Experimental determination of the temperature dependence of oxygen-isotope fractionation between water and chitinous head capsules of chironomid larvae



Lombino, Alex, Atkinson, Tim, Brooks, Stephen J, Grocke, Darren R, Holmes, Jonathan, Jones, Vivienne J and Marshall, Jim D
(2021) Experimental determination of the temperature dependence of oxygen-isotope fractionation between water and chitinous head capsules of chironomid larvae. JOURNAL OF PALEOLIMNOLOGY, 66 (2). pp. 117-124.

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Abstract

<jats:title>Abstract</jats:title><jats:p>Oxygen-isotope values of invertebrate cuticle preserved in lake sediments have been used in palaeoenvironmental reconstructions, generally with the assumption that fractionation of oxygen isotopes between cuticle and water (<jats:inline-formula><jats:alternatives><jats:tex-math>$$\upalpha_{\text{cuticle}-\text{H}_{2}\text{O}}$$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>α</mml:mi> <mml:mrow> <mml:mtext>cuticle</mml:mtext> <mml:mo>-</mml:mo> <mml:msub> <mml:mtext>H</mml:mtext> <mml:mn>2</mml:mn> </mml:msub> <mml:mtext>O</mml:mtext> </mml:mrow> </mml:msub> </mml:math></jats:alternatives></jats:inline-formula>) is independent of temperature. We cultured chironomid larvae in the laboratory with labelled oxygen-isotope water and across a range of closely controlled temperatures from 5 to 25 °C in order to test the hypothesis that fractionation of oxygen isotopes between chironomid head capsules and water (<jats:inline-formula><jats:alternatives><jats:tex-math>$$\upalpha_{\text{chironomid}-\text{H}_{2}\text{O}}$$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>α</mml:mi> <mml:mrow> <mml:mtext>chironomid</mml:mtext> <mml:mo>-</mml:mo> <mml:msub> <mml:mtext>H</mml:mtext> <mml:mn>2</mml:mn> </mml:msub> <mml:mtext>O</mml:mtext> </mml:mrow> </mml:msub> </mml:math></jats:alternatives></jats:inline-formula>) is independent of temperature. Results indicate that the hypothesis can be rejected, and that <jats:inline-formula><jats:alternatives><jats:tex-math>$$\upalpha_{\text{chironomid}-\text{H}_{2}\text{O}}$$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>α</mml:mi> <mml:mrow> <mml:mtext>chironomid</mml:mtext> <mml:mo>-</mml:mo> <mml:msub> <mml:mtext>H</mml:mtext> <mml:mn>2</mml:mn> </mml:msub> <mml:mtext>O</mml:mtext> </mml:mrow> </mml:msub> </mml:math></jats:alternatives></jats:inline-formula> decreases with increasing temperature. The scatter in the data suggests that further experiments are needed to verify the relationship. However, these results indicate that temperature-dependence of <jats:inline-formula><jats:alternatives><jats:tex-math>$$\upalpha_{\text{chironomid}-\text{H}_{2}\text{O}}$$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>α</mml:mi> <mml:mrow> <mml:mtext>chironomid</mml:mtext> <mml:mo>-</mml:mo> <mml:msub> <mml:mtext>H</mml:mtext> <mml:mn>2</mml:mn> </mml:msub> <mml:mtext>O</mml:mtext> </mml:mrow> </mml:msub> </mml:math></jats:alternatives></jats:inline-formula> should be considered when chironomid δ<jats:sup>18</jats:sup>O is used as a paleoenvironmental proxy, especially in cases where data from chironomids are combined with oxygen-isotope values from other materials for which fractionation is temperature dependent, such as calcite, in order to derive reconstructions of past water temperature.</jats:p>

Item Type: Article
Uncontrolled Keywords: Oxygen isotopes, Chironomids, Temperature-dependent isotope fractionation, Palaeoenvironments, Limnology
Divisions: Faculty of Science and Engineering > School of Environmental Sciences
Depositing User: Symplectic Admin
Date Deposited: 06 Sep 2021 07:41
Last Modified: 24 Jan 2023 17:18
DOI: 10.1007/s10933-021-00191-z
Open Access URL: https://doi.org/10.1007/s10933-021-00191-z
Related URLs:
URI: https://livrepository.liverpool.ac.uk/id/eprint/3136051