Guangzhou Institute of Geochemistry
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Exploitation and Utilization of Generated Oil and Gas by Pyrolysis Simulation Modeling of Shale Source Rocks under the Condition of In Situ Conversion
No full textPrevious studies have mainly focused on the source rocks of the 7th Member of Yanchang Formation (Chang 7 Member) in the Ordos Basin, with very few studies focusing on the extracts from the source rocks. These extracts have important guiding significance for studying the in situ conversion process of shale oil. Taking the shale source rock of the Chang 7 Member as an example, this paper selected the extract of shale source rock (i.e., retained oil), which has been less studied previously, as the sample to carry out the hydrocarbon-generating pyrolysis simulation experiment of a semi-open-semi-closed system. Seven groups of parallel simulation experiments were designed with a pressure of 20 MPa. The generated oil and gas were collected and quantified, and their geochemical characteristics were researched. In addition, the generated oil and gas were investigated from aspects of cumulative yield and net increased yield, and the chromatographic and mass spectral characteristics of the generated oil were also researched. Based on this, an inductive hydrocarbon generation model of retained oil in shale source rocks was established: slow hydrocarbon generation stage (300-320 degrees C), rapid hydrocarbon generation stage (320-360 degrees C), and residual oil pyrolysis stage (0.79%Ro-1.47%Ro). This study is of important significance to guide the research on the in situ conversion process of shale source rock
Preface to "atmospheric geochemistry: A special issue endorsed by IGAC China working group and IAGC China working group"
No full textToxicity and chemical characterization of shale gas wastewater discharged to the receiving water: Evidence from toxicity identification evaluation
No full textFlowback and produced water (FPW) generated from shale gas extraction is a complex mixture consisting of injected drilling fluid, deep formation water, and byproducts of downhole reactions. Limited knowledge is available regarding the impact of discharged FPW on surface water in China. With the development of shale gas exploitation, this emphasizes an urgent need for comprehensive assessments and stringent regulations to ensure the safe disposal of shale gas extraction-related wastewater. Herein, we explored potential impacts of treated shale gas wastewater discharged into a local river in southwest China through toxicity identification evaluation (TIE). Results revealed that organics and particulates significantly contributed to the overall toxicity of the treated FPW wastewater. Through target and suspect chemical analyses, various categories of organic contaminants were detected, including alkanes, aromatic hydrocarbons, biocides, phenols, and phthalates. Furthermore, non-target analysis uncovered the presence of surfactant-related contaminants in tissues of exposed organisms, but their contribution to the observed toxicity was unclear due to the lack of effect data for these compounds. Higher toxicity was found at the discharge point compared with upstream sites; however, the toxicity was rapidly mitigated due to dilution in the receiving river, posing little impact on downstream areas. Our study highlighted the importance of monitoring toxicity and water quality of FPW effluent even though dilution could be a viable approach when the water volume in the discharge was small
Reduced sulfur compounds and carboxylic acid groups in dissolved PFRs of iron-biochar enhance Cr(VI) reduction in anaerobic conditions
No full textIn addition to the adsorption and immobilization capacities of iron-modified biochars, these materials produce persistent free radicals (PFRs) that can carry out metal [i.e., Cr(VI)] redox transformations, but the primary forms and active species of PFRs involved are not well understood. Here, we investigated the key species of PFRs of alpha-Fe2O3-modified biochar (MBC) and their influence on Cr(VI) reduction under anaerobic conditions simulating paddy soil environments. MBC produced bulk phenoxyl PFRs that promoted Cr(VI) reduction due to the catalytic effect of the transition metal Fe. In addition, MBC was more efficient in reducing Cr(VI) under anaerobic conditions than under aerobic conditions due to the more active and accessible dissolved PFRs present in the dissolved organic matter (DOM). The electron transfer capacity of DOM was demonstrated by excitation-emission matrix (EEM) spectrophotometry combined with parallel factor analysis, which showed that the protein-like and humic-like components of DOM were involved in Cr(VI) reduction. Furthermore, Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) analysis indicated that reduced-S compounds (O/S < 4) and carboxylic acid (-COO) groups in the unsaturated aliphatic and lignin-like compounds are potentially the main active species accelerating Cr(VI) reduction under anaerobic conditions. Our results provide new insights into the role of dissolved PFRs from iron-modified biochar in promoting Cr(VI) reduction under anaerobic conditions such as flooded soils
Reduced sulfur compounds and carboxylic acid groups in dissolved PFRs of iron-biochar enhance Cr(VI) reduction in anaerobic conditions
No full textIn addition to the adsorption and immobilization capacities of iron-modified biochars, these materials produce persistent free radicals (PFRs) that can carry out metal [i.e., Cr(VI)] redox transformations, but the primary forms and active species of PFRs involved are not well understood. Here, we investigated the key species of PFRs of alpha-Fe2O3-modified biochar (MBC) and their influence on Cr(VI) reduction under anaerobic conditions simulating paddy soil environments. MBC produced bulk phenoxyl PFRs that promoted Cr(VI) reduction due to the catalytic effect of the transition metal Fe. In addition, MBC was more efficient in reducing Cr(VI) under anaerobic conditions than under aerobic conditions due to the more active and accessible dissolved PFRs present in the dissolved organic matter (DOM). The electron transfer capacity of DOM was demonstrated by excitation-emission matrix (EEM) spectrophotometry combined with parallel factor analysis, which showed that the protein-like and humic-like components of DOM were involved in Cr(VI) reduction. Furthermore, Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) analysis indicated that reduced-S compounds (O/S < 4) and carboxylic acid (-COO) groups in the unsaturated aliphatic and lignin-like compounds are potentially the main active species accelerating Cr(VI) reduction under anaerobic conditions. Our results provide new insights into the role of dissolved PFRs from iron-modified biochar in promoting Cr(VI) reduction under anaerobic conditions such as flooded soils
First report of Early Permian Tasmanite oil shales in northern Pangea with global implications
No full textDuring the Late Paleozoic Ice Age (LPIA; particularly early Permian), organic material of the alga Tasmanites was extensively deposited in sediments of southern Gondwana, which formed the Tasmanite oil shales that have only been identified in Tasmania, Australia. It remains unclear whether other analogous geological records exist worldwide that formed at the same time, and the origin is enigmatic. This paper reports the first discovery of Tasmanite oil shales in northern Pangea, specifically in the Lucaogou Formation of the Junggar Basin, China, deposited during the Artinskian (ca. 290 Ma). The organic petrological features of Tasmanites are clearly visible, including thick-walled disks with tubes and radially arranged channels. These shales have markedly elevated C28/C29 steranes and tricyclic terpanes/hopanes ratios. Based on inorganic geochemical data, the salinity of the paleo-lake during deposition of the Tasmanite oil shale interval decreased abruptly from saline to brackish-freshwater. In addition, the pH changed from alkaline to nearly neutral, while the redox environment changed from anoxic to suboxic. Enhanced continental chemical weathering and the change in salinity of the paleo-lake occurred at the same time as global warming and large-scale glacier melting during the Artinskian, which promoted the habitat of the low -salinity tolerant Tasmanites. Our results provide new geological evidence for another occurrence of early Permian Tasmanite oil shales, indicating that Tasmanites flourishs and the associated oil shales may have been widely deposited at the end of the LPIA. The flourishment of Tasmanites archives biotic-environmental co -evolution
Fluid-induced dissolution-reprecipitation of tungsten minerals in the Hongling deposit, South China
No full textTungsten is a critical metal that is predominantly found in magmatic-hydrothermal W-Sn deposits. However, the behavior and controlling factors of tungsten in highly evolved granitic systems are not yet well-known. In this study, we examined the integrated mineral textures and geochemistry of wolframite and scheelite from the Hongling tungsten deposit in the word-class Nanling W-Sn metallogenic belt, South China. Our results reveal that wolframite and scheelite from the muscovite granite of the highly evolved Reshui granite pluton can be classified into three generations formed through a process of coupled dissolution-reprecipitation. Wolframite with altered relict textures was formed during the early magmatic stage, while the two generations of scheelite (Sch-I and SchII) were formed during the magmatic-hydrothermal transitional stage. The formation of Sch-I, which exhibits a notable positive Eu anomaly, required the participation of external Ca-rich reduced fluids within the magmatic exsolved fluids from the highly evolved peraluminous pluton. The porous Sch-II occurs as marginal overgrowth or fracture-filling textures and exhibits a similar negative Eu anomaly as the dissolved wolframite. These three generations of tungsten minerals exhibit distinguishable REE contents and distribution patterns, with increasing LREE and decreasing HREE trends. The fluctuation of oxygen fugacity and the compositional evolution of tungsten minerals from wolframite through Sch-I to Sch-II indicate the involvement of external Ca-rich reduced fluids within the magmatic exsolved fluids from the highly evolved peraluminous pluton. The coupled dissolution of wolframite and the reprecipitation of scheelite were likely induced by intensive fluid-rock interactions, which are critical for the remobilization and enrichment of tungsten in magmatic-hydrothermal deposits. We inferred that such fluid-induced dissolution-reprecipitation of tungsten minerals provides new insights into the formation of the world-class Nanling W-Sn metallogenic belt in South China
Molybdenum isotopic fractionation in the Panzhihua mafic layered intrusion in the Emeishan large igneous province, southwest China
No full textThe large Mo isotopic fractionations between diferent geological reservoirs make this isotopic system a potentially useful tool for constraining the origins of magmatism. However, the efect of magmatic diferentiation on Mo isotopes is still controversial. In this study, we obtained Mo isotope data for the Panzhihua gabbroic intrusion (i.e., including mineral separates of clinopyroxene, plagioclase, magnetite, and ilmenite). The whole-rock samples and mineral separates exhibit large Mo isotopic fractionations with delta Mo-98/95 values as follows: magnetite (-0.73 parts per thousand to -0.32 parts per thousand ) < clinopyroxene (-0.32 parts per thousand to -0.10 parts per thousand ) < ilmenite (0.06 parts per thousand to 0.36 parts per thousand ) < plagioclase (0.33 parts per thousand to 0.83 parts per thousand ). Iron-Ti oxides have Mo contents that are one order of magnitude higher than those of clinopyroxene and plagioclase. Mass balance calculations based on Mo isotopes and contents are consistent with an accumulated origin for the Panzhihua intrusion. Rayleigh fractionation modeling shows that the removal of magnetite and ilmenite results in significant Mo isotopic fractionation in the residual magma. Due to the low Mo contents of clinopyroxene and plagioclase, Mo isotopes are not significantly fractionated by the removal of these minerals. Therefore, our study highlights that fractionation of Fe-Ti oxides can cause considerable Mo isotopic fractionation; consequently, caution is needed when using Mo isotopes to infer magma origins
Measurement report: Atmospheric ice nuclei in the Changbai Mountains (2623 m a.s.l.) in northeastern Asia
No full textAtmospheric ice nucleation plays an important role in modulating the global hydrological cycle and atmospheric radiation balance. To date, few comprehensive field observations of ice nuclei have been carried out at high-altitude sites, which are close to the height of mixed-phase cloud formation. In this study, we measured the concentration of ice-nucleating particles (INPs) in the immersion freezing mode at the summit of the Changbai Mountains (2623 m above sea level), northeast Asia, in summer 2021. The cumulative number concentration of INPs varied from 1.6 x 10(-3) to 78.3 L-1 over the temperature range of -5.5 to -29.0 degrees C. Proteinaceous-based biological materials accounted for the majority of INPs, with the proportion of biological INPs (bio-INPs) exceeding 67 % across the entire freezing-temperature range, with this proportion even exceeding 90 % above -13.0 degrees C. At freezing temperatures ranging from -11.0 to -8.0 degrees C, bio-INPs were found to significantly correlate with wind speed (r = 0.5-0.8, p 0.7, p < 0.05), with the valley breezes from southern mountainous regions also influencing the concentration of INPs. Moreover, the long-distance transport of air mass from the Japan Sea and South Korea significantly contributed to the high concentrations of bio-INPs. Our study emphasizes the important role of biological sources of INPs in the high-altitude atmosphere of northeastern Asia and the significant contribution of long-range transport to the INP concentrations in this region
Surface reconstructed Fe@C1000 for enhanced Fenton-like catalysis: Sustainable ciprofloxacin degradation and toxicity reduction
No full textThe Fe-based catalysts typically undergo severe problems such as deactivation and Fe sludge emission during the peroxymonosulfate (PMS) activation, which commonly leads to poor operation and secondary pollution. Herein, an S-doped Fe-based catalyst with a core-shell structure (Fe@C-T, T = 1000 degrees C) was synthesized, which can solve the above issues via the dynamic surface evolution during the reaction process. Specifically, the Fe-0 on the surface of Fe@C-1000 could be consumed rapidly, leaving numerous pores; the Fe3C from the core would subsequently migrate to the surface of Fe@C-1000, replenishing the consumed active Fe species. The X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyses demonstrated that the reaction surface reconstructed during the PMS activation, which involved the Fe-III in-situ reduction by S species as well as the depletion/replenishment of effective Fe species. The reconstructed Fe@C-1000 achieved near-zero Fe sludge emission (from 0.59 to 0.08-0.23 mg L-1) during 5 cycles and enabled the dynamic evolution of dominant reactive oxygen species (ROS) from SO4- to (FeO)-O-IV, sustainably improving the oxidation capacity (80.0-92.5% in following four cycles) to ciprofloxacin (CIP) and reducing the toxicity of its intermediates. Additionally, the reconstructed Fe@C-1000/PMS system exhibited robust resistance to complex water matrix. This study provides a theoretical guideline for exploring surface reconstruction on catalytic activity and broadens the application of Fe-based catalysts in the contaminants elimination