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oai:docta.ucm.es:20.500.14352/235492025-03-13T16:34:22Zcom_20.500.14352_14col_20.500.14352_15

Lipid biomarkers in Lake Enol (Asturias, Northern Spain): Coupled natural and human induced environmental history Ortiz, José E. Sánchez-Palencia, Yolanda Torres, Trinidad Domingo, Laura Mata, M. Pilar Vegas, Juana Sánchez España, Javier Morellón Marteles, Mario Blanco, Lorena 550.47 n-Alkanes n-Alkanoic acids Sterols 24-Ethylcoprostanol Palaeoenvironment Lake Enol Northern Spain Geoquímica 2503 Geoquímica The lipid content of three cores from Lake Enol (Picos de Europa National Park, Asturias, Northern Spain) was studied. The n-alkane profiles indicated a major input from terrigenous plants [predominance of high molecular weight (HMW) alkanes] since ca. 1695 AD to the water body, although the uppermost cm revealed a predominance of organic matter (OM) derived from algae, as the most abundant alkane was C17. Three units revealing different environmental conditions were defined. Unit A (ca. 1695–1860 AD) in the lowermost parts of ENO13-10 (< 12 cm) and ENO13-15 (< 28 cm) was identified and was characterized by higher OM input and evidence of minimal degradation (high CPI values, predominance of HMW n-alkanoic acids and good correspondence between the predominant n-alkane and n-alkanoic acid chains). These findings could be linked to the Little Ice Age, when cold and humid conditions may have favored an increase in total organic carbon (TOC) and n-alkane and n-alkanoic acid content (greater terrigenous OM in-wash), and may have also reduced bacterial activity. In Unit B (ca. 1860–1980 AD) the lack of correspondence between the n-alkane and n-alkanoic acid profiles of ENO13-10 (12–4 cm) and ENO13-15 (28–8 cm) suggested a certain preferential microbial synthesis of long chain saturated fatty acids from primary OM and/or bacterial activity, coinciding with a decrease in OM input, which could be linked to the global warming that started in the second half of the 19th century. In ENO13-7 the low OM input (low TOC) was accompanied by some bacterial degradation (predominance of HMW n-alkanoic acids but with a bimodal distribution) in the lowermost 16–5 cm. Evidence of considerable phytoplankton productivity and microbial activity was especially significant in Unit C (ca. 1980–2013 AD) identified in the uppermost part of all three cores (5 cm in ENO13-7, 4 cm in ENO13-10 and 8 cm in ENO13-15), coinciding with higher concentrations of n-alkanes and n-alkanoic acids, which were considered to be linked to warmer and drier conditions, as well as to greater anthropogenic influence in modern times. Plant sterols, such as b-sitosterol, campesterol and stigmasterol, were significantly present in the cores. In addition, fecal stanols, such as 24-ethylcoprostanol from herbivores, were present, thereby indicating a continuous and significant pollution input derived from these animals since the 17th century, being more important in the last 20 years. Organismo Autónomo de Parques Nacionales (OAPN) Depto. de Geodinámica, Estratigrafía y Paleontología Fac. de Ciencias Geológicas TRUE pub 2023-06-18T05:53:35Z 2023-06-18T05:53:35Z 2016-02 journal article https://hdl.handle.net/20.500.14352/23549 0146-6380 10.1016/j.orggeochem.2015.12.005 eng 533S/2012 Project CLAM 727/2012 restricted access application/pdf Elsevier