Ti-in-amphibole thermometry records increasing peak temperatures from amphibolite (600–700 °C), transition (750–800 °C) and granulite (850–950 °C) zones. Titanium content of amphibole may be modified by retrograde fluid influx returning temperatures c. 200–300 °C lower than in non-altered domains. The comparison reveals that Zr-in-rutile thermometer in pelitic granulites seems to be more prone to post-peak resetting than the Ti-in-amphibole thermometry in nearby mafic rocks. This behavior is also confirmed by amphibole analyses from other UHT localities, where the performance of Ti-in-amphibole thermometry is comparable with that of Al-in-orthopyroxene in pelitic granulites. However, Ti-in-amphibole temperatures are underestimated in rutile-bearing samples and this limitation is not solely restricted to rocks containing high H2O contents as previously thought. Derived constraints on the diffusivity of Ti through amphibole demonstrate the robustness of the Ti-in-amphibole thermometer to later thermal disturbances. However, ad-hoc experiments are still necessary to improve the accuracy and precision of calibration and to extend its applicability. This advance will make mafic granulites routine targets for studies devoted to understanding the regional extent of UHT metamorphism.

Contrasting mineralized and barren porphyries in the Zhongdian Arc, insights from biotite and apatite compositions and halogen fugacity.

Copper mineralization in the Pulang (PL) porphyry deposit, Langdu (LD) porphyry-skarn deposit and Songnuo (SN) porphyry prospect in northwestern Yunnan, China, is closely related to the emplacement of quartz monzonite porphyries. The chemical compositions of biotite and apatite from those porphyries were analyzed to calculate the halogen fugacity and to constrain mineralized and barren porphyries. Our data show that biotites from the PL deposit have higher MgO, SiO2, TiO2 and F contents than those from the LD deposit or SN prospect. Compared to those in the LD deposit and SN prospect, the Mg (atoms per formula unit (apfu)) and AlVI (apfu) value in biotite is greater, and the F content is greater and the SO3 and Ce2O3/Y2O3 ratio in apatite are lower in the PL deposit. Ti-biotite thermometry and apatite-biotite geothermometry show that the crystallization temperature of biotite from the PL deposit is higher than that from the SN prospect or LD deposit. The results suggest that oxygen fugacity, magmatic sulfur, and H2O contents cannot be used to efficiently distinguish the PL deposit from the LD deposit and SN prospect. However, the halogen chemistry of biotite from the PL deposit is distinctly different from that of the LD deposit or SN prospect according to the lower IV (F), indicating that mineralized quartz monzonite porphyries in the PL deposit formed during the late magmatic stage, which is in contrast to those in the LD deposit and SN prospect. The mineralized porphyries display a remarkable negative linear relationship (r = -0.96) with the log (f HF/f HCl) and log (f H2O/f HF) ratio, which can be used to distinguish the mineralized and barren porphyries. Compared with other typical porphyry Cu systems, there is a remarkable positive linear relationship between IV (Cl) and log (f H2O/f HCl). In addition, the linear slope and intercept for log (f H2O/f HCl) ratios and the IV (Cl) of biotite from the potassic and phyllic alteration zones are significantly greater than those from other porphyries.

Revisiting the fluid regime during anatexis of metasedimentary rocks: New constraints from an integrated approach on the Cenozoic Himalayan granites

Water plays a critical role in the formation of granitic magmas and continental crust, but distinguishing water-present and water-absent anatectic scenarios using the geochemistry of granites is controversial. In this study we use an integrated approach that combines whole-rock major and trace element geochemistry, Ti-in-zircon thermometry, phase equilibrium modeling and trace element modeling to study the water regime that produced the Miocene granites from the Malashan-Gyirong area in central Himalaya to solve this controversy. The Gyirong granites have relatively low CaO, Sr and Ba and high Rb and (87Sr/86Sr)i and the Malashan granites have relatively high CaO, Sr and Ba and low Rb and (87Sr/86Sr)i, and were classified as group A and group B granites, respectively. Following previous interpretation, group A and group B granites are consistent with the products of water-absent and water-present melting of metasedimentary rocks, respectively. Ti-in-zircon thermometry yielded maximum values of 761–796 °C for the Gyirong granites and 730–764 °C for the Malashan granites. Distinct variation trends in zircon trace element compositions indicate that these two groups of granites were not linked by crystallization differentiation. Using average compositions of Proterozoic pelite as starting materials, phase equilibrium modeling was carried out at a variety of P–T–H2O conditions typical of the Himalayan orogen, P = 5, 10 and 15 kbar, T = 600–800 °C, H2O = 0–10 wt%. Pelite can produce melts with coupled CaO–Na2O contents for both groups at 10 kbar. Specifically, constraints from compositions and temperatures require that the bulk H2O content is ca. 1–2 wt% for group A granites and > ca. 4 wt% for group B granites. Compared with the maximum structural water content of the pelite at 10 kbar (1.77 wt%), this study testifies that group A granites formed under water-absent conditions and group B granites under water-present melting conditions. Modeling shows that water-present melting can produce melts with high Sr–Ba and low Rb contents resembling group B granites, while water-absent melting can produce melts with low Sr–Ba and high Rb contents resembling group A granites. This study highlights that water can indeed cause differences in granite geochemistry but a comprehensive investigation is required to better determine the role of water during crustal anatexis.

The magma plumbing system of the potentially hazardous Laoguipo volcano in the Tengchong Volcanic Field, SW China

The Late Pleistocene-Holocene Laoguipo volcano in the Tengchong Volcanic Field (TVF), southwestern China, displays significant geochemical and geophysical anomalies characteristics. Here we present petrographic observations, mineral chemistry, bulk rock geochemistry, thermobarometry, and thermodynamic simulation to evaluate the crystallization conditions and pre-eruptive magmatic processes occurring within the magma plumbing system. This study reveals the existence of two magma reservoirs beneath the Laoguipo volcano. The deep magma reservoir is composed of basaltic trachyandesite (SiO2 = 54–57 wt%), which is located at 15–19 km depths with 1087–1160 °C, 1.5–2 wt% H2O content, oxygen fugacity of ΔNNO+1 (Ni-NiO buffer), melt viscosity of 101.7–102.6 Pa·s, and density of 2.5–2.6 g/cm3. The formation of the deep magma reservoir is attributed to the 31% mass fractional crystallization of primitive basalt in the TVF. The shallow magma reservoir is composed of trachyte (SiO2 = 63–64 wt%), which is located at 6–11 km depths with 780–825 °C, 5.9–6.5 wt% H2O content, oxygen fugacity of ΔNNO+1 (Ni–NiO buffer), melt viscosity of 103.9–104.8 Pa·s, and density of 2.2–2.3 g/cm3. The shallow magma reservoir formed after the basaltic trachyandesite had assimilated 19% mass of the upper crustal material and fractionated 41% mass of the crystals. This study suggests that the shallow trachyte magma reservoir is being heated by the ascending deep basaltic trachyandesite magma, resulting in crystal dissolution, remobilization of crystal mush, and magma convection, which may be the main factors responsible for the geochemical and geophysical anomalies characteristics. The Laoguipo volcano is forming a mature magma plumbing system, which is of significance for forecasting future volcanic eruptions.

Review on Mercury Control during Co-Firing Coal and Biomass under O2/CO2 Atmosphere

Combining biomass co-firing with oxy-fuel combustion is a promising Bioenergy with Carbon Capture and Storage (BECCS) technology. It has the potential to achieve a large-scale reduction in carbon emissions from traditional power plants, making it a powerful tool for addressing global climate change. However, mercury in the fuel can be released into the flue gas during combustion, posing a significant threat to the environment and human health. More importantly, mercury can also cause the fracture of metal equipment via amalgamation, which is a major risk for the system. Therefore, compared to conventional coal-fired power plants, the requirements for the mercury concentration in BECCS systems are much stricter. This article reviews the latest progress in mercury control under oxy-fuel biomass co-firing conditions, clarifies the impact of biomass co-firing on mercury species transformation, reveals the influence mechanisms of various flue gas components on elemental mercury oxidation under oxy-fuel combustion conditions, evaluates the advantages and disadvantages of various mercury removal methods, and finally provides an outlook for mercury control in BECCS systems. Research shows that after biomass co-firing, the concentrations of chlorine and alkali metals in the flue gas increase, which is beneficial for homogeneous and heterogeneous mercury oxidation. The changes in the particulate matter content could affect the transformation of gaseous mercury to particulate mercury. The high concentrations of CO2 and H2O in oxy-fuel flue gas inhibit mercury oxidation, while the effects of NOx and SO2 are dual-sided. Higher concentrations of fly ash in oxy-fuel flue gas are conducive to the removal of Hg0. Additionally, under oxy-fuel conditions, CO2 and metal ions such as Fe2+ can inhibit the re-emission of mercury in WFGD systems. The development of efficient adsorbents and catalysts is the key to achieving deep mercury removal. Fully utilizing the advantages of chlorine, alkali metals, and CO2 in oxy-fuel biomass co-firing flue gas will be the future focus of deep mercury removal from BECCS systems.

Atmospheric Oxidation Capacity Elevated during 2020 Spring Lockdown in Chengdu, China: Lessons for Future Secondary Pollution Control.

This study presents the measurement of photochemical precursors during the lockdown period from January 23, 2020, to March 14, 2020, in Chengdu in response to the coronavirus (COVID-19) pandemic. To derive the lockdown impact on air quality, the observations are compared to the equivalent periods in the last 2 years. An observation-based model is used to investigate the atmospheric oxidation capacity change during lockdown. OH, HO2, and RO2 concentrations are simulated, which are elevated by 42, 220, and 277%, respectively, during the lockdown period, mainly due to the reduction in nitrogen oxides (NOx). However, the radical turnover rates, i.e., OH oxidation rate L(OH) and local ozone production rate P(O3), which determine the secondary intermediates formation and O3 formation, only increase by 24 and 48%, respectively. Therefore, the oxidation capacity increases slightly during lockdown, which is partly attributed to unchanged alkene concentrations. During the lockdown, alkene ozonolysis seems to be a significant radical primary source due to the elevated O3 concentrations. This unique data set during the lockdown period highlights the importance of controlling alkene emission to mitigate secondary pollution formation in Chengdu and may also be applicable in other regions of China given an expected NOx reduction due to the rapid transformation to electrified fleets in the future.

Density functional theory study on the mechanism of water gas shift reaction catalyzed by molybdenum hexacarbonyl in aqueous solvent

The mechanism of the water gas shift reaction (WGSR) catalyzed by Mo(CO)6 in both gaseous and aqueous phases were analyzed using the density functional theory (DFT) method. This study indicates that aqueous phase slightly increased every energy barrier for each step along the reaction path. The turnover frequency (TOF) of the reaction was determined using the energy span model (ESM). The TOF value in the aqueous phase (2.48 × 10−16 s−1) is slightly lower than in the gas phase (6.08 × 10−16 s−1). Actually, the advantages of aqueous phase may be attributed to high solubility and concentration of H2O, CO, OH−. The study of temperature (300–900 K) on energy profile shows that the reaction rate of WGSR can be increased with the increase of temperature. This research filled the gap in understanding the mechanism for the WGSR in aqueous phase, provides a reasonable theoretical foundation for molybdenum-based catalysts development.

Thermodynamic and exergy assessment of a biomass oxy-fuel combustion with supercritical carbon dioxide cycle under various recycle flue gas conditions

The ongoing development of second-generation oxy-fuel combustion system with higher oxygen concentration have presented a potential pathway for efficient biomass utilization. It also signified the meticulous role of recycled flue gas in altering the combustion behaviour in the combustor. Accordingly, investigation into different recirculation modes focusing on recycle ratio, wet/dry conditions, and excess oxygen ratio are conducted with an indirect supercritical power cycle integrated biomass oxy-fuel combustion system. Energy and exergy analyses, as well as composition of flue gas produced are presented. Energy and exergy efficiencies increased with reducing recycle ratio, with respective highest efficiency of 31.33% and 44.37% obtained at excess oxygen ratio of 1.01 and recycle ratio of 0.5 under wet condition. Investigation of CO2 and H2O concentration in produced flue gas depicted a separated stage profile under dry recycle condition, different from the slight diverging profile observed under wet condition when the recycle ratio varied. Concentration of NOx and SOx increased with decreasing recycle ratio and are generally higher under dry condition. Selective exergy analyses of the proposed power cycle presented highest exergy loss in the combustor, followed by the air separation unit, heat exchanger, CO2 compression and purification unit, and turbine generator. Based on the obtained result, wet recycle flue gas enhanced the combustion performance in the combustor but slightly impaired the convective heat transfer in the heat exchanger. The performance of proposed biomass power cycle is optimized at low recycle ratio of 0.5 under wet recycle condition.

120 kHz mid-infrared TDLAS sensor for H2O concentration and temperature measurement in rotating detonation engine exhaust flows

Rotating detonation engines (RDEs) require advanced rapid combustion diagnostic techniques to better understand their complex detonation processes. A fast mid-infrared TDLAS sensor was proposed to simultaneously monitor H2O concentration and temperature at the outlet of an H2/air-fueled RDE annular combustor. An iterative parameter extraction method from transmitted laser intensity was proposed to extract the H2O concentration and temperature of the detonation waves. A measurement rate of 120 kHz enables high-speed and simultaneous quantification of detonation wave combustions. The results show that when RDE operates stably, the detonation frequency, average temperature, and average molar percentage of H2O concentration of the detonation waves are 4.631 kHz, 1572.8 K, and 0.335, respectively. The detonation frequency extracted from H2O concentration and temperature is highly consistent with that extracted from thermal radiation, and the relative frequency error is only 0.022 %. The time-resolved H2O concentration and temperature data measured by the sensor accurately capture the thermal dynamics of the transient detonation waves.

Magmatic–Hydrothermal Evolution at the Barren Wushan Pluton, Southeast China: Insight into Controls on Mineralization Potential

Abstract A-type granites typically exhibit enrichment and mineralization of critical metals such as molybdenum and tin, essential for emerging technologies. However, the key factors influencing their mineralization potential remain elusive. The scarcity of studies on barren systems impedes the understanding of this question. Here, a detailed melt and fluid inclusion study was conducted on the barren Wushan pluton to reconstruct its magmatic evolution and magmatic–hydrothermal transition and explore the factors controlling the metallogenic potential of Mo and Sn in A-type granites. The Wushan pluton displays apparent lithological zoning consisting of two major phases, i.e., medium-grained seriate to porphyritic alkali feldspar granite and fine-grained porphyritic granite. Miarolitic cavities are widely developed in each lithofacies. The silicate melt inclusions from two granitic phases are rhyolitic, with moderate F contents (0.06–0.53 wt %) and depleted H2O contents (2.0–3.5 wt %). Melt inclusions show a wide range of incompatible element contents, such as Cs (9–1977 μg/g) and Rb (268–2601 μg/g), suggesting that Wushan has undergone a high degree of magma evolution. Mo behaves incompatibly in the magmatic evolution, and its content is enriched with the increasing degree of fractional crystallization, but remains constant after the Cs content exceeds 50 μg/g. Rayleigh fractionation model suggests that a large amount of Mo is extracted from fluid exsolution, which restrains Mo from further enrichment. In contrast, Sn behaves as a mildly incompatible element during the entire magmatic evolution history. The contents of Sn increase slowly compared to the trend of Mo, and the maximum contents reach ~30 μg/g in the highly evolved melts. The separation and crystallization of Sn-bearing minerals such as biotite, magnetite, and titanite inhibit the enrichment of Sn. Intermediate-density (ID-type) fluid inclusions hosted in the miarolitic quartz, representing the initial fluid exsolving from magma, display high Mo but low Sn concentrations. Constrained from two assemblages of coexisting ID-type fluid and melt inclusions, the fluid/melt partition coefficients of metals are obtained, with DMo, fluid/melt at 16–19, while DSn, fluid/melt is only about 1. The comparison between Mo-mineralized and barren intrusions worldwide shows that the metal contents in melts and fluids are not fundamentally different. The mineralized intrusions are characterized by the lower melt viscosity and the development of apophyses, both of which facilitate the extraction of metals and fluids from large magma chambers, followed by their concentration into a small rock volume. Consequently, it appears that physical and structural conditions rather than chemical compositions play a crucial role in the Mo mineralization process. Enrichment of Sn in melts is necessary but not decisive for Sn mineralization, whereas Sn enrichment in the initial exsolving fluid determines the Sn mineralization potential of a given granitic system. Compared to Sn enrichment in source melting and fractional crystallization which commonly enhance final Sn fertility in the highly evolved melts, the efficiency of Sn partitioning between melt and fluid plays a fundamental role in converting melt fertility into Sn-enriched fluids and thereby high mineralization potential of the magmatic–hydrothermal system. Our findings suggest a prospect for Mo exploration in the coastal A-type granite belt in South China, while the potential for Sn mineralization is expected to be limited.

Gasification study of Meulaboh coal under limited synthetic air and carbon dioxide environments

Gasification characteristics of Meulaboh coal have been investigated using chemical, petrographical, and thermogravimetry–mass spectrometry (TG-MS) approaches. The coal is classified as sub-bituminous C and dominated by huminite maceral (77% vol.). Based on proximate analysis, the coal comprises 12.56% moisture, 17.36% ash, 38.92% volatile matter, and 31.16% fixed carbon (adb). The coal is low in rank and dominated by reactive maceral. Thus, it is suitable for gasification study. TG-MS measurement revealed that the main pyrolysis product consists of H2O, CO2, and CH4, which generated significantly in slow and fast pyrolysis stages (180-294°C and 194-529°C, respectively). Gasification was performed using limited synthetic air and CO2 environments. TG and DTG thermograms show that gasification using CO2 resulted a higher mass loss rate than that using limited synthetic air. Moreover, gasification in a limited air atmosphere produced higher contents of H2O and CO2, while gasification in a CO2 atmosphere produced primarily CO.

Characteristics and classification of the peat at Toba Highland, North Sumatera, Indonesia

Peatland serves as a crucial natural resource with hydrological and other environmental functions essential for all living organisms. In some regions, peat soil isn't limited to lowland areas, it is also found in highland areas. This study is a survey research aiming to examine the characteristics of the highland peatlands of Toba North Sumatera, namely in the Village of Matiti II, Humbang Hasundutan Regency, North Sumatera and lowland peatlands as control of peatlands in general in Sidomulyo Village, Bilah Hilir Subdistrict, Labuhan Batu. The study employed a survey research approach with a descriptive method to determine the differences in the characteristics of highland Toba peat soils. In each area, a representative profile was made, and the soil morphology, characteristics and classification were observed according to the 2014 soil taxonomic classification. Soil samples were taken from each layer in the soil profile for soil analysis in the laboratory. Soil analysis included bulk density, pH H₂O, pH NaF, CEC, base saturation, organic C, total N, C/N, electrical conductivity (EC) and ash content. The results showed that the difference in altitude directly affected the microclimate and the hydrologic conditions, which in turn affected the characteristics of the peat soil. In the context of the Toba highland, the main source of peat soils comes from rainfall. In contrast with the peatland of the lowlands, where the impact of tides is a significant factor, the peat of the Toba highland is affected by the surrounding hills.

Effect of gas components on the post-discharge temporal behavior of OH and O of a non-equilibrium atmospheric pressure plasma driven by nanosecond voltage pulses

OH radicals and O atoms are two of the most important reactive species of non-equilibrium atmospheric pressure plasma (NAPP), which plays an important role in applications such as plasma medicine. However, experimental studies on how the gas content affects the post-discharge temporal evolutions of OH and O in the noble gas ns-NAPP are very limited. In this work, the effect of the percentages of O2, N2, and H2O on the amounts of OH and O productions and their post-discharge temporal behaviors in ns-NAPP is investigated by laser-induced fluorescence (LIF) method. The results show that the productions of OH and O increase and then decrease with the increase of O2 percentage. Both OH and O densities reach their maximum when about 0.8% O2 is added. Further increase of the O2 concentration results in a decrease of the initial densities of both OH and O, and leads to their faster decay. The increase of N2 percentage also results in the increase and then decrease of the OH and O densities, but the change is smaller. Furthermore, when the H2O concentration is increased from 100 to 3000 ppm, the initial OH density increases slightly, but the OH density decays much faster, while the initial density of O decreases with the increase of the H2O concentration. After analysis, it is found that OH and O are mainly produced through electron collisional dissociation. O(1D) is critical for OH generation. O3 accelerates the consumption processes of OH and O at high O2 percentage. The addition of H2O in the NAPP considerably enhances the electronegativity, while it decreases the overall plasma reactivity, accelerates the decay of OH, and reduces the O atom density.

A TGA-FTIR study on the pyrolysis of oil-based drilling cuttings and the influence of its solids on pyrolysis characteristics

During the drilling process in oil and gas fields, rock cuttings and other solid impurities are returned to the wellhead along with oil-based drilling fluids, forming oil-based drill cuttings. Organic pollutants in oil-based drill cuttings can be removed through pyrolysis. Although there has been some research on the pyrolysis of oil-based drilling cuttings, there is little analysis of the impact of rock-solid impurities in oil-based drill cuttings on the pyrolysis of organic components. Therefore, in this study, thermogravimetry coupled with infrared spectroscopy was used to analyze the pyrolysis characteristics of oil-based drill cuttings, exploring the major volatile components at different pyrolysis temperatures. Meanwhile, the oil and solids in oil-based drilling cuttings were separated by Soxhlet extraction, and the influence of solids on pyrolysis characteristics was studied. The results showed that the average pyrolysis activation energy and pre-exponential factor of the main pyrolysis stage of oil-based drill cuttings obtained by the FWO method were 50.6 KJ/mol and 3.951×104 s−1, respectively, while those of the separated residual oil were 84.7 KJ/mol and 2.905×109 s−1, respectively. This indicates that solids in oil-based drilling cuttings is increasing the mass loss rate during pyrolysis. The difference in pyrolysis kinetics between oil-based drilling cuttings and residual oil indicates that the solid in oil-based rock cuttings provides a surface for the reaction, which provides a reaction site for the decomposition of hydrocarbons to produce lighter volatile hydrocarbons. Additionally, the results of infrared spectroscopy indicated that the volatile products of the pyrolysis of oil-based drilling cuttings include CH4, CO, CO2, H2O, aldehydes, organic acids, etc. CH4 is the main product of the first weight loss stage, mainly released between 150°C and 200°C. With the increase in temperature, the concentrations of H2O, CO2, aldehydes, and organic acids gradually increased. At 600°C, the maximum concentration of CO2 release occurred, and the release of CO2 was the main reason for the third-stage weight loss in the pyrolysis of oil-based drilling cuttings

The Olivine-Spinel-aSiO2melt (OSaS) Oxybarometer: A New Method for Evaluating Magmatic Oxygen Fugacity in Olivine-Phyric Basalts

Abstract The compositions of cotectic olivine-spinel pairs in mafic magmas provide information on the oxygen fugacity of their host liquid, which can be accessed with a thermodynamic analysis of the olivine-spinel-liquid peritectic reaction: 3 F e 2 S i O 4 o l i v + O 2 s y s = 2 F e 3 O 4 s p + 3 S i O 2 m e l t The extraction of redox information from cotectic olivine-spinel pairs requires a well-defined silica activity value (aSiO2melt) for the melt of interest, as well as a method to calculate aFe2SiO4oliv and aFe3O4sp from chemical analyses of olivine and spinel, respectively. In this work, we develop a new olivine-spinel-aSiO2melt (OSaS) oxygen barometer that utilizes MELTS to obtain values of aSiO2melt, which are used with values aFe2SiO4oliv and aFe3O4sp determined from established solution models for olivine and spinel. We find that two implementations of the spinel-liquid peritectic equilibria can successfully generate magmatic oxygen fugacity values, (1) using a combination of mineral activity models from the literature (classical-OSaS) and aSiO2melt determined from MELTS, and (2) directly from chemical potentials obtained from MELTS, where a correction is added to the MELTS-derived chemical potentials for the magnetite component of the spinel (MELTS-OSaS). The two implementations of the OSaS were tested by using each model to recover the experimentally reported fO2 values for a dataset consisting of 50 olivine-spinel-glass assemblages derived from 14 published experimental studies. This dataset was filtered to remove potential disequilibrium phase assemblages, experiments with failed redox buffers, and poor-quality EMP analyses. Data quality metrics for the dataset filtration included Fe-Mg partitioning between olivine and melt, Fe-Mg partitioning between olivine-spinel, and an examination of whether aSiO2melt values were consistent with the reported phase assemblages. The classical-OSaS implementations reproduced the fO2 values reported from the experimental dataset with a standard error estimate (SEE) of ±0.39, root mean standard error (RMSE) of ±0.40 and average deviation of ±0.31. In testing the MELTS-OSaS model, we identified that the solution model for magnetite underpredicted the values of aFe3O4sp; therefore, we used the 50 experiments to assign a correction to the MELTS-predicted chemical potentials of magnetite. We tested 35 the MELTS-OSaS model with the magnetite correction on a dataset of 18 additional buffered experiments, filtered for redox equilibrium and not included in the original experimental dataset. We find that the MELTs-OSaS model, which includes the correction for the magnetite chemical potential, reproduces fO2 values for the 18 experiments with an SEE of ±0.20, root mean standard error (RMSE) of ±0.23 and average deviation of ±0.18. The OSaS oxybarometer can return magmatic fO2 values with a standard error of ± 0.20 to 0.39 log units, depending on the model selected, provided that the olivine-spinel cotectic temperature is known to an accuracy of ±25°C, the H2O content of the melt can be estimated within ±1.5wt%, and that the crystallization pressure of the olivine-spinel pair is &amp;lt; 500 MPa. We also propose that the OSaS models can be applied to experimental run products to determine or confirm oxygen fugacity values. We additionally suggest that the careful application of the OSaS oxybarometer can provide a reliable and robust alternative for performing redox studies on samples that do not contain sufficient glassy material to support the application of spectroscopic techniques (i.e., XANES and Mössbauer).