Pub Date : 2026-03-01Epub Date: 2026-01-08DOI: 10.1016/j.orggeochem.2026.105127
Alice Fradet , Philippe Schaeffer , Leo-Paul Magnin , Lauriane Lenen , Jan Pańczak , Bernard Gomez , Vincent Grossi , Pierre Adam
Although the presence of sulfur in amber has been previously reported, its origins and nature are not precisely known. The recent identification by NMR of sulfides related to tricyclic resin acids in a Cretaceous amber sample unambiguously showed that sulfur occurs in amber as organic sulfur compounds (OSC), at least to some extent. Molecular investigation of a large set of ambers from various botanical/geological origins and ages using GC–MS revealed that OSC are relatively widespread in ambers which was previously unknown. Their proportions relative to non-sulfurized terpenoids are variable among amber samples, and some samples proved to be devoid of OSC. In addition, it has been shown that OSC in ambers present a wide structural diversity, and comprise compounds related to tricyclic resin acids and labdanoids. Several structures could be proposed notably based on comparison with sulfurized labdanoids previously identified in sulfur-rich sediments. Laboratory sulfurization experiments involving functionalized diterpenoids from the resins of Cedrus atlantica and Araucaria columnaris and polysulfides successfully resulted in the formation of OSC identical or analogous to the natural compounds occurring in amber. This validates the predominant proposed pathways for the formation of OSC from amber. The early diagenetic sulfurization of diterpenoids in resin thus appears to be a key geochemical process influencing amber composition and contributing to the molecular diversity observed in fossil resins. The diverse OSC occurring in several amber types could potentially be used as geochemical markers of specific palaeoenvironments where sulfates are available and where the conditions of sedimentation promote, at least locally or in microenvironments, the establishment of anaerobic conditions favourable for the development of sulfate-reducing microorganisms.
{"title":"The widespread occurrence and wide structural diversity of sulfurized diterpenoids in ambers","authors":"Alice Fradet , Philippe Schaeffer , Leo-Paul Magnin , Lauriane Lenen , Jan Pańczak , Bernard Gomez , Vincent Grossi , Pierre Adam","doi":"10.1016/j.orggeochem.2026.105127","DOIUrl":"10.1016/j.orggeochem.2026.105127","url":null,"abstract":"<div><div>Although the presence of sulfur in amber has been previously reported, its origins and nature are not precisely known. The recent identification by NMR of sulfides related to tricyclic resin acids in a Cretaceous amber sample unambiguously showed that sulfur occurs in amber as organic sulfur compounds (OSC), at least to some extent. Molecular investigation of a large set of ambers from various botanical/geological origins and ages using GC–MS revealed that OSC are relatively widespread in ambers which was previously unknown. Their proportions relative to non-sulfurized terpenoids are variable among amber samples, and some samples proved to be devoid of OSC. In addition, it has been shown that OSC in ambers present a wide structural diversity, and comprise compounds related to tricyclic resin acids and labdanoids. Several structures could be proposed notably based on comparison with sulfurized labdanoids previously identified in sulfur-rich sediments. Laboratory sulfurization experiments involving functionalized diterpenoids from the resins of <em>Cedrus atlantica</em> and <em>Araucaria columnaris</em> and polysulfides successfully resulted in the formation of OSC identical or analogous to the natural compounds occurring in amber. This validates the predominant proposed pathways for the formation of OSC from amber. The early diagenetic sulfurization of diterpenoids in resin thus appears to be a key geochemical process influencing amber composition and contributing to the molecular diversity observed in fossil resins. The diverse OSC occurring in several amber types could potentially be used as geochemical markers of specific palaeoenvironments where sulfates are available and where the conditions of sedimentation promote, at least locally or in microenvironments, the establishment of anaerobic conditions favourable for the development of sulfate-reducing microorganisms.</div></div>","PeriodicalId":400,"journal":{"name":"Organic Geochemistry","volume":"213 ","pages":"Article 105127"},"PeriodicalIF":2.5,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146035819","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}
Pub Date : 2026-03-01Epub Date: 2025-12-24DOI: 10.1016/j.orggeochem.2025.105124
Gemma Baker , James Bendle , Lydia K. Greene , Kweku Afrifa Yamoah , Matthew Allison , Sarah E. Greene
The diet of an animal reflects its species’ ecology and local food availability and is often a key metric for monitoring the health and welfare of endangered species. However, determining diets across individuals and through space and time, is an inherent challenge within ecology, being expensive and time-intensive to accomplish with observations. Faeces offer the opportunity for non-invasive sample collection and can provide a snapshot of the ingested diet of the producer. In modern ecology, faecal samples have been a prime target for genetic analyses of diet and the gut microbiome. Here, however, we explore whether high molecular weight (HMW) n-alkane biomarkers extracted from faeces can provide useful information about diet. HMW n-alkanes are commonly employed in palaeoecological reconstructions. Combining faecal HMW n-alkane analyses with gut microbiome composition and detailed foraging data applied to two species of lemur in captivity with access to naturalized forest enclosures, we show that recovered HMW n-alkanes are completely dietary in origin and not correlated to the gut microbiome. Signatures are significantly different between our two focal lemur species and seasons, reflecting differences in ingested diet. It is possible to infer changes in the relative contributions of major plant parts, particularly leaves and fruits, based on the faecal HMW n-alkane concentrations. Whereas n-alkane signatures alone are perhaps ill-suited to pinpoint plant species in animals with complex herbivorous diets, when integrated with other complementary methodologies can provide a more comprehensive dietary reconstruction. HMW n-alkanes are simple to identify and measure; only requiring commonly available and relatively affordable analytical chemistry instruments (e.g. GC-FID). Beyond discussing downstream uses of our methodology to captive and wild lemurs, other primates and herbivorous and omnivorous animals globally, our pilot study hints at the promise of the organic geochemist’s toolkit applied to dietary ecology.
{"title":"Faecal n-alkanes differ significantly between two lemur species reflecting differences in consumed diet","authors":"Gemma Baker , James Bendle , Lydia K. Greene , Kweku Afrifa Yamoah , Matthew Allison , Sarah E. Greene","doi":"10.1016/j.orggeochem.2025.105124","DOIUrl":"10.1016/j.orggeochem.2025.105124","url":null,"abstract":"<div><div>The diet of an animal reflects its species’ ecology and local food availability and is often a key metric for monitoring the health and welfare of endangered species. However, determining diets across individuals and through space and time, is an inherent challenge within ecology, being expensive and time-intensive to accomplish with observations. Faeces offer the opportunity for non-invasive sample collection and can provide a snapshot of the ingested diet of the producer. In modern ecology, faecal samples have been a prime target for genetic analyses of diet and the gut microbiome. Here, however, we explore whether high molecular weight (HMW) <em>n</em>-alkane biomarkers extracted from faeces can provide useful information about diet. HMW <em>n-</em>alkanes are commonly employed in palaeoecological reconstructions. Combining faecal HMW <em>n</em>-alkane analyses with gut microbiome composition and detailed foraging data applied to two species of lemur in captivity with access to naturalized forest enclosures, we show that recovered HMW <em>n</em>-alkanes are completely dietary in origin and not correlated to the gut microbiome. Signatures are significantly different between our two focal lemur species and seasons, reflecting differences in ingested diet. It is possible to infer changes in the relative contributions of major plant parts, particularly leaves and fruits, based on the faecal HMW <em>n</em>-alkane concentrations. Whereas <em>n</em>-alkane signatures alone are perhaps ill-suited to pinpoint plant species in animals with complex herbivorous diets, when integrated with other complementary methodologies can provide a more comprehensive dietary reconstruction. HMW <em>n</em>-alkanes are simple to identify and measure; only requiring commonly available and relatively affordable analytical chemistry instruments (e.g. GC-FID). Beyond discussing downstream uses of our methodology to captive and wild lemurs, other primates and herbivorous and omnivorous animals globally, our pilot study hints at the promise of the organic geochemist’s toolkit applied to dietary ecology.</div></div>","PeriodicalId":400,"journal":{"name":"Organic Geochemistry","volume":"213 ","pages":"Article 105124"},"PeriodicalIF":2.5,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145947984","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}
Pub Date : 2026-02-01Epub Date: 2026-01-11DOI: 10.1016/j.orggeochem.2026.105126
Yongbin Quan , Yiming Hu , Jinhai Yang , Xi’nong Xie , Lei Tuo , Fang Hao , Heqing Feng
The Qiongdongnan Basin exhibits substantial heterogeneity in hydrocarbon composition and origin. Accurately characterizing this variation is critical for refining hydrocarbon generation models in marginal basins. The depositional facies of source rocks fundamentally control the composition and genetic types of hydrocarbons, yet this critical constraint remains poorly understood. To address this gap, biomarker profiling via GC–MS, and δ13C analysis of individual n-alkanes, benzenes, and toluene via GC-IRMS were conducted on three major thermogenic accumulations. Results identify three distinct genetic gas types tied to depositional environments: (1) Y13 is coal-type gas derived from paralic facies source rocks with dominate higher plant input, deposited under oxygenated, non-stratified conditions; (2) L17 also exhibit coal-type gas, but was derived from terrigenous-marine facies source rocks deposited in a suboxic environment with reduced higher plant input; and (3) B21 represents oil-type gas derived from shallow marine facies source rocks deposited in suboxic-dysoxic setting with further reduce terrigenous input. All hydrocarbons originate from the Oligocene Yacheng Formation, with heterogeneity arising from spatially varying depositional facies within the basin, ranging from paralic in the west to shallow marine in the east, correlating with the earlier regional subsidence and marine transgression in the east. This facies-controlled mechanism differs from traditional models that attribute gas variations to maturity, source rock intervals, or post-generation modification. This study provides a template for interpreting hydrocarbon compositions and genetic types, offering a refined framework for source rock evaluation and resource assessment in analogous marginal basins worldwide.
{"title":"Three genetic types of natural gas derived from the Oligocene Yacheng Formation deposited in various environments within the Qiongdongnan Basin, South China Sea","authors":"Yongbin Quan , Yiming Hu , Jinhai Yang , Xi’nong Xie , Lei Tuo , Fang Hao , Heqing Feng","doi":"10.1016/j.orggeochem.2026.105126","DOIUrl":"10.1016/j.orggeochem.2026.105126","url":null,"abstract":"<div><div>The Qiongdongnan Basin exhibits substantial heterogeneity in hydrocarbon composition and origin. Accurately characterizing this variation is critical for refining hydrocarbon generation models in marginal basins. The depositional facies of source rocks fundamentally control the composition and genetic types of hydrocarbons, yet this critical constraint remains poorly understood. To address this gap, biomarker profiling via GC–MS, and δ<sup>13</sup>C analysis of individual <em>n</em>-alkanes, benzenes, and toluene via GC-IRMS were conducted on three major thermogenic accumulations. Results identify three distinct genetic gas types tied to depositional environments: (1) Y13 is coal-type gas derived from paralic facies source rocks with dominate higher plant input, deposited under oxygenated, non-stratified conditions; (2) L17 also exhibit coal-type gas, but was derived from terrigenous-marine facies source rocks deposited in a suboxic environment with reduced higher plant input; and (3) B21 represents oil-type gas derived from shallow marine facies source rocks deposited in suboxic-dysoxic setting with further reduce terrigenous input. All hydrocarbons originate from the Oligocene Yacheng Formation, with heterogeneity arising from spatially varying depositional facies within the basin, ranging from paralic in the west to shallow marine in the east, correlating with the earlier regional subsidence and marine transgression in the east. This facies-controlled mechanism differs from traditional models that attribute gas variations to maturity, source rock intervals, or post-generation modification. This study provides a template for interpreting hydrocarbon compositions and genetic types, offering a refined framework for source rock evaluation and resource assessment in analogous marginal basins worldwide.</div></div>","PeriodicalId":400,"journal":{"name":"Organic Geochemistry","volume":"212 ","pages":"Article 105126"},"PeriodicalIF":2.5,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145972763","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}
The central Congo Basin is home to the world’s largest tropical peatland complex and is covered with swamp forest. In the face of climate change and future human activities in the region, it is important to understand the factors that determine the nature and dynamics of the peatland vegetation cover. One way to gain insight into these factors is to reconstruct the history of the central Congo Basin peatlands. Analysing lipid biomarkers extracted from peat cores such as plant wax n-alkanes enables past environmental and climatic conditions to be reconstructed. However, there is currently no information on how the production of plant waxes by different plant species influences the abundance and isotopic composition of n-alkanes in peat and other archives in the Congo Basin. In this study we analysed plant wax n-alkane abundances, δ13C and δD values according to photosynthetic pathways (C3 vs. C4), angiosperm subclasses (dicotyledons vs. monocotyledons), and source water δD values in the dominant plant types (trees, shrubs, and herbs) in the peatland area of the Cuvette Department in the Republic of the Congo. Our dataset enables the definition of a new n-alkane distribution index, named GRIND, that distinguishes between C3 (mostly dicotyledons) and C4 (monocotyledons) plants as follows: (n-C27 + n-C33 + n-C35)/(n-C25 + n-C27 + n-C29 + n-C31 + n-C33 + n-C35). This index may therefore be used to analyse Central African peat deposits and derive the relative abundance of C3 and C4 plant waxes in the past, independently of δ13C measurements. Furthermore, δ13C values from the central Congo Basin and other African sites suggest that environments with high relative humidity (> 80%) are characterised by very negative δ13C values (i.e., < –37‰) of n-C29 and n-C31 alkanes. This observation highlights the potential of n-alkane δ13C in deriving climatic information under high relative humidity conditions in Central African lowlands, and contribute to palaeo-climatic reconstructions. Finally, the δD values of n-C29 and n-C31 alkanes demonstrate that, despite contrasting apparent fractionation values associated with photosynthetic pathways and plant functional types — which can be accounted for using δ13C and pollen data in sedimentary deposits — they reliably reflect the δD of environmental water. This confirms that plant wax n-alkane δD values are effective tools for reconstructing palaeo-climatic changes in equatorial regions.
{"title":"Plant-wax n-alkanes from the central Congo Basin as palaeo-environmental and -climatic proxies","authors":"Mélanie Guardiola , Gaël U.D. Bouka , Carolia Abaye , Johanna Menges , Frauke Rostek , Guillaume Leduc , Edouard Bard , Enno Schefuß , Yannick Garcin","doi":"10.1016/j.orggeochem.2025.105092","DOIUrl":"10.1016/j.orggeochem.2025.105092","url":null,"abstract":"<div><div>The central Congo Basin is home to the world’s largest tropical peatland complex and is covered with swamp forest. In the face of climate change and future human activities in the region, it is important to understand the factors that determine the nature and dynamics of the peatland vegetation cover. One way to gain insight into these factors is to reconstruct the history of the central Congo Basin peatlands. Analysing lipid biomarkers extracted from peat cores such as plant wax <em>n-</em>alkanes enables past environmental and climatic conditions to be reconstructed. However, there is currently no information on how the production of plant waxes by different plant species influences the abundance and isotopic composition of <em>n-</em>alkanes in peat and other archives in the Congo Basin. In this study we analysed plant wax <em>n-</em>alkane abundances, δ<sup>13</sup>C and δD values according to photosynthetic pathways (C<sub>3</sub> vs. C<sub>4</sub>), angiosperm subclasses (dicotyledons vs. monocotyledons), and source water δD values in the dominant plant types (trees, shrubs, and herbs) in the peatland area of the Cuvette Department in the Republic of the Congo. Our dataset enables the definition of a new <em>n</em>-alkane distribution index, named GRIND, that distinguishes between C<sub>3</sub> (mostly dicotyledons) and C<sub>4</sub> (monocotyledons) plants as follows: (<em>n-</em>C<sub>27</sub> + <em>n-</em>C<sub>33</sub> + <em>n-</em>C<sub>35</sub>)/(<em>n-</em>C<sub>25</sub> + <em>n-</em>C<sub>27</sub> + <em>n-</em>C<sub>29</sub> + <em>n-</em>C<sub>31</sub> + <em>n-</em>C<sub>33</sub> + <em>n-</em>C<sub>35</sub>). This index may therefore be used to analyse Central African peat deposits and derive the relative abundance of C<sub>3</sub> and C<sub>4</sub> plant waxes in the past, independently of δ<sup>13</sup>C measurements. Furthermore, δ<sup>13</sup>C values from the central Congo Basin and other African sites suggest that environments with high relative humidity (> 80%) are characterised by very negative δ<sup>13</sup>C values (i.e., < –37‰) of <em>n-</em>C<sub>29</sub> and <em>n-</em>C<sub>31</sub> alkanes. This observation highlights the potential of <em>n-</em>alkane δ<sup>13</sup>C in deriving climatic information under high relative humidity conditions in Central African lowlands, and contribute to palaeo-climatic reconstructions. Finally, the δD values of <em>n</em>-C<sub>29</sub> and <em>n</em>-C<sub>31</sub> alkanes demonstrate that, despite contrasting apparent fractionation values associated with photosynthetic pathways and plant functional types — which can be accounted for using δ<sup>13</sup>C and pollen data in sedimentary deposits — they reliably reflect the δD of environmental water. This confirms that plant wax <em>n</em>-alkane δD values are effective tools for reconstructing palaeo-climatic changes in equatorial regions.</div></div>","PeriodicalId":400,"journal":{"name":"Organic Geochemistry","volume":"212 ","pages":"Article 105092"},"PeriodicalIF":2.5,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145659138","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}
Pub Date : 2026-02-01Epub Date: 2025-12-15DOI: 10.1016/j.orggeochem.2025.105123
C. Cerda-Peña , S.J. Feakins , M.C. Aranda , D.H. Pérez , P. Pérez-Portilla , A. Aránguiz-Acuña , S. Contreras
Plant waxes, widely used as biomarkers for paleoenvironmental reconstructions in boreal peatlands, remain relatively understudied in Andean “bofedales” peat meaning that their application in these ecosystems requires a better understanding of local vegetation. This study therefore compares four plant wax classes – n-alkanoic acids, n-alkanes, n-alkanols, and sterols – in leaves and sheaths of Distichia muscoides and Oxychloe andina, that form cushions (or mounds), in a bofedal in northern Chile. Analyses indicate that wax concentrations were higher in D. muscoides and n-alkanoic acids were dominant in both species and showed significant differences in the average chain length (ACL; O. andina = 27.3, σ = 0.78; D. muscoides = 26.8, σ = 0.18; p < 0.05), while those for the n-alkanes were similar. Mean n-alkanol abundances were significantly higher in D. muscoides (171.5; σ = 76.7 μg/g) than in O. andina (32.1; σ = 53.5 μg/g, p < 0.05) and among sterols, β-sitosterol was the most abundant in both species. Plant wax distributions were similar between organs, except for the ACL of the n-alkanoic acids in D. muscoides (leaves = 26.8, σ = 0.2; sheaths = 25.9, σ = 0.1; p < 0.001). For both species, leaf–sheath differences in plant wax abundance and size suggest that leaves contribute most to peat (∼4× n-alkanoic acids, ∼2× n-alkanes). The study reports four compound classes detected in “cushion” plants towards their application in the bofedales peat of the Andean Altiplano. In particular we find that n-alkanes show minimal differences between species, suggesting suitability for testing for compound-specific isotopic analysis-based paleoclimate proxies in bofedales. β-Sitosterol is highly abundant and may serve as a biomarker for the presence of the studied species. Overall, the bofedales have potential as archives of plant wax from these cushion plants towards paleoenvironmental reconstructions.
植物蜡被广泛用作北方泥炭地古环境重建的生物标志物，但在安第斯“bofedales”泥炭地的研究相对较少，这意味着它们在这些生态系统中的应用需要更好地了解当地的植被。因此，这项研究比较了在智利北部一处森林中形成垫（或土丘）的Distichia muscoides和Oxychloe andina的叶子和鞘中的四种植物蜡类——正烷酸、正烷烃、正烷醇和甾醇。分析结果表明，蜡质浓度较高，正烷酸在两种中均占优势，平均链长差异显著（ACL: O. andina = 27.3, σ = 0.78； D. muscoides = 26.8, σ = 0.18; p < 0.05），而正烷烃的链长差异无统计学意义。正烷醇的平均丰度（171.5,σ = 76.7 μg/g）显著高于白腹草（32.1,σ = 53.5 μg/g, p < 0.05），在甾醇中，β-谷甾醇在两种植物中含量最高。植物蜡质在各器官间的分布基本一致，除了正烷酸的ACL（叶片= 26.8,σ = 0.2；鞘= 25.9,σ = 0.1; p < 0.001）。对于这两个物种，叶鞘在植物蜡丰度和大小上的差异表明，叶片对泥炭的贡献最大（~ 4×正烷酸，~ 2×正烷烃）。该研究报告了在“缓冲”植物中检测到的四种化合物类，它们将在安第斯高原的泥炭中应用。特别是，我们发现正构烷烃在物种之间的差异很小，这表明适合测试基于化合物特定同位素分析的古气候代用物。β-谷甾醇含量丰富，可作为研究物种存在的生物标志物。综上所述，这些岩斑有可能作为这些垫层植物的植物蜡的档案，用于古环境重建。
{"title":"Plant waxes of co-dominant cushion plant species in a bofedal peatland on the Andean Altiplano","authors":"C. Cerda-Peña , S.J. Feakins , M.C. Aranda , D.H. Pérez , P. Pérez-Portilla , A. Aránguiz-Acuña , S. Contreras","doi":"10.1016/j.orggeochem.2025.105123","DOIUrl":"10.1016/j.orggeochem.2025.105123","url":null,"abstract":"<div><div>Plant waxes, widely used as biomarkers for paleoenvironmental reconstructions in boreal peatlands, remain relatively understudied in Andean “bofedales” peat meaning that their application in these ecosystems requires a better understanding of local vegetation. This study therefore compares four plant wax classes – <em>n</em>-alkanoic acids, <em>n</em>-alkanes, <em>n</em>-alkanols, and sterols – in leaves and sheaths of <em>Distichia muscoides</em> and <em>Oxychloe andina</em>, that form cushions (or mounds), in a bofedal in northern Chile. Analyses indicate that wax concentrations were higher in <em>D. muscoides</em> and <em>n</em>-alkanoic acids were dominant in both species and showed significant differences in the average chain length (ACL; <em>O. andina</em> = 27.3, σ = 0.78; <em>D. muscoides</em> = 26.8, σ = 0.18; p < 0.05), while those for the <em>n</em>-alkanes were similar. Mean <em>n</em>-alkanol abundances were significantly higher in <em>D. muscoides</em> (171.5; σ = 76.7 μg/g) than in <em>O. andina</em> (32.1; σ = 53.5 μg/g, <em>p</em> < 0.05) and among sterols, <em>β</em>-sitosterol was the most abundant in both species. Plant wax distributions were similar between organs, except for the ACL of the <em>n</em>-alkanoic acids in <em>D. muscoides</em> (leaves = 26.8, σ = 0.2; sheaths = 25.9, σ = 0.1; <em>p</em> < 0.001). For both species, leaf–sheath differences in plant wax abundance and size suggest that leaves contribute most to peat (∼4× <em>n</em>-alkanoic acids, ∼2× <em>n</em>-alkanes). The study reports four compound classes detected in “cushion” plants towards their application in the bofedales peat of the Andean Altiplano. In particular we find that <em>n</em>-alkanes show minimal differences between species, suggesting suitability for testing for compound-specific isotopic analysis-based paleoclimate proxies in bofedales. <em>β</em>-Sitosterol is highly abundant and may serve as a biomarker for the presence of the studied species. Overall, the bofedales have potential as archives of plant wax from these cushion plants towards paleoenvironmental reconstructions.</div></div>","PeriodicalId":400,"journal":{"name":"Organic Geochemistry","volume":"212 ","pages":"Article 105123"},"PeriodicalIF":2.5,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145880961","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}
Pub Date : 2026-02-01Epub Date: 2025-12-24DOI: 10.1016/j.orggeochem.2025.105120
Tim Marten , Lorenz Schwark
Hopanoids are among the most abundant natural products on Earth. Despite their widespread occurrence in soils, coals, sediments, sedimentary rocks and crude oils, their diagenetic pathways have not been fully resolved. Here, we present a diverse suite of aliphatic and aromatic hopanoids from a single sample of a thermally immature Lower Jurassic black shale. All extended saturated and Δ17,21-unsaturated hopanoid species occur as 2α-methyl analogues, which exhibit a carbon number distribution matching that of the desmethyl hopanes. This suggests similar precursor organisms for 2-methyl and desmethyl hopanoids favouring the genesis of C30+ hopanoids. Potential precursor organisms are assumed to include marine diazotrophic cyanobacteria or α-proteobacteria both affiliated with the nitrogen-cycle. Polyaromatic hopanoids occur in high concentrations, especially the C24 tetraaromatic hopane, and deviate from the extended hopanoid species in terms of carbon number distribution and A-ring methylation, indicating different origins for these hopanoids. The high aromaticity of these hopanoids suggests an origin from soil bacteria, which is consistent with an accelerated hydrological cycle and evidence for enhanced soil erosion during the early Toarcian. The co-occurrence of a multitude of hopanoid species within one sample exemplifies the complexity of hopanoid transformation products during stages of very early diagenesis. Preservation of this hopanoid complexity during diagenesis in the geosphere over a period of 183 Ma is exceptional because labile hopanoids commonly are destroyed by thermal maturation. It must be assumed that other sediments contained comparably complex hopanoid distributions, which upon later diagenesis suffered reduced variability seen in most sedimentary rocks and oils.
{"title":"A plethora of hopanoid transformation products co-exist in a thermally immature Jurassic black shale I: hopanoid hydrocarbons","authors":"Tim Marten , Lorenz Schwark","doi":"10.1016/j.orggeochem.2025.105120","DOIUrl":"10.1016/j.orggeochem.2025.105120","url":null,"abstract":"<div><div>Hopanoids are among the most abundant natural products on Earth. Despite their widespread occurrence in soils, coals, sediments, sedimentary rocks and crude oils, their diagenetic pathways have not been fully resolved. Here, we present a diverse suite of aliphatic and aromatic hopanoids from a single sample of a thermally immature Lower Jurassic black shale. All extended saturated and Δ<sup>17,21</sup>-unsaturated hopanoid species occur as 2α-methyl analogues, which exhibit a carbon number distribution matching that of the desmethyl hopanes. This suggests similar precursor organisms for 2-methyl and desmethyl hopanoids favouring the genesis of C<sub>30+</sub> hopanoids. Potential precursor organisms are assumed to include marine diazotrophic cyanobacteria or α-proteobacteria both affiliated with the nitrogen-cycle. Polyaromatic hopanoids occur in high concentrations, especially the C<sub>24</sub> tetraaromatic hopane, and deviate from the extended hopanoid species in terms of carbon number distribution and A-ring methylation, indicating different origins for these hopanoids. The high aromaticity of these hopanoids suggests an origin from soil bacteria, which is consistent with an accelerated hydrological cycle and evidence for enhanced soil erosion during the early Toarcian. The co-occurrence of a multitude of hopanoid species within one sample exemplifies the complexity of hopanoid transformation products during stages of very early diagenesis. Preservation of this hopanoid complexity during diagenesis in the geosphere over a period of 183 Ma is exceptional because labile hopanoids commonly are destroyed by thermal maturation. It must be assumed that other sediments contained comparably complex hopanoid distributions, which upon later diagenesis suffered reduced variability seen in most sedimentary rocks and oils.</div></div>","PeriodicalId":400,"journal":{"name":"Organic Geochemistry","volume":"212 ","pages":"Article 105120"},"PeriodicalIF":2.5,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145837441","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}
Pub Date : 2026-02-01Epub Date: 2025-12-24DOI: 10.1016/j.orggeochem.2025.105121
Tim Marten , Lorenz Schwark
Hopanoids are ubiquitous in sediments and sedimentary rocks and are commonly applied tools for paleoenvironment reconstruction. Biohopanoids during diagenesis transform to geohopanoids when they successively lose their structural diversity. Prior to elevated thermal maturity, where only hopanes and benzohopanes persist, a large variety of intermediate hopanoid transformation products can be intermittently abundant in immature sediments. We presented in a companion paper the highly diverse hopanoid hydrocarbon inventory in one immature black shale sample from the Toarcian Posidonia Shale at Hondelage, NW-Germany that was deposited under euxinic conditions. Here, the focus is on the plethora of oxo- and thiohopanoids co-existing in the same sample. The formation of hopanoic acids requires oxic conditions whereas thiohopanoid require sulfidic conditions. These contrasting requirements suggest spatial and temporal separation of hopanoic acid versus thiohopanoid formation prior to or after incorporation into the sediment. Hopanoic acids presumably form in the oxic upper water column with potential minor contributions from oxic microniches and/or seasonally induced brief suboxic events at the sediment/water interface. In contrast, thiohopanoids presumably originate within the sulfidic water column and/or the sediment. Persistent euxinic conditions during deposition of the Posidonia Shale at Hondelage favoured formation of a variety of thiohopanoids in a shallow marine setting below a salinity-stratified water column. Thiohopanoids include previously unidentified hop-17(21)-ene thiolanes and hopane thiophenes extending to C38. Since hopanoids extending past C35 are absent for other hopanoid species, extended hopane thiophenes likely result from microbially mediated early diagenetic alkylation at the C35 position. Hopanoic acids as well as thiohopanoids occur as 2-methyl analogues and exhibit elevated abundances of C33 homologues, which dominate in desmethyl hopanoids. Precursor organisms for 2-methyl hopanoids are most likely nitrogen cycle-affiliated α-proteobacteria and/or diazotrophic cyanobacteria.
{"title":"A plethora of hopanoid transformation products co-exist in a thermally immature Jurassic black shale II: Oxo- and thiohopanoids","authors":"Tim Marten , Lorenz Schwark","doi":"10.1016/j.orggeochem.2025.105121","DOIUrl":"10.1016/j.orggeochem.2025.105121","url":null,"abstract":"<div><div>Hopanoids are ubiquitous in sediments and sedimentary rocks and are commonly applied tools for paleoenvironment reconstruction. Biohopanoids during diagenesis transform to geohopanoids when they successively lose their structural diversity. Prior to elevated thermal maturity, where only hopanes and benzohopanes persist, a large variety of intermediate hopanoid transformation products can be intermittently abundant in immature sediments. We presented in a companion paper the highly diverse hopanoid hydrocarbon inventory in one immature black shale sample from the Toarcian Posidonia Shale at Hondelage, NW-Germany that was deposited under euxinic conditions. Here, the focus is on the plethora of oxo- and thiohopanoids co-existing in the same sample. The formation of hopanoic acids requires oxic conditions whereas thiohopanoid require sulfidic conditions. These contrasting requirements suggest spatial and temporal separation of hopanoic acid versus thiohopanoid formation prior to or after incorporation into the sediment. Hopanoic acids presumably form in the oxic upper water column with potential minor contributions from oxic microniches and/or seasonally induced brief suboxic events at the sediment/water interface. In contrast, thiohopanoids presumably originate within the sulfidic water column and/or the sediment. Persistent euxinic conditions during deposition of the Posidonia Shale at Hondelage favoured formation of a variety of thiohopanoids in a shallow marine setting below a salinity-stratified water column. Thiohopanoids include previously unidentified hop-17(21)-ene thiolanes and hopane thiophenes extending to C<sub>38</sub>. Since hopanoids extending past C<sub>35</sub> are absent for other hopanoid species, extended hopane thiophenes likely result from microbially mediated early diagenetic alkylation at the C35 position. Hopanoic acids as well as thiohopanoids occur as 2-methyl analogues and exhibit elevated abundances of C<sub>33</sub> homologues, which dominate in desmethyl hopanoids. Precursor organisms for 2-methyl hopanoids are most likely nitrogen cycle-affiliated α-proteobacteria and/or diazotrophic cyanobacteria.</div></div>","PeriodicalId":400,"journal":{"name":"Organic Geochemistry","volume":"212 ","pages":"Article 105121"},"PeriodicalIF":2.5,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145837382","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}
Pub Date : 2026-02-01Epub Date: 2025-11-06DOI: 10.1016/j.orggeochem.2025.105088
Aljasil Chirakkal , Ekaterina Kulakova , Calin C. Steindal , Jago J. Birk , Anton Anoikin , Redzhep Kurbanov , Petr Sosin , Peixian Shu , David K. Wright
This study presents a multi‑proxy investigation of loess–paleosol sequences from the Khovaling Loess Plateau (KLP) in Southern Tajikistan to explore long‑term human-environment interactions during the Middle Pleistocene. This region has been the focus of numerous archaeological projects since Soviet times, as it contains evidence of some of the oldest (∼0.9 Ma) hominin occupations in Central Asia and is one of the key regions connecting eastern Asia to centers of hominin evolution that lie to the west. Previous archaeological expeditions have discovered rich collections of stone tools from alternating non-pedogenically modified loess and paleosol sequences at the archaeological sites of Karatau, Lakhuti, Obi-Mazar, and Kuldura. We analyzed lipid biomarkers such as n‑alkanes, polycyclic aromatic hydrocarbons (PAHs), together with newly generated stable isotopes (δ13C, δ15N), magnetic susceptibility, and archaeological assemblages from three sites: Obi-Mazar/Lakhuti (on‑site), and non-artifact-bearing strata from Kuldara (near‑site) and Khonako‑II (off‑site), focusing on pedocomplexes (PCs) 4, 5, and 6 and their intercalated loess layers. High odd-over-even predominance (OEP) and average chain lengths (ACL) suggest that soil organic matter is predominantly derived from higher-order terrestrial plants, with better preservation in paleosols compared to loess layers. The inverse correlations of δ13C with TOC and C/N reflect organic matter degradation, while elevated δ15N in paleosols suggests enhanced nitrogen cycling under warmer and drier conditions. Magnetic susceptibility and δ13C trends reveal a progressive shift toward open grassland ecosystems since ∼0.8 Ma, with intensified pedogenesis during interglacial stages MIS 11, 13, and 15. The spatial distribution of PAH concentrations and lithic artifact densities further highlights human-environment interactions in the KLP locality. Obi-Mazar exhibits abundant lithic materials and high PAH levels, indicating repeated occupation and frequent burning in a resource‑rich riverine setting. Kuldara exhibits moderate PAHs but minimal artifacts, whereas Khonako-II records only a minimal level of signals, reflecting a decrease in human impact with distance from the water source. Together, these findings demonstrate that Early Paleolithic hominins preferentially occupied ecologically stable, pedogenically developed zones during interglacial phases, contributing to localized fire regimes and shaping their landscapes. This study provides a refined paleoenvironmental framework for understanding hominin adaptations in Central Asia during the Middle Pleistocene.
{"title":"Geochemical records from loess sediments provide insights into early hominin influence on the landscape in the Khovaling region of Southern Tajikistan, Central Asia","authors":"Aljasil Chirakkal , Ekaterina Kulakova , Calin C. Steindal , Jago J. Birk , Anton Anoikin , Redzhep Kurbanov , Petr Sosin , Peixian Shu , David K. Wright","doi":"10.1016/j.orggeochem.2025.105088","DOIUrl":"10.1016/j.orggeochem.2025.105088","url":null,"abstract":"<div><div>This study presents a multi‑proxy investigation of loess–paleosol sequences from the Khovaling Loess Plateau (KLP) in Southern Tajikistan to explore long‑term human-environment interactions during the Middle Pleistocene. This region has been the focus of numerous archaeological projects since Soviet times, as it contains evidence of some of the oldest (∼0.9 Ma) hominin occupations in Central Asia and is one of the key regions connecting eastern Asia to centers of hominin evolution that lie to the west. Previous archaeological expeditions have discovered rich collections of stone tools from alternating non-pedogenically modified loess and paleosol sequences at the archaeological sites of Karatau, Lakhuti, Obi-Mazar, and Kuldura. We analyzed lipid biomarkers such as <em>n</em>‑alkanes, polycyclic aromatic hydrocarbons (PAHs), together with newly generated stable isotopes (δ<sup>13</sup>C, δ<sup>15</sup>N), magnetic susceptibility, and archaeological assemblages from three sites: Obi-Mazar/Lakhuti (on‑site), and non-artifact-bearing strata from Kuldara (near‑site) and Khonako‑II (off‑site), focusing on pedocomplexes (PCs) 4, 5, and 6 and their intercalated loess layers. High odd-over-even predominance (OEP) and average chain lengths (ACL) suggest that soil organic matter is predominantly derived from higher-order terrestrial plants, with better preservation in paleosols compared to loess layers. The inverse correlations of δ<sup>13</sup>C with TOC and C/N reflect organic matter degradation, while elevated δ<sup>15</sup>N in paleosols suggests enhanced nitrogen cycling under warmer and drier conditions. Magnetic susceptibility and δ<sup>13</sup>C trends reveal a progressive shift toward open grassland ecosystems since ∼0.8 Ma, with intensified pedogenesis during interglacial stages MIS 11, 13, and 15. The spatial distribution of PAH concentrations and lithic artifact densities further highlights human-environment interactions in the KLP locality. Obi-Mazar exhibits abundant lithic materials and high PAH levels, indicating repeated occupation and frequent burning in a resource‑rich riverine setting. Kuldara exhibits moderate PAHs but minimal artifacts, whereas Khonako-II records only a minimal level of signals, reflecting a decrease in human impact with distance from the water source. Together, these findings demonstrate that Early Paleolithic hominins preferentially occupied ecologically stable, pedogenically developed zones during interglacial phases, contributing to localized fire regimes and shaping their landscapes. This study provides a refined paleoenvironmental framework for understanding hominin adaptations in Central Asia during the Middle Pleistocene.</div></div>","PeriodicalId":400,"journal":{"name":"Organic Geochemistry","volume":"212 ","pages":"Article 105088"},"PeriodicalIF":2.5,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145787553","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}
Pub Date : 2026-02-01Epub Date: 2025-12-17DOI: 10.1016/j.orggeochem.2025.105098
Ahmed Khairy , Clement N. Uguna , Waleed Sh. El Diasty , Kenneth E. Peters , Christopher H. Vane , Colin E. Snape , Sherif Farouk , Will Meredith
Biomarkers are powerful tools to assess thermal maturity of oil and rock extracts and for oil-source rock correlation. While temperature effects on biomarker evolution have been widely studied, the impact of pressure remains largely underexplored. This study examines the effect of high water pressure (up to 900 bar) on biomarker maturation in expelled oil and extracted bitumen from pyrolysis experiments on a rock sample from the Campanian–Maastrichtian Duwi Formation, Red Sea Basin, Egypt. Extracted bitumens exhibited higher maturity under anhydrous conditions compared to low-pressure hydrous samples, and this was more pronounced at 350°C. The extracted bitumen displayed higher biomarker maturity ratios than the corresponding expelled oil at 350°C, likely due to prolonged interactions of the bitumen with the rock mineral matrix. In contrast, δ13C values were similar for extracted bitumen and the corresponding expelled oil. At 320°C, high pressure reduced values of biomarker maturity ratios, particularly C31–C35 homohopane isomerisation, Ts/Tm, Ts/H30, and C29Ts/H29 ratios, whereas sterane ratios remained unaffected. At 350°C, pressure effects were less significant, with some anomalous variations, suggesting a non-systematic influence on biomarker maturation at higher temperatures. These findings demonstrate the complex role of pressure in biomarker evolution, emphasising the need to consider pressure in biomarker-based maturity assessment, particularly in overpressured basins and deep petroleum systems, where high pressure may be a dominant factor. Based on 12 source-related biomarker and isotopic ratios, chemometric analysis reveals that artificially generated oils and South Malak-1 oils from southwestern onshore Gulf of Suez are quite different, and both groups differ significantly from other natural oils from the central and northern parts of the basin. This may be due to facies variations and the effects of mixing from multiple source horizons under natural subsurface conditions.
{"title":"Effect of water pressure on bitumen and expelled oil biomarker evolution: Insights from laboratory simulation experiments","authors":"Ahmed Khairy , Clement N. Uguna , Waleed Sh. El Diasty , Kenneth E. Peters , Christopher H. Vane , Colin E. Snape , Sherif Farouk , Will Meredith","doi":"10.1016/j.orggeochem.2025.105098","DOIUrl":"10.1016/j.orggeochem.2025.105098","url":null,"abstract":"<div><div>Biomarkers are powerful tools to assess thermal maturity of oil and rock extracts and for oil-source rock correlation. While temperature effects on biomarker evolution have been widely studied, the impact of pressure remains largely underexplored. This study examines the effect of high water pressure (up to 900 bar) on biomarker maturation in expelled oil and extracted bitumen from pyrolysis experiments on a rock sample from the Campanian–Maastrichtian Duwi Formation, Red Sea Basin, Egypt. Extracted bitumens exhibited higher maturity under anhydrous conditions compared to low-pressure hydrous samples, and this was more pronounced at 350°C. The extracted bitumen displayed higher biomarker maturity ratios than the corresponding expelled oil at 350°C, likely due to prolonged interactions of the bitumen with the rock mineral matrix. In contrast, δ<sup>13</sup>C values were similar for extracted bitumen and the corresponding expelled oil. At 320°C, high pressure reduced values of biomarker maturity ratios, particularly C<sub>31</sub>–C<sub>35</sub> homohopane isomerisation, Ts/Tm, Ts/H<sub>30</sub>, and C<sub>29</sub>Ts/H<sub>29</sub> ratios, whereas sterane ratios remained unaffected. At 350°C, pressure effects were less significant, with some anomalous variations, suggesting a non-systematic influence on biomarker maturation at higher temperatures. These findings demonstrate the complex role of pressure in biomarker evolution, emphasising the need to consider pressure in biomarker-based maturity assessment, particularly in overpressured basins and deep petroleum systems, where high pressure may be a dominant factor. Based on 12 source-related biomarker and isotopic ratios, chemometric analysis reveals that artificially generated oils and South Malak-1 oils from southwestern onshore Gulf of Suez are quite different, and both groups differ significantly from other natural oils from the central and northern parts of the basin. This may be due to facies variations and the effects of mixing from multiple source horizons under natural subsurface conditions.</div></div>","PeriodicalId":400,"journal":{"name":"Organic Geochemistry","volume":"212 ","pages":"Article 105098"},"PeriodicalIF":2.5,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145787554","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}
Pub Date : 2026-02-01Epub Date: 2025-12-12DOI: 10.1016/j.orggeochem.2025.105122
J.G. Altmann , B. Jansen , M. Palviainen , K. Kalbitz
Cutin and suberin have frequently been used as plant-part specific biomarkers in sediments and soils. The two most commonly used analytical methods described in the literature to study cutin and suberin are pyrolysis with tetramethylammonium hydroxide (TMAH) and base-catalyzed methanolysis with potassium hydroxide (KOH). Both methods are usually combined with gas chromatography (GC) to analyze and identify the resulting compounds. However, until now, a critical assessment of the compatibility of the results obtained by both methods was missing.
Here, we compared the two techniques on Scots pine (Pinus sylvestris) and Norway spruce (Picea abies) roots and needles that decomposed for three years in litterbags. KOH methanolysis released a broader suite of long-chain alcohols, diols and mid-chain hydroxy-fatty acids, identifying 19 tissue-specific biomarkers, whereas pyrolysis with TMAH yielded 10 diagnostic compounds; only seven markers overlapped. The concentrations of analogous molecules decreased in different ways over time, preventing any generalizable conclusions from being drawn about the stability of the original biopolymers.Thus, the methods are complementary rather than interchangeable. Pyrolysis yields fewer, more temporally stable signals and requires substantially less sample preparation per analysis, making it well suited to quantitative source apportionment; by contrast, methanolysis involves multi-step sample preparation and provides richer structural detail that facilitates biomarker discovery across taxa and matrices.
{"title":"Comparison of Curie-point pyrolysis with tetramethylammonium hydroxide (TMAH) and base catalyzed methanolysis in leaf and root biomarker decomposition studies","authors":"J.G. Altmann , B. Jansen , M. Palviainen , K. Kalbitz","doi":"10.1016/j.orggeochem.2025.105122","DOIUrl":"10.1016/j.orggeochem.2025.105122","url":null,"abstract":"<div><div>Cutin and suberin have frequently been used as plant-part specific biomarkers in sediments and soils. The two most commonly used analytical methods described in the literature to study cutin and suberin are pyrolysis with tetramethylammonium hydroxide (TMAH) and base-catalyzed methanolysis with potassium hydroxide (KOH). Both methods are usually combined with gas chromatography (GC) to analyze and identify the resulting compounds. However, until now, a critical assessment of the compatibility of the results obtained by both methods was missing.</div><div>Here, we compared the two techniques on Scots pine (<em>Pinus sylvestris</em>) and Norway spruce (<em>Picea abies</em>) roots and needles that decomposed for three years in litterbags. KOH methanolysis released a broader suite of long-chain alcohols, diols and mid-chain hydroxy-fatty acids, identifying 19 tissue-specific biomarkers, whereas pyrolysis with TMAH yielded 10 diagnostic compounds; only seven markers overlapped. The concentrations of analogous molecules decreased in different ways over time, preventing any generalizable conclusions from being drawn about the stability of the original biopolymers.Thus, the methods are complementary rather than interchangeable. Pyrolysis yields fewer, more temporally stable signals and requires substantially less sample preparation per analysis, making it well suited to quantitative source apportionment; by contrast, methanolysis involves multi-step sample preparation and provides richer structural detail that facilitates biomarker discovery across taxa and matrices.</div></div>","PeriodicalId":400,"journal":{"name":"Organic Geochemistry","volume":"212 ","pages":"Article 105122"},"PeriodicalIF":2.5,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145787555","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}
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