MARINE AND PETROLEUM GEOLOGY
·
2019
·
IF 3.538
Peng Liu,Xiaofeng Wang,Ying Lin,Changjie Liu,Xiaofu Li,Wenhui Liu
Adsorption and desorption processes of shale gas possess particular characteristics compared to conventional natural gas. Previous studies conducted desorption experiments on fresh core samples to investigate the isotope and chemical fractionations during the desorption process. However, complete chemical and isotope fractionations cannot be obtained due to the loss of gases during the coring process. In this study, we utilized a modified experimental apparatus based on the fixed adsorption bed to conduct systematic desorption experiments in confined systems with different proportions of free and adsorbed gases. The results show that different adsorption capacities and non-synchronous desorption for alkane gas components are leading factors influencing chemical fractionation during the desorption process. Meanwhile, C 1 /C 2 and C 1 /(C 1 +C 2 ) vary with different proportions of adsorbed gases in the same adsorption matrix. Generally, isotope fractionation between the adsorbed and free phases during desorption follows the Rayleigh fractionation model. The linear correlations between proportions of adsorbed CH 4 and isotope fractionation factors can be applied to predict the proportions of adsorbed gases. Calculations show that on average 55% of hydrocarbon gases exist at adsorbed state in shale gas from Yanchang Formation of Ordos Basin.
研究领域:
地质学
·
地球化学
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DOI
高影响因子
ANALYTICAL CHEMISTRY
·
2023
·
IF 7.4
Hongqian Yin,Heng Yao,Wei Yuan,Che-Jen Lin,Xuewu Fu,Runsheng Yin,Bo Meng,Jun Luo,Xinbin Feng
Measuring the isotopic composition of Hg in natural waters is challenging due to the ultratrace level of aqueous Hg (ng L–1). At least 5 ng of Hg mass is required for Hg isotopic analysis. Given the low Hg concentration in natural waters, a large volume of water (>10 L) is typically needed. The conventional grab sampling method is time-consuming, laborious, and prone to contamination during transportation and preconcentration steps. In this study, a DGT (diffusive gradients in thin films) method based on aminopropyl and mercaptopropyl bi-functionalized SBA-15 nanoparticles was developed and extended to determine the concentration and isotopic composition of aqueous Hg for the first time. The results of laboratory analysis showed that Hg adsorption by DGT induces ∼ −0.2‰ mass-dependent fractionation (MDF) and little mass-independent fractionation (MIF). The magnitude of MDF exhibits a dependence on the diffusion-layer thickness of DGT. Since Hg-MDF can occur in a broad range of environmental processes, monitoring the δ202Hg of aqueous Hg using the DGT method should be performed with caution. Field results show consistent MIF signatures (Δ199Hg) between the DGT and conventional grab sampling method. The developed DGT method serves as a passive sampling method that effectively characterizes the MIF of Hg in waters to understand the biogeochemical cycle of Hg at contaminated sites.
研究领域:
环境科学
·
分析化学
✓ 已验证
DOI
PubMed
高影响因子
GEOCHIMICA ET COSMOCHIMICA ACTA
·
2023
·
IF 5
Ziyan Han,Hejiu Hui,Haizhen Wei,Weiqiang Li
The Moon is depleted in volatile elements and compounds, and lunar samples exhibit a wide range of Cl isotopic compositions , which is believed to result from the volatilization of metal chlorides (e.g., NaCl, KCl, and FeCl 2 ). However, the Cl isotopic fractionation behavior during volatilization is not well constrained, particularly for metal chlorides. Furthermore, the effect of metal chloride evaporation on metal isotopes is poorly known. In the present study, we performed NaCl and KCl sublimation experiments to study Cl and K isotopic fractionations at temperatures ranging from 923 K to 1061 K and at pressures of 7×10 –5 bar to 1 bar in an N 2 atmosphere. The isotope fractionation factors of 37/35 Cl( α gas–solid ) from NaCl sublimation experiments are 0.9985±0.0002, 0.9958±0.0004, and 0.99807±0.00004 at 1, 10 –2 , and 7×10 –5 bar, respectively. Those of 41/39 K( α gas–solid ) and 37/35 Cl( α gas–solid ) from KCl sublimation experiments are 0.99884±0.00004 and 0.9988±0.0003 at 1 bar, 0.9977±0.0002 and 0.9972±0.0003 at 10 –2 bar, and 0.9989±0.0002 and 0.9989±0.0001 at 7×10 –5 bar, respectively. Chlorine and K isotopes fractionate more at 10 –2 bar than at 7×10 –5 bar and 1 bar. The saturation index in all the sublimation experiments was >95%, which resulted in near-equilibrium isotopic fractionation at the sublimation interface. Therefore, the isotopic fractionation was controlled by mass transfer processes in the gas and solid phases. The isotopic fractionation at 10 –2 bar was controlled by the chemical diffusion of sublimated gas in an N 2 atmosphere with almost no convection effect, (i.e., Pe number close to zero), whereas the isotopic fractionation at 1 bar was suppressed by atmospheric convection with a turbulence factor of 0.4±0.1 (i.e., Pe number >1). The extremely high sublimation rate and the very slow diffusion in the sublimating solid at 7×10 –5 bar suppressed isotopic fractionations. Based on our experimental results, calculations using Cl/K and Na/K in lunar materials reveal that degassing of KCl contributed very little (<0.2‰) to the K isotopic fractionation (>0.58‰) during lunar magma ocean degassing. The Cl isotopic fractionation factor from lunar samples is similar to our results at 10 –2 bar. This similarity of Cl isotope fractionation indicates that there may have been a transient atmosphere above the lunar magma ocean.
研究领域:
地球化学
·
行星科学
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产品关联
DOI
高影响因子
Communications Earth & Environment
·
2022
·Vol. 3
·期 1
·1-10
·
IF 7.29
Li Dongdong,Zhao Yu-Yan Sara,Meslin Pierre-Yves,Vals Margaux,Forget François,Wu Zhongchen
The high perchlorate (ClO 4 − ) to chloride (Cl − ) ratios observed at the Phoenix landing site, northern polar region of Mars, have been puzzling since detection. However, a lack of understanding of perchlorate-chloride-water systems under cryogenic conditions makes it difficult to assess ClO 4 − /Cl − ratios during deliquescence-related processes. Here we quantitatively evaluate ClO 4 − /Cl − fractionation in deliquescence-induced brines of magnesium- and calcium-perchlorate-chloride salt mixtures under subzero conditions, by measuring solubility data and constructing temperature-dependent thermodynamic models. We find that under specific relative humidity (RH) and temperature ( T ) conditions, deliquescence of perchlorate-chloride mixtures may form brines with fractionated ClO 4 − /Cl − signatures. Appropriate RH -T , water-limited conditions, and aeolian processes are required to produce and preserve the elevated ClO 4 − /Cl − signatures in soils. Under the present climate, the north polar region can support ClO 4 − /Cl − fractionation and potentially enrich perchlorate for longer periods on global Mars. This highlights the uniqueness of Mars’ arctic environment and its implications for modern habitability.
研究领域:
地球科学
·
化学
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DOI
高影响因子
ENVIRONMENTAL GEOCHEMISTRY AND HEALTH
·
2020
·Vol. 43
·期 3
·1225-1238
·
IF 3.472
Zhang Yanan,Gan Yiqun,Yu Kai,Han Li
Natural dissolved organic matter (DOM) in groundwater plays a crucial role in mobilizing arsenic (As). The complex contribution of DOM sources makes it hard to predict how the variation of environmental conditions would affect the distribution of As concentrations. Identifying the carbon isotope fractionation of DOM is the key to quantify DOM sources based on stable carbon isotopes. To understand the magnitude and variability in the carbon isotopic fractionation of DOM in competitive adsorption with As(V), this study investigated the δ 13 C values of fulvic acid (FA) and DOM during adsorption to goethite in the presence of As(V), at a specific pH and temperature. The carbon isotopic enrichment factor ( ε ) of FA in the adsorption to goethite was 0.65 ± 2.11‰ at pH 4.1, 25 °C, suggesting that FA molecules containing 13 C were more easily adsorbed to goethite. An increasing temperature increased ε FA from 0.32 ± 1.17‰ to 0.82 ± 5.39‰ at 15–35 °C. For dissolved sediment organic matter (DSOM) cases, molecules containing 13 C were more easily adsorbed to goethite. However, enrichment factors were not detected due to a reduction in DSOM adsorption and the diversity of natural humic substances or groups. The findings provide basic data for accurately ascertaining DOM sources through carbon isotopes, which is significant for predicting As fluctuation in aquifers affected by monsoon climate and/or human activities.
研究领域:
环境科学
·
地球化学
✓ 已验证
DOI
PubMed
高影响因子
INDUSTRIAL CROPS AND PRODUCTS
·
2021
·
IF 5.645
Xiuhong Zhong,Ran Yuan,Baoshuai Zhang,Bin Wang,Yaqi Chu,Zhaojiang Wang
Corn stover is collectable byproduct of grain production in agriculture. In this work, pith and leaf containing corn stover was fractionated into cellulose fibers, sugars, and lignin with remarkable yields of 38.9 %, 5.2 % and 25.4 %, respectively by one-step treatment using 85.0 % aqueous formic acid (FA) at conditions of 130 °C for 30 min. Paper sheet was prepared using the obtained cellulose fibers and showed excellent physical strength in terms of tensile index of 50.1 N·m/g, burst index of 3.0 kPa·m 2 /g and tear index of 6.1 mN·m 2 /g, comparable to the paper sheet made of conventional alkaline pulp. The obtained sugars contain 61 % of xylose, 17 % of glucose, 15 % of arabinose, 6 % of galactose and 1 % of mannose. The obtained water-insoluble lignin showed less aliphatic hydroxy groups by 37.9 %–46.6% than conventional technical lignins. This property is helpful to the lignin valorization in biodegradable polymer industry as interface-compatible fillers.
研究领域:
生物化学
·
材料科学
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DOI
高影响因子
ORGANIC GEOCHEMISTRY
·
2024
·
IF 2.6
Wenna Liu,Wanglu Jia,Qiang Wang,Jian Chen,Jinbu Li,Ping’an Peng
The isotopic fractionation of organic compounds during evaporation is one of the most critical issues in the field of stable isotopes. The hydrogen (H) isotopic compositions of light hydrocarbons (LHs) in oil have gained increasing interest in the research of oil genesis in recent years. However, compared to carbon (C) isotopes, our understanding of H isotopic fractionation patterns and influences for various types of LHs during evaporation is limited. In this study, we performed evaporation experiments at a constant temperature on LHs in three systems: single compound, alkane mixture, and light oil. We assessed the contents and H isotopic compositions of individual LHs in the residual liquid phase. The degree of H isotopic fractionation and influencing factors are studied combined with C isotopes. The H isotopic fractionation of LHs exhibits “inverse isotope fractionation” characteristics (a depletion in D in the residual LHs) with progressive evaporation, which is opposite to the C isotopic fractionation. The degree of isotopic fractionation is influenced by the evaporation system, the compounds’ molecular weight, and their structure. (1) The isotopic fractionation degree of H and C decreases in the following order: light oil > alkane mixture > single compound system. This difference may be related to the unsaturation level of the evaporative system and the evaporation matrix. (2) For LHs with the similar structure in the same evaporation system, the degree of H isotopic fractionation increases with increasing molecular weight due to the buffering effect of the sample pool, while the magnitude of C isotopic fractionation decreases. (3) For LHs with the same C number, methylcyclohexane (MCH) has a lower evaporation rate and less isotopic fractionation than the other C 7 compounds like 3-methylhexane (3-MH), n -heptane ( n C 7 ), and toluene (Tol). The distinctive fractionation characteristics of H isotopes make them very useful in geological applications. Combining H and C isotopic compositions of the same compound with the commonly used molecular ratios of LHs (e.g., n C 7 /MCH, Tol/ n C 7 ) enables full differentiation of three critical processes controlling oil formation: evaporation, thermal maturation, and biodegradation. Furthermore, the differences in H isotopic compositions between C 7 LHs (3-MH, n C 7 , and Tol) may be changed by evaporation, but the variation range is much smaller than that caused by source differences. Therefore, combining H and C isotopes may have great potential for oil source characterizations.
研究领域:
地球化学
·
石油地质学
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产品关联
DOI
高影响因子
ACS Catalysis
·
2024
·
IF 11.3
Yuting Zhu,Ning Li,Huifang Liu,Cheng Cai,Yehong Wang,Junju Mu,Feng Wang
Oxidative catalytic fractionation (OCF) represents an efficient approach to valorize lignocellulose for coproduction of monophenols and cellulose. To achieve an adequate monophenol yield, lignin oxidation, typically, requires high O2 pressure and an excess of Cu catalysts (the Cu dosage is approximately 3–5 mol equiv relative to the aromatic units in lignin). However, these conditions are relatively harsh for cellulose, resulting in severe decomposition to aliphatic acids. To address the trade-off between the monophenol yield and cellulose production, we develop an enhanced OCF using a CuMnCeO2 solid solution as the catalyst. Under relatively mild conditions (specifically, 0.1 MPa O2), 28.7 wt % monophenols were released from birch, using catalytic amounts of Cu (the Cu dosage was about 0.03 mol equiv relative to the aromatic units in lignin). Meanwhile, up to 83.9% of cellulose was collected as a solid pulp. The synergistic effect between doped metals (Cu and Mn) and oxygen vacancies was found to be crucial for enhanced lignin oxidation under mild conditions with minimized cellulose loss. The abundant surface oxygen vacancies facilitated oxygen activation by well-dispersed Cu and Mn species, while the strong interaction between these metals enhanced the catalyst’s reducibility. Key intermediates such as β-vinyl aryl ethers and byproduct glycolic acid were identified by model experiments, confirming that lignin oxidation primarily followed a 1,2-dioxetane homolysis mechanism. Overall, this enhanced OCF demonstrates the potential viability of lignin oxidation in practical biorefinery applications.
研究领域:
化学工程
·
生物质能
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
Engineering
·
2025
·
IF 11.6
Wenyue Yan,Baogang Zhang,Yi’na Li,Jianping Lu,Yangmei Fei,Shungui Zhou,Hailiang Dong,Fang Huang
Microbial vanadate (V(V)) reduction is a key process for environmental geochemistry and detoxification of vanadium (V). However, the electron transfer pathways and V isotope fractionation involved in this process are not yet fully understood. In this study, the V(V) reduction mechanisms with concomitant V isotope fractionation by the gram-positive bacterium Bacillus subtilis ( B. subtilis ) and the gram-negative bacterium Thauera humireducens ( T. humireducens ) were investigated. Both strains could effectively reduce V(V), and (90.5% ± 1.6%) and (93.0% ± 1.8%) of V(V) at an initial concentration of 50 mg·L −1 was removed over 10 d incubation, respectively. V(V) was bioreduced to insoluble vanadium (IV), which was distributed both inside and outside the cells. Electron transfer via cytochrome C, nicotinamide adenine dinucleotide, and glutathione played critical roles in V(V) reduction. Metabolomic analysis showed that differentially enriched metabolites (quinone, biotin, and riboflavin) mediated electron transfer in both strains. The aqueous V in the remaining solution became isotopically heavier as V(V) bioreduction proceeded. The obtained V isotope composition dynamics followed a Rayleigh fractionation model, and the isotope enrichment factor ( ε ) was (–0.54‰ ± 0.04‰) for B. subtilis and (–0.32‰ ± 0.03‰) for T. humireducens , with an insignificant difference. This study provides molecular insights into electron transfer for V(V) bioreduction and reveals V isotope fractionation during this bioprocess, which is helpful for understanding V biogeochemistry and developing novel strategies for V remediation.
研究领域:
环境微生物学
·
地球化学
·
生物化学
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DOI
高影响因子
SCIENCE OF THE TOTAL ENVIRONMENT
·
2024
·
IF 8.2
Yinhua Zhong,Yue Cheng,Huiying Zhang,Ran Wei,Jinzhi Ni,Weifeng Chen,Hui Jia
Biomass burning (e.g., wildfire) frequently occurs globally, inevitably produces abundant biomass-burning smoke-derived dissolved organic matters (BBS-DOMs) which eventually deposits on the surface environment. The adsorption and fractionation of BBS-DOMs on clays inevitably alter their biogeochemical process and environmental behaviors in the surface environment. It is therefore important to clarify the adsorption and fractionation of BBS-DOM on clay surfaces. This study found that the fractionation of BBS-DOMs on clays (montmorillonite and kaolinite) were controlled by their functional groups, aromaticity, molecular size and organic components. The spectral indexes (SUVA 254 and S 275 – 295 ) of BBS-DOMs in solution after clays adsorption suggested that with the increasing DOC concentration, the primary interaction between BBS-DOMs and clays changed from hydrogen bond to hydrophobic/pore filling effects, and the adsorption ratio of the large molecules increased, which were very different from natural fulvic acid . Furthermore, various BBS-DOMs and fulvic acid had different component fractionation behaviors during clay adsorption, because they had different abundances of protein-like matters (hydrogen bond donors), pyridine-N/pyrimidine-N (positive charge doners of electrostatic interaction), and fulvic-like matters (hydrophobic interaction and pore filling effect). Additionally, the increasing pH weakened the adsorption of bulk BBS-DOMs and enhanced the adsorption ratio of aromatic matters and smaller BBS-DOM molecules. Meanwhile, at a higher pH, the adsorption ratio of protein-like matters increased, while the adsorption ratio of humic- and fulvic-like matters decreased. The result was ascribed to the enhanced hydrogen bond between protein-like matters and clays as well as the enhanced electrostatic repulsion between humic−/fulvic-like matters and clays. This study is helpful for deeply understanding the multimedia-crossing environmental behavior of BBS-DOMs in the surface environment.
研究领域:
环境科学
·
土壤学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Environmental Science & Technology Letters
·
2017
·
IF 5.308
Jun-Cheng Han,Guo-Jun Chen,Li-Ping Qin,Yang Mu
Cr isotope fractionation during microbial reduction processes is commonly recognized as a promising tool in biogeochemistry and bioremediation. However, the mechanism of Cr isotope fractionation during microbial reduction is poorly understood. In this work, the relationship between the bacterial respiratory pathway and Cr isotope fractionation was investigated in Shewanella oneidensis MR-1. For comparison with the wild type, a mutant strain (ΔomcA/ΔmtrC) with a deficiency in extracellular Cr(VI) reduction was constructed by deleting the omcA and mtrC genes, which encode the terminal reductase during extracellular reduction. The magnitudes of Cr isotope fractionation (ε) for Cr(VI) reduction by the wild type and ΔomcA/ΔmtrC were −2.42 ± 0.68‰ and −2.70 ± 0.22‰, respectively. Surprisingly, the ε values were not significantly different between the two strains. This suggests that isotope fractionation is independent of the metal respiratory pathway during Cr(VI) reduction by S. oneidensis MR-1. Moreover, a three-step Cr isotope fractionation model that includes uptake, reduction, and efflux was proposed to exist during intracellular Cr(VI) reduction by S. oneidensis MR-1. The developed model provides a better understanding of Cr isotope fractionation during microbial reduction.
研究领域:
生物地球化学
·
环境微生物学
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL GEOLOGY
·
2023
·
IF 3.9
Liuwei Wang,Jiameng Guo,Daniel C.W. Tsang,Deyi Hou
Stable isotope is a potent geochemical tracer unveiling the dynamic sources of cadmium (Cd) in the environment. However, the sorption process of aqueous Cd onto solid surfaces (e.g., soil) fractionates isotopic signatures, which makes it difficult to interpret its sources and migration processes. Understanding how Cd fractionates during sorption to soil minerals, therefore, provides necessary data to open the isotope fractionation black box of liquid-solid phase partition of Cd. In this study, we explored isotopic fractionation characteristics during Cd sorption to typical soil minerals. Distinct Cd isotope fractionation was observed during sorption, including goethite ( ∆ 114 / 110 Cd solid − solution = − 0.51 ∼ − 0.47 ‰ ), montmorillonite ( − 0.34 ∼ − 0.32 ‰ ), quartz ( − 0.34 ∼ − 0.30 ‰ ), gibbsite ( − 0.29 ∼ − 0.25 ‰ ), and kaolinite ( − 0.09 ∼ − 0.07 ‰ ), where lighter isotopes tended to be preferentially sorbed to the solid phase in a reversible manner. We've also conducted a field survey in a historical flooding-affected region to explore Cd isotopic compositions of soil samples adjacent to a polluted creek. Distinct isotopic signatures for surficial soils and deep soils were observed, which was depicted by a binary mixing mode. Leaching of Cd from mine tailings to the creek, as well as its re-adsorption to soil during historical flooding events both led to preferential enrichment of light isotopes in the solid phase, which was consistent with findings from lab sorption experiments. Mineralogical analyses including EPMA, TOF-SIMS, Mössbauer spectra, XRD, and chemical extraction tests, were applied to unveil how Cd was bound to soil minerals at field. Possible linkage between lab and field data were discussed on the basis of these findings. Results from this study are encouraging for future application of Cd isotopes for source tracing.
研究领域:
环境科学
·
地球化学
·
土壤学
✓ 已验证
产品关联
DOI
高影响因子
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