Organic Geochemistry最新文献_第2页

Isotopic signatures of organic matter in the Upper Miocene–Pliocene Elbistan coal seam (Turkey): Insights from δ13C and δ15N variability 上中新世—上新世Elbistan煤层有机质同位素特征：来自δ13C和δ15N变率的启示

IF 2.5 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Organic Geochemistry

Pub Date : 2025-10-27 DOI: 10.1016/j.orggeochem.2025.105086

Hatice Kara , Mehmet Ali Ertürk , Leyla Kalender , Cihan Yalçın , Mehmet Deniz Turan , Emine Cicioğlu Sütçü

This study examines the stable carbon (δ¹³C) and nitrogen (δ¹⁵N) isotope compositions of coal samples from the Upper Miocene–Pliocene (Neogene) Elbistan Basin, Turkey, to constrain the sources of organic matter and the depositional conditions of peat formation. A vertical sequence of samples collected from the Kışlaköy open-pit mine was analysed for total carbon and nitrogen contents, C/N ratios, and δ¹³C–δ¹⁵N values. The δ¹³C values range from −28.09 ‰ to −16.99 ‰, while δ¹⁵N values vary between 1.97 ‰ and 4.99 ‰. The carbon isotope data indicate a predominantly C₃-type plant origin for the organic matter, with minor C₄ contributions inferred from samples exhibiting enriched δ¹³C signatures. Although some δ¹³C enrichment may partly reflect microbial alteration of organic matter, the overall values remain consistent with a dominant C₃ vegetation signal. Elevated δ¹⁵N values suggest fluctuating redox conditions and microbial nitrogen cycling during peat accumulation. In comparison with other Turkish lignite basins and global coal deposits, the Elbistan samples display a broader isotopic range, reflecting a more complex paleoenvironmental evolution. The data suggest that the coal beds formed mainly in freshwater mire settings, where fluctuating water tables, variable redox conditions, and occasional inputs from C₄ plants influenced peat accumulation. These results provide new insights into the paleobotanical and geochemical history of the basin and demonstrate the value of stable isotope analysis for reconstructing depositional environments in coal-bearing successions.

研究了土耳其Elbistan盆地上中新世—上新世（新近系）煤样的稳定碳（δ13C）和氮（δ15N）同位素组成，以限制有机质来源和泥炭形成的沉积条件。对采自Kışlaköy露天矿的垂直序列样品进行了总碳、总氮含量、C/N比值和δ13C -δ15N值分析。δ13C值在−28.09‰~−16.99‰之间，δ15N值在1.97‰~ 4.99‰之间。碳同位素数据显示有机质以c3型植物来源为主，δ13C特征丰富的样品显示少量的C4贡献。虽然部分δ13C富集可能部分反映了有机质的微生物蚀变，但总体值与C3植被信号保持一致。δ15N值的升高表明泥炭积累过程中氧化还原条件和微生物氮循环的波动。与土耳其其他褐煤盆地和全球煤层相比，Elbistan样品显示出更广泛的同位素范围，反映了更复杂的古环境演化。数据表明，煤层主要形成于淡水沼泽环境，其中波动的地下水位、可变的氧化还原条件和偶尔的C4植物输入影响了泥炭的积累。这些结果为盆地的古植物学和地球化学历史提供了新的认识，并证明了稳定同位素分析在重建含煤演替沉积环境中的价值。

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引用次数: 0

Transformation of lignin and lipid biomarkers through degradation of plant tissues and soil organic carbon in a salt marsh-mangrove ecotone 盐沼-红树林交错带植物组织和土壤有机碳降解过程中木质素和脂质生物标志物的转化

IF 2.5 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Organic Geochemistry

Pub Date : 2025-10-14 DOI: 10.1016/j.orggeochem.2025.105084

Prakhin Assavapanuvat , Joshua L. Breithaupt , Ding He , Ralph N. Mead , Thomas S. Bianchi

The poleward expansion of mangroves into native salt marshes, because of global warming, has the potential to alter coastal soil organic carbon (SOC) stocks and composition. However, its effects on organic carbon decomposition remain largely unknown. This study compared concentrations and degradation indices of lignin, sterol, triterpenoid, and n-alkane biomarkers between live-and-dead leaf-and-root tissues and SOC down to 45-cm depth across habitats dominated by two mangrove and two salt marsh species in Apalachicola coastal wetlands, Florida, USA. A significant increase in n-alkanes and lignin oxidation products was observed following the senescence of Avicennia germinans mangrove tissues. Dead leaves of all four plant species, especially Spartina alterniflora and Juncus roemerianus salt marshes, became hotspots of fungal colonization as indicated by elevated ergosterol content. Interpretation of biomarker degradation ratios was complicated by their large difference between living root and leaf endmembers. In soil cores from all plant habitats, the predominance of tetracyclic triterpenoid degradation products (tetracylic:pentacylic ratio = 0.6–518) indicated prevalent anaerobic decomposition, agreeing with higher cholestanol/cholesterol and stigmastanol/stigmasterol ratios in SOC (0.53 ± 0.29 and 1.14 ± 0.83), relative to plant tissues (0.16 ± 0.17 and 0.57 ± 0.44, respectively). In contrast, the presence of pentacyclic degradation products in deep mangrove and salt marsh soils suggested localized aerobic degradation, likely due to subsurface oxygen release from plant roots. In conclusion, salt marsh-to-A. germinans mangrove replacement modified degradability of surface litter, yet degradation of deep SOC was more dependent on biogeochemical characteristics of the soils.

由于全球变暖，红树林向极地扩张成为原生盐沼，有可能改变沿海土壤有机碳（SOC）储量和组成。然而，它对有机碳分解的影响在很大程度上仍然未知。本研究比较了美国佛罗里达州Apalachicola沿海湿地2种红树林和2种盐沼物种45 cm深度下叶、根活组织中木质素、甾醇、三萜和正构烷烃生物标志物的浓度和降解指数。在红树组织衰老后，正构烷烃和木质素氧化产物显著增加。麦角甾醇含量的升高表明，4种植物的枯叶都成为真菌定植的热点，尤其是互花米草和秋葵盐沼。生物标志物降解率的解释由于其在活着的根和叶末端成员之间的巨大差异而变得复杂。在所有植物生境的土壤岩心中，四环三萜降解产物（四环：五环比= 0.6-518）的优势表明厌氧分解普遍存在，这与有机碳中胆固醇/胆固醇和豆甾醇/豆甾醇的比值（0.53±0.29和1.14±0.83）相对于植物组织（分别为0.16±0.17和0.57±0.44）较高一致。相比之下，深红树林和盐沼土壤中五环降解产物的存在表明局部有氧降解，可能是由于植物根系释放的地下氧。综上所述，盐沼对a。红树林的更替改变了地表凋落物的可降解性，但深层有机碳的降解更多地取决于土壤的生物地球化学特征。

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引用次数: 0

Exploring clumped isotope fractionation of organic molecules using density functional theory 利用密度泛函理论探索有机分子的团块同位素分馏

IF 2.5 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Organic Geochemistry

Pub Date : 2025-10-07 DOI: 10.1016/j.orggeochem.2025.105062

Alexis Gilbert , Jakub Surma , Naizhong Zhang , Sebastian Danielache , Qi Liu

The measurement of doubly-substituted (‘clumped’) isotopologues provides important information regarding the source, sink, and potentially the temperature of formation of a given molecule. While currently limited to small molecules such as methane or carbonate, recent technological developments are expected to expand the range of molecules studied, paving the way for clumped isotope measurements in various organic compounds. Theoretical calculations, including those based on density functional theory (DFT), can serve as guidelines for future methodological developments. However, these calculations have so far been reported for a small number of organic molecules and clumping types.

Here, we report DFT calculations for DD, ¹³CD, ¹³C¹³C, ¹³C¹⁵N, and ¹³C¹⁸O clumping in organic molecules. Using 32 model molecules, we calculate a total of 143 Δ values (Δ representing the deviation from the stochastic distribution due to equilibrium isotope effects) at temperatures ranging from 300 K to 1000 K. The overall trend follows: ΔDD > Δ¹³CD > Δ¹³C¹⁸O > Δ¹³C¹³C ≈ Δ¹³C¹⁵N, with values decreasing as temperature increases. Through multiple correlation analysis, we demonstrate that the reduced mass of the atoms, bond multiplicity, and hybridization collectively explain 80 % of the differences observed between bond types. Given current analytical uncertainties, the potential for a geothermometer is primarily limited to DD and ¹³CD clumping, while ¹³C¹³C, ¹³C¹⁵N, and ¹³C¹⁸O clumping could be applicable at low temperatures (typically 100 K) or with instrumental precision one order of magnitude higher.

The calculations presented here provide a framework to assess the instrumental precision required for utilizing clumped isotopes in organic molecules as geothermometers. Future improvements in analytical techniques and computational methodologies could further refine these predictions and broaden the applicability of clumped isotope thermometry in organic geochemistry.

双取代（“团块”）同位素的测量提供了关于给定分子的源、汇和潜在形成温度的重要信息。虽然目前仅限于甲烷或碳酸盐等小分子，但最近的技术发展有望扩大研究分子的范围，为各种有机化合物的团块同位素测量铺平道路。理论计算，包括基于密度泛函理论（DFT）的理论计算，可以作为未来方法论发展的指导方针。然而，到目前为止，这些计算只报道了少数有机分子和结块类型。本文报道了有机分子中DD、13CD、13C13C、13C15N和13C18O聚块的DFT计算。使用32个模型分子，我们在300 K到1000 K的温度范围内计算了143个Δ值（Δ表示由于平衡同位素效应而与随机分布的偏差）。总体趋势如下：ΔDD >； Δ13CD >； Δ13C18O >； Δ13C13C≈Δ13C15N，随温度升高而减小。通过多重相关分析，我们证明原子质量的减少、键的多样性和杂化共同解释了80%的键类型之间的差异。鉴于目前的分析不确定性，地温计的潜力主要局限于DD和13CD的聚类，而13C13C、13C15N和13C18O的聚类可能适用于低温（通常为100 K）或仪器精度高一个数量级。这里提出的计算提供了一个框架，以评估利用有机分子中的团块同位素作为地温计所需的仪器精度。分析技术和计算方法的未来改进可以进一步完善这些预测，并扩大团块同位素测温在有机地球化学中的适用性。

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引用次数: 0

Magma-induced thermal alteration in Devonian organic-rich rocks (Paraná Basin, Brazil): molecular transformations and clay-catalyzed maturation 巴西帕拉纳<e:1>盆地泥盆系富有机质岩石的岩浆热蚀变：分子转化和粘土催化成熟

IF 2.5 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Organic Geochemistry

Pub Date : 2025-09-25 DOI: 10.1016/j.orggeochem.2025.105083

Lucas Pinto Heckert Bastos , René Rodrigues , Carmen Lucia Ferreira Alferes , Debora Bonfim Neves da Silva , Danielle da Costa Cavalcante , Guilherme Brugger Lemos , Sergio Bergamaschi , Egberto Pereira

Several studies have examined how high heating rates influence the molecular composition of organic matter, particularly in geological settings where magma interacts with organic-rich rocks. In Brazil, such interactions have been extensively documented in the Paraná Basin. However, the behavior of geochemical proxies under intense thermal stress, as well as the natural chemical products generated through the thermal cracking of organic matter, are not yet fully understood. In this study, a combination of bulk and molecular geochemical data from 233 m of Devonian strata in the Paraná Basin—intersected by two dolerite sills measuring 3.0 m and 0.86 m in thickness—was used to assess the extent and effects of magmatic heating on originally immature organic matter. The work includes a large dataset of total organic carbon and Rock-Eval pyrolysis along with thermal-maturity-related molecular geochemical proxies. The thermal evolution of organic matter was better assessed using methylated aromatic hydrocarbons, as saturate hydrocarbons are less resistant to high temperatures and may not respond well to rapid heating. The borehole profile was subdivided into four stages (I–IV) based on the response of geochemical proxies to thermal stress. The intermediate zone (Stages II and III) showed elevated MPI-1 (methylphenanthrene index) values and distorted saturate hydrocarbon ratios. Additionally, samples from this high thermal stress zone of the sills showed a significantly higher abundance of dimethyl alkanes—compared to less altered samples dominated by monomethyl alkanes. Multiple alkyl substitutions have been naturally favored in high-temperature zones by acidic clay mineral catalysis and sustained thermal stress, potentially from percolating hydrothermal fluids. The thermal alteration zone exceeds the expected halo from the two sills intersecting the borehole, which is interpreted as resulting from the percolation of hydrothermal fluids and/or a complex igneous body geometry.

几项研究考察了高加热速率如何影响有机质的分子组成，特别是在岩浆与富有机质岩石相互作用的地质环境中。在巴西，这种相互作用在帕拉纳盆地得到了广泛的记录。然而，地球化学指标在强热应力作用下的行为以及有机质热裂解产生的天然化学产物尚不完全清楚。本研究利用paran盆地233m泥盆纪地层的体积地球化学和分子地球化学数据——由厚度分别为3.0 m和0.86 m的两个白云岩断层相交——来评估岩浆加热对原始未成熟有机质的程度和影响。这项工作包括总有机碳和岩石热解的大型数据集以及与热成熟度相关的分子地球化学指标。甲基化芳烃可以更好地评估有机质的热演化，因为饱和烃对高温的耐受性较差，对快速加热的反应可能不太好。根据地球化学指标对热应力的响应，将井眼剖面划分为4个阶段（I-IV）。中间段（II期和III期）甲基菲指数（MPI-1）升高，饱和烃比例扭曲。此外，与以单甲基烷烃为主的变化较少的样品相比，来自技能高热应力区的样品显示出明显更高的二甲基烷烃丰度。在酸性粘土矿物催化和持续的热应力作用下（可能来自渗透热液），多烷基取代在高温区域自然有利。热蚀变带超出了与钻孔相交的两个井的预期晕，这被解释为由热液流体的渗透和/或复杂的火成岩体几何形状造成的。

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引用次数: 0

Generation and maturation of diamondoids for petroleum reservoirs in the Tarim Basin, NW China 塔里木盆地油气储层金刚石类化合物的生成与成熟

IF 2.5 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Organic Geochemistry

Pub Date : 2025-09-18 DOI: 10.1016/j.orggeochem.2025.105080

Shuang Yu , Yuanyuan Bian , Chenxi Zhou , Wenyu Huang , Haizu Zhang , Zhongyiao Xiao , Changchun Pan

Diamondoid generation and maturation behaviors in natural system remain unresolved. Oils/condensates from the Tarim Basin have elevated diamondoid concentrations. Diamondoid concentrations and maturity ratios for 167 oils/condensates from the Tarim Basin were used to document diamondoid generation and maturation in combination with the maturity frameworks of the deep source rocks. These samples include 29 Kuqa condensates from the Kuqa Depression, and 45 Tabei oils/condensates from the Tabei (Northern Tarim) Uplift and neighboring slope area and 93 Tazhong oils/condensates from the Tazhong (Central Tarim) Uplift and neighboring slope area of the cratonic region. The main observations are: (1) Concentration distributions of 4- + 3-methyldiamantane (4 + 3MD) for the Kuqa condensates and the Tabei and Tazhong oils/condensates are consistent with the maturity frameworks of the Triassic source rocks in the Kuqa Depression and the Cambrian source rocks in the cratonic region of the Tarim Basin from basin modeling, respectively. Concentrations of total adamantanes (As), total diamantanes (Ds) and 4 + 3MD have a close linear positive correlation with each other for these studied oils/condensates. These results suggest that diamondoids were generated at increasing rate with increasing maturity of these deep source rocks and did not decompose in these source rocks at maturity up to %Ro 4.0–4.5 in the Tarim Basin. (2) The effectiveness of the nine diamondoid maturity ratios (MAI, MDI, DMAI-1, DMAI-2, TMAI-1, TMAI-2, DMDI-1, DMDI-2 and EAI) increases, while the influence of source facies on these maturity ratios, in particular on the last three ratios (DMDI-1, DMDI-2 and EAI) decreases with increasing maturity of the source rocks based on Pearson correlation coefficients (r) between each other among the nine maturity ratios and concentrations of As, Ds and 4 + 3MD and As/Ds ratio. (3) The maturities of the deep source rocks for the studied samples decrease in the sequence of the Kuqa condensates > the Tazhong oils/condensates > the Tabei oils/condensates based on the maximum values and ranges of the nine diamondoid maturity ratios and the r values between each other among the nine maturity ratios, concentrations of As, Ds and 4 + 3MD. and the As/Ds ratio. This sequence provides a constraint in basin modeling on the relative maturities of the Triassic source rocks in the Kuqa Depression and Cambrian source rocks in the cratonic region.

自然系统中金刚石的生成和成熟行为尚未解决。塔里木盆地的油/凝析油中金刚石含量升高。利用塔里木盆地167种油/析油的金刚石浓度和成熟度比值，结合深层烃源岩的成熟格架，记录了塔里木盆地深层烃源岩中金刚石的生成和成熟过程。其中，库车坳陷库车凝析油29份，塔北隆起及邻坡区塔北凝析油45份，塔中隆起及克拉通区邻坡区塔中凝析油93份。主要观察结果如下：(1)库车凝析油和塔北、塔中油/凝析油4 + 3-甲基diamantane （4 + 3MD）浓度分布分别符合库车坳陷三叠系烃源岩和塔里木盆地克拉通区寒武系烃源岩的成熟度格架。总金刚烷（As）、总金刚烷（Ds）和4 + 3MD的浓度之间存在密切的线性正相关关系。这些结果表明，塔里木盆地深层烃源岩中金刚石类化合物的生成速率随着烃源岩成熟度的增加而增加，并且在成熟度高达%Ro 4.0 ~ 4.5的烃源岩中未发生分解。(2) 9种金刚石成熟度比（MAI、MDI、DMAI-1、DMAI-2、TMAI-1、TMAI-2、DMDI-1、DMDI-2和EAI）的有效性随着烃源岩成熟度的增加而增强，而烃源岩相对9种成熟度比，尤其是对后3种成熟度比（DMDI-1、DMDI-2和EAI）的影响随着烃源岩成熟度的增加而减弱。(3)从9个金刚石成熟度比的最大值和范围、As、Ds和4 + 3MD的浓度及其相互之间的r值来看，研究样品深层烃源岩的成熟度顺序依次为库车油、塔中油、塔北油。As/Ds比值。该层序为库车坳陷三叠系烃源岩和克拉通区寒武系烃源岩相对成熟度的盆地模拟提供了约束条件。

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引用次数: 0

Geochemistry articles – July 2025 地球化学文章- 2025年7月

IF 2.5 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Organic Geochemistry

Pub Date : 2025-09-15 DOI: 10.1016/j.orggeochem.2025.105055

引用次数: 0

Geochemical characteristics of Longtan transitional shale gas in the western Hubei Basin, northwest Middle Yangtze Block: Implications for the origin and carbon isotopes 鄂西中扬子地块西北部龙潭过渡型页岩气地球化学特征及其成因与碳同位素意义

IF 2.5 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Organic Geochemistry

Pub Date : 2025-09-01 DOI: 10.1016/j.orggeochem.2025.105059

Weiqing Liu , Haiyang Li , Yu Qiao , Wei Wu , Jienan Pan , Chuanlong Mou , Jianxin Yao , Yao Chen , Changsong Lin

Shale gas geochemical characteristics are critical for genetic identification and enrichment mechanism analysis. Current research focuses predominantly on marine shale gas, whereas studies on transitional shale gas (particularly the Permian Longtan Formation in South China) remain relatively limited, which constrains our understanding of the geochemical characteristics and genesis of transitional shale gases. The geochemical characteristics of transitional shale gas from the upper Permian Longtan Formation in western Hubei Province indicate that the organic matter is predominantly sapropelic, with some humic organic matter. The gas composition of the Longtan Formation consists primarily of CH₄, with a low content of C₂H₆. The δ¹³C_CH4 values range from −25.40 ‰ to −21.70 ‰, the δ¹³C_C2H6 values range from –32.00 ‰ to −27.02 ‰, and the δ²H_CH4 values range from −124.01 ‰ to −119.46 ‰. These findings imply that shale gas is composed mainly of oil-type gas of thermal origin, with a potentially minor presence of mixed gas. Isotope analysis of the shale gas reveals that it has undergone reversal (δ¹³C_CH4 > δ¹³C_C2H6), which is attributed to the cracking of liquid hydrocarbons under overmature conditions. The CO₂ content ranges from 0.21 % to 2.33 % and the δ¹³C_CO2 values range from −21.80 ‰ to −19.00 ‰, suggesting that the CO₂ in the study area is of organic thermal origin. Additionally, a geochemical evolution pattern suggests that the gas composition of different sedimentary phases is controlled by the type of kerogen and the degree of thermal evolution. The multistage cracking of organic matter thermal evolution products caused the dynamic changes in carbon isotopes.

页岩气地球化学特征是页岩气成因识别和富集机理分析的重要依据。目前的研究主要集中在海相页岩气，而对过渡型页岩气（特别是华南二叠系龙潭组）的研究相对有限，这限制了我们对过渡型页岩气地球化学特征和成因的认识。鄂西地区上二叠统龙潭组过渡性页岩气地球化学特征表明，其有机质以腐泥质为主，含少量腐殖质有机质。龙潭组气体成分以CH4为主，C2H6含量较低。δ13CCH4的取值范围为- 25.40‰~ - 21.70‰，δ13CC2H6的取值范围为-32.00‰~ - 27.02‰，δ2HCH4的取值范围为- 124.01‰~ - 119.46‰。这些发现表明，页岩气主要由油型热成因气组成，可能存在少量混合气。页岩气同位素分析表明，页岩气发生了δ13CCH4 >； δ13CC2H6反转，这是由于过成熟条件下液态烃裂解所致。CO2含量在0.21% ~ 2.33%之间，δ13CCO2值在- 21.80‰~ - 19.00‰之间，表明研究区CO2为有机热成因。地球化学演化模式表明，不同沉积相的天然气组成受干酪根类型和热演化程度的控制。有机质热演化产物的多阶段裂解导致了碳同位素的动态变化。

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引用次数: 0

Compositional convergence of dissolved organic matter from root litter to rhizosphere soil in a semiarid grassland of North China 华北半干旱草地凋落根向根际土壤溶解有机质的组成收敛性

IF 2.5 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Organic Geochemistry

Pub Date : 2025-09-01 DOI: 10.1016/j.orggeochem.2025.105061

Xiaohan Mo , Zongxiao Zhang , Mengke Wang , Qiang Zhang , Guodong Sun , Weifeng Hu , Guoping Chen , Deliang Kong , Chengcheng Dong , Hui Zeng , Junjian Wang

The transformation of litter-derived dissolved organic matter (DOM) in soils is important for carbon cycling in terrestrial ecosystems. However, the linkage between root litter- and rhizosphere soil-derived DOM remains unclear. In this study, using ultrahigh-resolution mass spectrometry and metagenomics, we evaluated the DOM in paired roots and rhizosphere soils for herbaceous plants in a semiarid grassland and their biogeochemical processes. Analyses revealed a decoupling between root- and rhizosphere soil-derived DOM despite being directly attached, with a considerable loss of root-derived aliphatics and proteins, and production of highly unsaturated, aromatic, and carboxyl-rich compounds. From roots to rhizosphere soils, DOM shifted toward a more uniform molecular composition, which was likely the result of a more “specialized” utilization of root-derived DOM and a more “generalized” utilization of rhizosphere soil-derived DOM by the rhizosphere microbial community. Overall, DOM transformation at the root-soil interface occurred along two principal dimensions: 1) the dimension of “root-to-soil variation” with “lability” and “aromaticity” as two end members, and 2) the dimension of “interspecies variation” dominated by bulk and optical DOM components. These findings suggest that root- and rhizosphere soil-derived DOM constitute two distinct carbon sources for rhizosphere microbial communities and provide a framework for future investigations into DOM dynamics and ecosystem functioning at the plant-soil interface.

土壤中凋落物源溶解有机质（DOM）的转化对陆地生态系统的碳循环具有重要意义。然而，根凋落物和根际土壤DOM之间的联系尚不清楚。本研究利用超高分辨率质谱技术和宏基因组学技术，研究了半干旱草地草本植物根际和根际配对土壤中的DOM及其生物地球化学过程。分析表明，尽管根际土壤来源的DOM直接附着，但根际土壤来源的DOM之间存在解耦，根际土壤来源的脂肪和蛋白质大量流失，并产生高度不饱和、芳香和富含羧基的化合物。从根到根际土壤，DOM的分子组成趋于统一，这可能是根际微生物群落对根源DOM的利用更加“专门化”，对根际土壤源DOM的利用更加“普遍化”的结果。总体而言，根-土界面DOM的转化主要发生在两个维度上：1)以“不稳定性”和“芳香性”为两端成员的“根-土变异”维度，2)以体积和光学DOM成分为主的“种间变异”维度。这些发现表明，根际和根际土壤来源的DOM构成了根际微生物群落的两种不同的碳源，并为未来研究植物-土壤界面DOM动态和生态系统功能提供了框架。

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引用次数: 0

Deamination of alicyclic and aromatic amines under geologically relevant hydrothermal conditions 与地质相关的热液条件下脂环胺和芳香胺的脱胺作用

IF 2.5 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Organic Geochemistry

Pub Date : 2025-08-31 DOI: 10.1016/j.orggeochem.2025.105060

Yiju Liao , Alexandria Aspin , Xuan Fu , Kirtland Robinson , Ziming Yang

Amines are a particular group of organic compounds of interest to deep-sea biology, organic geochemistry, and astrobiology research, in large part due to their involvement in biological metabolism, such as in the form of amino acids and proteins, participation in the subsurface carbon (C) and nitrogen (N) cycles, as well as their relevance to biomolecular precursors on early Earth and potential biosignatures beyond Earth. Although there have been many studies on the deamination of amines under hydrothermal conditions, few have determined the relative deamination rates and degradation mechanisms among different amine structures. In this study, we investigate the reaction kinetics and pathways of a group of aromatic and alicyclic amines, including aniline, benzylamine, cyclohexylamine, and cyclohexylmethylamine, under geologically relevant temperatures (200–275 °C) and pH ranges (5–9) for up to 120 h. Among the studied amines, the amine reactivity generally follows a trend of aniline < cyclohexylamine < cyclohexylmethylamine < benzylamine. Alcohols and secondary amines/imines are observed as the major products of amines, whose formation could follow a nucleophilic substitution (S_N1 or S_N2) mechanism. Hydrothermal experiments at different pH also show that deamination occurs more readily under acidic than alkaline hydrothermal conditions, indicating that the aminium form (R-NH₃⁺) accelerates deamination. These results suggest that the kinetics and pathways of hydrothermal amine transformations are controlled by both the amine structure and solution pH, which have implications for predicting the deamination processes of organic N, release of inorganic N (e.g., ammonia), and N cycling in geologically relevant hydrothermal systems.

胺是深海生物学、有机地球化学和天体生物学研究感兴趣的一类特殊有机化合物，这在很大程度上是因为它们参与生物代谢，例如以氨基酸和蛋白质的形式，参与地下碳(C)和氮(N)循环，以及它们与早期地球上的生物分子前体和地球以外潜在的生物特征的相关性。虽然对水热条件下胺类物质的脱氨作用研究较多，但对不同胺类结构间的相对脱氨速率和降解机理的研究较少。在本研究中，我们研究了苯胺、苄胺、环己胺和环己基甲胺等芳香族和脂环类胺在地质相关温度（200-275℃）和pH（5-9）下长达120 h的反应动力学和反应途径。在所研究的胺中，胺的反应性总体上遵循苯胺、环己胺、环己基甲胺和苄胺的变化趋势。醇和仲胺/亚胺是胺的主要产物，其形成遵循亲核取代（SN1或SN2）机制。不同pH条件下的水热实验也表明，酸性水热条件下脱氨比碱性水热条件下更容易发生，说明氨形态（R-NH3+）加速了脱氨。这些结果表明，水热胺转化的动力学和途径受胺结构和溶液pH的共同控制，这对预测地质相关热液系统中有机氮的脱氨过程、无机氮（如氨）的释放和氮循环具有重要意义。

{"title":"Deamination of alicyclic and aromatic amines under geologically relevant hydrothermal conditions","authors":"Yiju Liao , Alexandria Aspin , Xuan Fu , Kirtland Robinson , Ziming Yang","doi":"10.1016/j.orggeochem.2025.105060","DOIUrl":"10.1016/j.orggeochem.2025.105060","url":null,"abstract":"<div><div>Amines are a particular group of organic compounds of interest to deep-sea biology, organic geochemistry, and astrobiology research, in large part due to their involvement in biological metabolism, such as in the form of amino acids and proteins, participation in the subsurface carbon (C) and nitrogen (N) cycles, as well as their relevance to biomolecular precursors on early Earth and potential biosignatures beyond Earth. Although there have been many studies on the deamination of amines under hydrothermal conditions, few have determined the relative deamination rates and degradation mechanisms among different amine structures. In this study, we investigate the reaction kinetics and pathways of a group of aromatic and alicyclic amines, including aniline, benzylamine, cyclohexylamine, and cyclohexylmethylamine, under geologically relevant temperatures (200–275 °C) and pH ranges (5–9) for up to 120 h. Among the studied amines, the amine reactivity generally follows a trend of aniline < cyclohexylamine < cyclohexylmethylamine < benzylamine. Alcohols and secondary amines/imines are observed as the major products of amines, whose formation could follow a nucleophilic substitution (S<sub>N</sub>1 or S<sub>N</sub>2) mechanism. Hydrothermal experiments at different pH also show that deamination occurs more readily under acidic than alkaline hydrothermal conditions, indicating that the aminium form (R-NH<sub>3</sub><sup>+</sup>) accelerates deamination. These results suggest that the kinetics and pathways of hydrothermal amine transformations are controlled by both the amine structure and solution pH, which have implications for predicting the deamination processes of organic N, release of inorganic N (e.g., ammonia), and N cycling in geologically relevant hydrothermal systems.</div></div>","PeriodicalId":400,"journal":{"name":"Organic Geochemistry","volume":"209 ","pages":"Article 105060"},"PeriodicalIF":2.5,"publicationDate":"2025-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144997622","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Corrigendum to “Unravelling the origin of gas in tight sandstones of the Hangjinqi gas field, Ordos Basin, China: New insights from natural gas geochemistry data”. [Org. Geochem. 206 (2025) 105012] 《鄂尔多斯盆地杭锦旗气田致密砂岩气源解析：天然气地球化学数据的新见解》勘误。(Org。地球化学，206 (2025)105012 [j]

IF 2.5 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Organic Geochemistry

Pub Date : 2025-08-27 DOI: 10.1016/j.orggeochem.2025.105051

Yang Qin , Chiyang Liu , Junfeng Zhao , Faqi He , Wei Zhang , Lihua Yang , Nan Du , Deyong Shao

引用次数: 0