Bulk and compound-specific δ13C and n-alkane indices in a palustrine intermontane record for assessing environmental changes over the past 320 ka: the Padul Basin (Southwestern Mediterranean realm)
Here we provide valuable information about the palaeoenvironmental evolution of Southwestern Mediterranean region during the last ca. 320 ka through a biomarker-based study of the longest continuous continental Quaternary record in the Iberian Peninsula. The n-alkane content and δ13C values of these lipids were measured in 300 samples taken from the uppermost 55 m of the Padul Basin (PB) record. The δ13C signal of long-chain n-alkanes was a reliable proxy for C4/C3 terrestrial vegetation composition in the basin, as emergent macrophytes made a minor contribution to these homologues. In contrast, the δ13C values of C23 and C25 alkanes reflected mainly phases of increasing water level of the lacustrine/palustrine water body since aquatic macrophytes contain a large proportion of these compounds. Low δ13C values were attributed to a marked contribution of plants using the C3 photosynthetic pathway. Intervals with the lowest δ13C values were attributed to an important input of angiosperms, although they could also be explained by changing environmental conditions or environmental stress, as large shifts in δ13C occurred in long-chain homologues typically abundant in terrestrial plants. Shifts in δ13C of medium-chain homologues reflected limited CO2 availability induced by water temperature, salinity, pH, enhanced productivity, low atmospheric pCO2, or stagnant barriers, rather than the abundance of aquatic macrophytes. Our results also suggest enhanced isotopic fractionation during lipid synthesis by aquatic macrophytes within MIS 7 and the Holocene, leading to increased δ13C values of bulk OM and of long-chain n-alkanes. Hence, the δ13C logs were ideal for studying the contribution of aquatic macrophytes to the lipid and isotopic composition of sediments and for the reconstruction of palaeoenvironmental conditions. These results confirmed that C4 plants had a low presence in the PB. Comparison with biomarker analysis and pollen data of the PB and other records of the Southwestern Mediterranean revealed that δ13C values of bulk OM and of long-chain n-alkanes reflected global climatic oscillations during MIS 7 and the episodes Heinrich Events 3, 2, 1 and Younger Dryas.
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Format: | artículo biblioteca |
Language: | English |
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2021-08-02
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Subjects: | n-alkanes, δ13C, Aquatic plants, Terrestrial plants, Padul, Palaeoenvironment, |
Online Access: | http://hdl.handle.net/10261/247539 http://dx.doi.org/10.13039/501100006055 http://dx.doi.org/10.13039/501100000780 |
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dig-ipna-es-10261-2475392022-01-25T11:22:06Z Bulk and compound-specific δ13C and n-alkane indices in a palustrine intermontane record for assessing environmental changes over the past 320 ka: the Padul Basin (Southwestern Mediterranean realm) Ortiz, José E. Torres, Trinidad Delgado Huertas, Antonio Valle, Maruja Soler, Vicente Araujo, Rafael Rivas, María R. Julià, Ramón Sánchez-Palencia, Yolanda Vega-Panizo, Rogelio Consejo de Seguridad Nuclear (España) European Commission Empresa Nacional de Residuos Radiactivos (España) n-alkanes δ13C Aquatic plants Terrestrial plants Padul Palaeoenvironment Here we provide valuable information about the palaeoenvironmental evolution of Southwestern Mediterranean region during the last ca. 320 ka through a biomarker-based study of the longest continuous continental Quaternary record in the Iberian Peninsula. The n-alkane content and δ13C values of these lipids were measured in 300 samples taken from the uppermost 55 m of the Padul Basin (PB) record. The δ13C signal of long-chain n-alkanes was a reliable proxy for C4/C3 terrestrial vegetation composition in the basin, as emergent macrophytes made a minor contribution to these homologues. In contrast, the δ13C values of C23 and C25 alkanes reflected mainly phases of increasing water level of the lacustrine/palustrine water body since aquatic macrophytes contain a large proportion of these compounds. Low δ13C values were attributed to a marked contribution of plants using the C3 photosynthetic pathway. Intervals with the lowest δ13C values were attributed to an important input of angiosperms, although they could also be explained by changing environmental conditions or environmental stress, as large shifts in δ13C occurred in long-chain homologues typically abundant in terrestrial plants. Shifts in δ13C of medium-chain homologues reflected limited CO2 availability induced by water temperature, salinity, pH, enhanced productivity, low atmospheric pCO2, or stagnant barriers, rather than the abundance of aquatic macrophytes. Our results also suggest enhanced isotopic fractionation during lipid synthesis by aquatic macrophytes within MIS 7 and the Holocene, leading to increased δ13C values of bulk OM and of long-chain n-alkanes. Hence, the δ13C logs were ideal for studying the contribution of aquatic macrophytes to the lipid and isotopic composition of sediments and for the reconstruction of palaeoenvironmental conditions. These results confirmed that C4 plants had a low presence in the PB. Comparison with biomarker analysis and pollen data of the PB and other records of the Southwestern Mediterranean revealed that δ13C values of bulk OM and of long-chain n-alkanes reflected global climatic oscillations during MIS 7 and the episodes Heinrich Events 3, 2, 1 and Younger Dryas. Funding was obtained through the projects “Evidence from Quaternary Infills Palaeohydrogeology” (European Union, F14W/CT96/0031), “Evolución Paleoclimática de la Mitad Sur de la Península Ibérica” of ENRESA (National Company for Radioactive Waste Management, 703238) and “Paleoclima” of ENRESA and CSN (Spanish Nuclear Safety Council). We thank one anonymous reviewers for their valuable and helpful comments on the manuscript. Peer reviewed 2021-08-09T08:58:18Z 2021-08-09T08:58:18Z 2021-08-02 artículo http://purl.org/coar/resource_type/c_6501 Journal of Iberian Geology 47: 625–639 (2021) 1698-6180 http://hdl.handle.net/10261/247539 10.1007/s41513-021-00175-y 1886-7995 http://dx.doi.org/10.13039/501100006055 http://dx.doi.org/10.13039/501100000780 en Publisher's version https://doi.org/10.1007/s41513-021-00175-y Sí open Springer |
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n-alkanes δ13C Aquatic plants Terrestrial plants Padul Palaeoenvironment n-alkanes δ13C Aquatic plants Terrestrial plants Padul Palaeoenvironment |
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n-alkanes δ13C Aquatic plants Terrestrial plants Padul Palaeoenvironment n-alkanes δ13C Aquatic plants Terrestrial plants Padul Palaeoenvironment Ortiz, José E. Torres, Trinidad Delgado Huertas, Antonio Valle, Maruja Soler, Vicente Araujo, Rafael Rivas, María R. Julià, Ramón Sánchez-Palencia, Yolanda Vega-Panizo, Rogelio Bulk and compound-specific δ13C and n-alkane indices in a palustrine intermontane record for assessing environmental changes over the past 320 ka: the Padul Basin (Southwestern Mediterranean realm) |
description |
Here we provide valuable information about the palaeoenvironmental evolution of Southwestern Mediterranean region during the last ca. 320 ka through a biomarker-based study of the longest continuous continental Quaternary record in the Iberian Peninsula. The n-alkane content and δ13C values of these lipids were measured in 300 samples taken from the uppermost 55 m of the Padul Basin (PB) record. The δ13C signal of long-chain n-alkanes was a reliable proxy for C4/C3 terrestrial vegetation composition in the basin, as emergent macrophytes made a minor contribution to these homologues. In contrast, the δ13C values of C23 and C25 alkanes reflected mainly phases of increasing water level of the lacustrine/palustrine water body since aquatic macrophytes contain a large proportion of these compounds. Low δ13C values were attributed to a marked contribution of plants using the C3 photosynthetic pathway. Intervals with the lowest δ13C values were attributed to an important input of angiosperms, although they could also be explained by changing environmental conditions or environmental stress, as large shifts in δ13C occurred in long-chain homologues typically abundant in terrestrial plants. Shifts in δ13C of medium-chain homologues reflected limited CO2 availability induced by water temperature, salinity, pH, enhanced productivity, low atmospheric pCO2, or stagnant barriers, rather than the abundance of aquatic macrophytes. Our results also suggest enhanced isotopic fractionation during lipid synthesis by aquatic macrophytes within MIS 7 and the Holocene, leading to increased δ13C values of bulk OM and of long-chain n-alkanes. Hence, the δ13C logs were ideal for studying the contribution of aquatic macrophytes to the lipid and isotopic composition of sediments and for the reconstruction of palaeoenvironmental conditions. These results confirmed that C4 plants had a low presence in the PB. Comparison with biomarker analysis and pollen data of the PB and other records of the Southwestern Mediterranean revealed that δ13C values of bulk OM and of long-chain n-alkanes reflected global climatic oscillations during MIS 7 and the episodes Heinrich Events 3, 2, 1 and Younger Dryas. |
author2 |
Consejo de Seguridad Nuclear (España) |
author_facet |
Consejo de Seguridad Nuclear (España) Ortiz, José E. Torres, Trinidad Delgado Huertas, Antonio Valle, Maruja Soler, Vicente Araujo, Rafael Rivas, María R. Julià, Ramón Sánchez-Palencia, Yolanda Vega-Panizo, Rogelio |
format |
artículo |
topic_facet |
n-alkanes δ13C Aquatic plants Terrestrial plants Padul Palaeoenvironment |
author |
Ortiz, José E. Torres, Trinidad Delgado Huertas, Antonio Valle, Maruja Soler, Vicente Araujo, Rafael Rivas, María R. Julià, Ramón Sánchez-Palencia, Yolanda Vega-Panizo, Rogelio |
author_sort |
Ortiz, José E. |
title |
Bulk and compound-specific δ13C and n-alkane indices in a palustrine intermontane record for assessing environmental changes over the past 320 ka: the Padul Basin (Southwestern Mediterranean realm) |
title_short |
Bulk and compound-specific δ13C and n-alkane indices in a palustrine intermontane record for assessing environmental changes over the past 320 ka: the Padul Basin (Southwestern Mediterranean realm) |
title_full |
Bulk and compound-specific δ13C and n-alkane indices in a palustrine intermontane record for assessing environmental changes over the past 320 ka: the Padul Basin (Southwestern Mediterranean realm) |
title_fullStr |
Bulk and compound-specific δ13C and n-alkane indices in a palustrine intermontane record for assessing environmental changes over the past 320 ka: the Padul Basin (Southwestern Mediterranean realm) |
title_full_unstemmed |
Bulk and compound-specific δ13C and n-alkane indices in a palustrine intermontane record for assessing environmental changes over the past 320 ka: the Padul Basin (Southwestern Mediterranean realm) |
title_sort |
bulk and compound-specific δ13c and n-alkane indices in a palustrine intermontane record for assessing environmental changes over the past 320 ka: the padul basin (southwestern mediterranean realm) |
publisher |
Springer |
publishDate |
2021-08-02 |
url |
http://hdl.handle.net/10261/247539 http://dx.doi.org/10.13039/501100006055 http://dx.doi.org/10.13039/501100000780 |
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