Organic Geochemistry最新文献

{"title":"Nitrogen stable isotope patterns in free and protein-bound amino acids of the anoxygenic phototroph, Rhodopseudomonas palustris","authors":"Jenan Kharbush ,&nbsp;Raisha Rahman ,&nbsp;Ann Pearson ,&nbsp;Alice Zhou","doi":"10.1016/j.orggeochem.2025.104945","DOIUrl":"10.1016/j.orggeochem.2025.104945","url":null,"abstract":"<div><div>Compound-specific isotope analysis of amino acids (AAs) can reveal the sources and transformations of nitrogen in ecological and environmental studies. However, there is limited information on microbial patterns of ¹⁵N distributions in AAs and the intracellular biochemical processes that determine these patterns. This leads to gaps in understanding the underlying mechanisms that determine the ¹⁵N content of key N-containing biomarkers. Here we measured δ¹⁵N values of both free and protein-bound amino acids in metabolically flexible <em>Rhodopseudomonas palustris</em> grown photomixotrophically under anoxic conditions. Patterns of ¹⁵N distribution in protein-bound amino acids of <em>R. palustris</em> resemble aerobic phototrophs, implying these microbial groups may be indistinguishable in environmental samples. Intriguingly, free amino acids consistently are <em>ca.</em> 5 ‰ enriched in ¹⁵N relative to protein-bound amino acids; this pattern may provide a new window to understanding intracellular fractionating processes during metabolite recycling and protein synthesis.</div></div>","PeriodicalId":400,"journal":{"name":"Organic Geochemistry","volume":"201 ","pages":"Article 104945"},"PeriodicalIF":2.6,"publicationDate":"2025-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143145072","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}

{"title":"The temporal distributions of seed-plant terpanes in petroleum samples: Implications as oil age-diagnostic biomarkers for crude oils","authors":"Chun Zhu ,&nbsp;Clifford C. Walters ,&nbsp;J. Alex Zumberge ,&nbsp;Marlene Madincea","doi":"10.1016/j.orggeochem.2025.104943","DOIUrl":"10.1016/j.orggeochem.2025.104943","url":null,"abstract":"<div><div>Gymnosperm and angiosperm are sister clades of seed-plants thriving on land since the Carboniferous and Cretaceous, respectively. Both biosynthesize specific terpenoids whose diagenetic hydrocarbon skeletons are preserved in geological samples as molecular fossils of seed-plants. Although the radiation of seed-plants has been well established, the temporal distributions of their biomarkers in geological samples remain poorly characterized. We defined angiosperm and gymnosperm ratios to quantify the relative abundances of seed-plant terpanes and examined the relationship between these ratios and geological age via well-studied, world-wide, petroleum samples deposited in various environments. Although angiosperm ratios show broad ranges in the Cretaceous – Tertiary samples, the Epoch-maxima increase from Early Cretaceous to Paleocene, and from Paleocene to Eocene-Miocene. Gymnosperm ratios remain low pre-Jurassic; however, the Period-maxima significantly increase from pre-Jurassic to Jurassic, and further increase from Jurassic to Cretaceous-Tertiary. These patterns are consistent with seed-plant evolution. We propose three age indicators: 1) O/(O + 29Ts) − an oleanane-based angiosperm ratio to distinguish age of Early Cretaceous or younger vs. Paleocene or younger vs. Eocene or younger; 2) Retene/(Retene + DBT) − a retene-based gymnosperm ratio to differentiate Jurassic or younger vs. Cretaceous or younger; and 3) under marine influence (DBT/P &gt; 0.05), enrichment of retene [Retene/(Retene + DBT) &gt; 0.3] and absence of oleanane [O/(O + 29Ts) &lt; 0.04] indicative of Jurassic – Early Cretaceous. The three new age indicators improve age resolution of published age biomarkers from Era to Period level for oil age differentiation, a critical factor in de-risking petroleum systems.</div></div>","PeriodicalId":400,"journal":{"name":"Organic Geochemistry","volume":"201 ","pages":"Article 104943"},"PeriodicalIF":2.6,"publicationDate":"2025-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143145153","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}

{"title":"Geochemistry Articles – November 2024","authors":"","doi":"10.1016/j.orggeochem.2025.104930","DOIUrl":"10.1016/j.orggeochem.2025.104930","url":null,"abstract":"","PeriodicalId":400,"journal":{"name":"Organic Geochemistry","volume":"201 ","pages":"Article 104930"},"PeriodicalIF":2.6,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143419388","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}

{"title":"Geochemistry Articles – December 2024","authors":"","doi":"10.1016/j.orggeochem.2025.104931","DOIUrl":"10.1016/j.orggeochem.2025.104931","url":null,"abstract":"","PeriodicalId":400,"journal":{"name":"Organic Geochemistry","volume":"201 ","pages":"Article 104931"},"PeriodicalIF":2.6,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143419389","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}

{"title":"Application of biomarker and non-biomarker parameters to assess maturity using the Central Carpathian Paleogene Basin as a case study","authors":"Dorota Staneczek,&nbsp;Leszek Marynowski","doi":"10.1016/j.orggeochem.2025.104933","DOIUrl":"10.1016/j.orggeochem.2025.104933","url":null,"abstract":"<div><div>This study employs an integrated approach to investigate the thermal maturity of sedimentary rocks within the Central Carpathian Paleogene Basin (CCPB) by combining biomarker and non-biomarker parameters. The research primarily applies biomarker ratios based on the distribution of aliphatic and aromatic hydrocarbons and compares them with other paleotemperature indicators such as Rock-Eval pyrolysis. The results reveal a notable thermal gradient across the CCPB. The highest maturity levels are recorded in the Spiš Basin with calculated vitrinite reflectance values exceeding 2.0 %, and the least mature in the Orava Basin and Šariš Upland. The latter two contain unsaturated compounds, indicating immature organic matter. The variations in the paleotemperature pattern emerge from the changing thickness of overlying rocks in these areas. The findings suggest that the calculated vitrinite reflectance derived from the methylphenanthrene index (MPI1) is the most appropriate method for characterizing the broadest maturity range. When comparing the results of the illite/smectite-derived paleotemperatures with biomarker-derived ones, there is a good agreement in the results of the rocks with a higher degree of maturity. In contrast, at lower maturities, the illite/smectite-derived paleotemperatures appear to be overestimated. This study highlights the limitations of using a single maturity indicator and argues for a comprehensive approach combining different parameters to accurately reconstruct paleotemperatures. These results advance our understanding of the geological evolution of the CCPB and provide valuable information for future hydrocarbon exploration in the region. The CCPB is an excellent testing ground for comparing different maturity parameters.</div></div>","PeriodicalId":400,"journal":{"name":"Organic Geochemistry","volume":"201 ","pages":"Article 104933"},"PeriodicalIF":2.6,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143145152","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}

{"title":"Long chain n-alkanes in lake sediment track differences in adjacent land vegetation.","authors":"Bowen Xiao ,&nbsp;Dënë Cheecham-Uhrich ,&nbsp;David C. Eickmeyer ,&nbsp;Linda E. Kimpe ,&nbsp;Vilmantas Prėskienis ,&nbsp;E. Henriikka Kivilä ,&nbsp;Meiling Man ,&nbsp;Myrna J. Simpson ,&nbsp;Irena Creed ,&nbsp;Milla Rautio ,&nbsp;Jules M. Blais","doi":"10.1016/j.orggeochem.2025.104934","DOIUrl":"10.1016/j.orggeochem.2025.104934","url":null,"abstract":"<div><div>We conducted an analysis of <em>n</em>-alkanes, lignin-derived phenols, and other sediment markers from 19 lakes across four ecoregions in Saskatchewan, Canada, spanning from Prairie Grassland to Boreal Upland. Our goal was to establish whether these biomarkers relate to different ecoregions and land cover types (herbaceous plants vs trees) in the catchments of these lakes. Our findings revealed a significant inverse correlation between the proportion of herbaceous plants to trees in a lake’s catchment and the proportion of aquatic <em>n</em>-alkanes <em>P</em>_aq (C₂₃ + C₂₅)/(C₂₃ + C₂₅ + C₂₉ + C₃₁) indicating that aquatic plants contributed proportionally more to sedimentary <em>n</em>-alkanes when the catchments were mostly in Boreal forest. We also observed significant positive correlations between the proportion of herbaceous plants to trees in a lake’s catchment and the <em>n</em>-alkane composition ratios C₃₁/(C₂₇ + C₃₁) and C₃₁/(C₂₇ + C₂₉ + C₃₁), reflecting higher relative inputs of C₃₁ from herbaceous vegetation. These findings suggest that these ratios could potentially be utilized to infer historical land cover composition based on dated sediment records. Moreover, variations in the C₃₁/(C₂₇ + C₃₁) alkane ratio were observed among ecoregions, particularly between Prairie Grassland and the forest-dominated areas. We found no correlations between chlorophyll-<em>a</em> concentrations in lake water and the above-mentioned <em>n</em>-alkane ratios in sediment, suggesting that these ratios primarily reflect land cover composition rather than autochthonous production in the lakes. Additionally, the C/N ratio and δ¹³C were not effective in distinguishing ecoregions or land cover composition, likely due to influences from algal production and perhaps agricultural activities in surrounding farmland. In contrast, lignin-derived phenols in sediments showed relatively little association with their respective ecoregions and appeared to be influenced by decomposition as evidenced by high ratios of carboxylic acids relative to aldehydes (Ad/Al). Overall, our research highlights the potential of <em>n</em>-alkanes as biomarkers for tracking distinct land cover types due to their strong associations with the proportion of grasses and trees.</div></div>","PeriodicalId":400,"journal":{"name":"Organic Geochemistry","volume":"202 ","pages":"Article 104934"},"PeriodicalIF":2.6,"publicationDate":"2025-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143395821","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Discerning diagenetic pathways for discrete sterol precursors","authors":"Kelsey E. Doiron ,&nbsp;Peter K. Bijl ,&nbsp;Thomas Wagner ,&nbsp;Simon C. Brassell","doi":"10.1016/j.orggeochem.2025.104935","DOIUrl":"10.1016/j.orggeochem.2025.104935","url":null,"abstract":"<div><div>Studies of steroidal hydrocarbons in sedimentary sequences have helped elucidate the diagenetic fate of sterols, although discrete aspects of their transformation pathways remain unresolved. Steroidal hydrocarbons are prominent aliphatic hydrocarbons in Campanian to Paleocene sediments (∼78–63 Ma) recovered from the Transkei Basin (Hole U1581B), offshore South Africa, during IODP Expedition 392. Their distributions parallel those observed for other immature marine Cretaceous sediments, comprising C₂₇ to C₂₉ Δ⁴- and Δ⁵-sterenes and Δ^4,22- and Δ^5,22-steradienes, 20S and 20R diasterenes, partially rearranged sterenes (19-nor-5β-methylster-8-enes), and 5α- and 5β-steranes. In the upper Campanian through Danian sediment sequence, the proportion of C₂₈ steradienes (&gt;60%) far exceeds that for sterenes and steranes (∼10–30%) likely reflecting major phytoplankton contributions of their C₂₈ Δ^5,22 sterol precursor. The composition of steroidal hydrocarbons changes systematically with depth matching the succession of proven diagenetic transformations, including progressive increase in 20S/(20S + 20R) diasterenes. The occurrence of partially rearranged sterenes (19-nor-5β-methylster-8-enes) and increasing amounts of diasterenes in the middle Campanian are accompanied by a concomitant decrease in the proportions of sterenes and steradienes. Increasing downcore proportions (∼20%) of C₂₈ steranes and diasterenes indicates a pathway for diagenetic hydrogenation of Δ^4,22- and Δ^5,22-steradienes to Δ⁴- and Δ⁵-sterenes, which are subsequently rearranged to diasterenes or reduced to 5α- and 5β-steranes dependent on the agency of clay catalysis. Hence, contributions from steradienes lead to the diagenetic evolution of the carbon number distributions of steranes and diasterenes as they gradually become an aggregate measure of all sterol precursors.</div></div>","PeriodicalId":400,"journal":{"name":"Organic Geochemistry","volume":"201 ","pages":"Article 104935"},"PeriodicalIF":2.6,"publicationDate":"2025-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143145070","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}

{"title":"Revisiting the fingerprint of organic matters in speleothem by Electron Paramagnetic Resonance","authors":"Yves Perrette ,&nbsp;Hervé Vezin ,&nbsp;Bernard Fanget ,&nbsp;Julia Garagnon ,&nbsp;Jérome Poulenard","doi":"10.1016/j.orggeochem.2025.104929","DOIUrl":"10.1016/j.orggeochem.2025.104929","url":null,"abstract":"<div><div>The evolution of soil organic carbon (SOC) stocks is critical for both food production and climate change mitigation. This study uses advanced electron paramagnetic resonance (EPR) spectroscopy to investigate the spatial localisation and characterisation of organic carbon in speleothems, with a particular focus on methodological advances in recent decades. A speleothem sample from the Choranche cave in France was analysed using UV laser-induced fluorescence (LIF) and continuous wave EPR spectroscopy. The LIF analysis identified three main types of organic compounds − aromatic amino acids, aliphatic aromatics and larger aromatic compounds − distributed throughout the sample. EPR spectroscopy revealed the presence of Fe³⁺ and Mn²⁺ ions, along the entire sample for Fe³⁺ and more localised for Mn²⁺. When radical organic matter (ROM) is detected, first and second harmonic EPR imaging shows its collocation with Fe³⁺ and Mn²⁺, suggesting specific embedding conditions or source events. The study highlights a significant discrepancy between fluorescent organic matter (FOM) and ROM, challenging previous assumptions about their co-transfer from soil to speleothems. The results suggest that ROM is likely to be associated with specific soil redox conditions or high-energy events, whereas FOM represents a continuous background transfer. This distinction is crucial for accurate interpretations of soil organic carbon loss and its environmental implications. Future research should integrate detailed spectroscopic and isotopic analyses to better quantify organic carbon dynamics and their environmental proxies. Our results highlight the importance of distinguishing between different types of organic matter in speleothems to improve our understanding of soil organic carbon fluxes in relation to climate and human land use.</div></div>","PeriodicalId":400,"journal":{"name":"Organic Geochemistry","volume":"201 ","pages":"Article 104929"},"PeriodicalIF":2.6,"publicationDate":"2025-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143145154","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Geochemistry Articles – October 2024","authors":"","doi":"10.1016/j.orggeochem.2024.104896","DOIUrl":"10.1016/j.orggeochem.2024.104896","url":null,"abstract":"","PeriodicalId":400,"journal":{"name":"Organic Geochemistry","volume":"199 ","pages":"Article 104896"},"PeriodicalIF":2.6,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143104868","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}

{"title":"Geochemistry Articles – September 2024","authors":"","doi":"10.1016/j.orggeochem.2024.104885","DOIUrl":"10.1016/j.orggeochem.2024.104885","url":null,"abstract":"","PeriodicalId":400,"journal":{"name":"Organic Geochemistry","volume":"199 ","pages":"Article 104885"},"PeriodicalIF":2.6,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143104869","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}