New insights into Holocene hydrology and temperature from lipid biomarkers in western Mediterranean alpine wetlands

Toney, J. L. , García-Alix, A. , Jiménez-Moreno, G., Anderson, R. S., Moossen, H. and Seki, O. (2020) New insights into Holocene hydrology and temperature from lipid biomarkers in western Mediterranean alpine wetlands. Quaternary Science Reviews, 240, 106395. (doi: 10.1016/j.quascirev.2020.106395)

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Abstract

Alpine regions of the Mediterranean realm are among the most climatically sensitive areas in the world. Thus, alpine wetlands from the southern Iberian Peninsula, in the westernmost part of the Mediterranean region, are highly sensitive sensors of environmental changes. Difficulties have surfaced in separating controls by temperature and/or precipitation in previous paleoenvironmental studies from alpine environments in this area. We present a Holocene biomarker record (n-alkanes and long-chain diols) from a high elevation lake, Laguna de Río Seco (LdRS), in the south of the Iberian Peninsula, which contributes to the identification of these forcing mechanisms. The hydrological history of the area, primarily water availability and evapotranspiration, is reconstructed by means of the n-alkane record, including the indices of average chain length, portion aquatic, and carbon preference index, as well as hydrogen isotopes (δD) of aquatic (δDaq) and terrestrial (δDwax) n-alkanes. Temperatures are also estimated using the algae derived long-chain diols. We interpret δDaq and δDwax fluctuations as showing changes in the source and amount of precipitation throughout the LdRS record. An Atlantic precipitation source appears to have predominated during the early-middle Holocene, but an occasional Mediterranean influence with an isotopic enrichment in precipitation is detected in the middle-late Holocene that is likely related to the setting of the current atmospheric pattern in southeastern Iberia under the joint control of the North Atlantic Oscillation (NAO) and the Western Mediterranean dynamics, such as the Western Mediterranean Oscillation (WeMO). Our new record from LdRS is consistent with a generalized trend of a humid early-middle Holocene with low temperature variability, evolving towards an arid middle-late Holocene with abrupt temperature changes. In addition to these long-term trends during the last ∼10,500 years, two phases of climate instability, evidenced by abrupt depletions in δDaq, have been identified at the end of these periods, one between ∼6500 and 5500 cal yr BP and another in the last ∼500 years. These episodes would represent strengthened winter cold conditions that favoured the persistence of snowpack and frozen soil in the catchment, causing reduced terrestrial plant growth and low lake evaporation. According to the long-chain diol record, temperatures during these phases were relatively low, but experienced abrupt increases at the end of each period.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Garcia-Alix Daroca, Dr Antonio and Toney, Professor Jaime
Authors: Toney, J. L., García-Alix, A., Jiménez-Moreno, G., Anderson, R. S., Moossen, H., and Seki, O.
College/School:College of Science and Engineering > School of Geographical and Earth Sciences
Journal Name:Quaternary Science Reviews
Publisher:Elsevier
ISSN:0277-3791
ISSN (Online):1873-457X
Published Online:15 June 2020
Copyright Holders:Copyright © 2020 Elsevier Ltd.
First Published:First published in Quaternary Science Reviews 240: 106395
Publisher Policy:Reproduced in accordance with the publisher copyright policy
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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
169953NAOSIPUK: Natural responses to past North Atlantic Oscillations: Southern Iberian Peninsula vs. United Kingdom. Analogues for future environmental changesJaime ToneyEuropean Commission (EC)623027GES - Earth Sciences
168220Gauging North Atlantic climate change through palaeoclimate lake recordsJaime ToneyThe Carnegie Trust for the Universities of Scotland (CARNEGTR)UNSPECIFIEDGES - Earth Sciences