{"refrec":{"BRefID":437427,"RR":"<b>Nierop, K.G.J.; Mijs, M.; Dekker, R.; Lewan, M.D.; Speelman, E.N.; de Leeuw, J.W.; Reichart, G.-J.</b> (2025). Thermal stability of freshwater fern Azolla biomarkers as assessed by hydrous pyrolysis. <i>Org. Geochem. 205</i>: 105008. <a href=\"https://dx.doi.org/10.1016/j.orggeochem.2025.105008\" target=\"_blank\">https://dx.doi.org/10.1016/j.orggeochem.2025.105008</a>","BEntID":435258,"PublicFlag":1,"CheckedFlag":0,"wosflag":1,"vabbflag":0,"RefStringPartII":". <i>Org. Geochem. 205</i>: 105008. <a href=\"https://dx.doi.org/10.1016/j.orggeochem.2025.105008\" target=\"_blank\">https://dx.doi.org/10.1016/j.orggeochem.2025.105008</a>","DocTypID":8,"DocType":"Journal article","MarineFlag":0,"FreshFlag":0,"BrackishFlag":0,"TerrestrialFlag":0,"Authorstring":"Nierop, K.G.J.; Mijs, M.; Dekker, R.; Lewan, M.D.; Speelman, E.N.; de Leeuw, J.W.; Reichart, G.-J.","OrigTitleTranslFlag":0,"Authorstringtrunc":"Nierop, K.G.J. <i>et al.</i>","Englishabstract":"<span style=\"color:rgb(31,31,31);\">The freshwater fern </span><i>Azolla</i><span style=\"color:rgb(31,31,31);\"> produces a unique series of ω20-hydroxy and ω9,ω10-dihydroxy lipids. These compounds were also detected in Eocene sediments (∼48.5&nbsp;Ma) characterized by the occurrence of fossil remains of </span><i>Azolla</i><span style=\"color:rgb(31,31,31);\"> and are thought to be prime markers for the past occurrence of </span><i>Azolla</i><span style=\"color:rgb(31,31,31);\"> implying that they could serve as palaeo-environmental indicators of freshwater conditions. However, the suitability of these </span><i>Azolla</i><span style=\"color:rgb(31,31,31);\"> biomarkers for application to more mature sediments is unknown. In this study, </span><i>Azolla caroliniana</i><span style=\"color:rgb(31,31,31);\"> specimens were heated using hydrous pyrolysis at temperatures ranging from 220 to 365&nbsp;°C for 72&nbsp;h to examine the stability and degradation of the </span><i>Azolla</i><span style=\"color:rgb(31,31,31);\"> biomarkers during simulated diagenesis. Initially all ω20-hydroxy and ω9,ω10-dihydroxy lipids are converted to their ketone analogues. At 260&nbsp;°C </span><i>n</i><span style=\"color:rgb(31,31,31);\">-alkanes are formed. ω20-Hydroxy and ω9,ω10-dihydroxy lipids are degraded between 260 and 280&nbsp;°C. At 300&nbsp;°C, only ω20-keto-1-ols, ω20-keto fatty acids and ω20-ketones, along with their ω9 and ω10 analogues, remain to preserve their ω20, ω9 and ω10 functionalities, while at 320&nbsp;°C and higher only the ω20-, ω9, and ω10-ketones were observed. At higher temperatures the proportions of </span><i>n</i><span style=\"color:rgb(31,31,31);\">-alkanes became dominating. The high thermal stability of the ω20, ω9/ω10 functionality shows that it has a relatively high preservation potential. Hence, it may potentially be a robust source indicator of the depositional environment of </span><i>Azolla</i><span style=\"color:rgb(31,31,31);\">-derived organic carbon reflecting freshwater or brackish surface waters.</span>","AbstractOtherLang":null,"BibLvlCode":"AS","StandardTitle":"Thermal stability of freshwater fern Azolla biomarkers as assessed by hydrous pyrolysis","OrigTitleLangCode":"en","OrigTitleLangCodeExtended":"eng","OrigTitleLangID":15,"DateLastModified":{"date":"2026-06-10 01:33:05.231062","timezone_type":1,"timezone":"+02:00"},"UserAccessRight":null,"UserAccID":null,"AuthorKeywords":"<p style=\"margin-left:0px;\"><i>Azolla; </i>Hydrous pyrolysis; ?20-hydroxy and ?9; ?10-dihydroxy lipids; Biomarker stability","OtherDescriptors":null,"Notes":null,"AnaPub":2025,"MonPub":null,"DateUpdate":"2026-01-28","DateCreate":"2026-01-28","SecASFANote":null,"ConfID":null,"PeerRev":1,"VlizCoreFlag":1,"WoScode":null,"VABBcode":null,"OpenAcc":1,"DOI":"10.1016/j.orggeochem.2025.105008"},"refs":null,"anarec":{"AnaID":437427,"PubliDate":2025,"Pagination":"105008","XtraPublOfAnaID":null,"ISBN":null,"Volume":"205","Issue":null,"BRefMon":null,"BRefMonRR":null,"BRefXtra":null,"BRefXtraRR":null,"SerBRefID":111331,"SerRR":"Organic Geochemistry. 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