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| Titel |
Growth phase dependent hydrogen isotopic fractionation in alkenone-producing haptophytes |
| VerfasserIn |
M. D. Wolhowe, F. G. Prahl, I. Probert, M. Maldonado |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 6, no. 8 ; Nr. 6, no. 8 (2009-08-19), S.1681-1694 |
| Datensatznummer |
250003956
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| Publikation (Nr.) |
 copernicus.org/bg-6-1681-2009.pdf |
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| Zusammenfassung |
| Recent works have investigated use of the hydrogen isotopic composition of
C37 alkenones (δDK37s, lipid biomarkers of certain
haptophyte microalgae, as an independent paleosalinity proxy. We discuss
herein the factors impeding the success of such an application and identify
the potential alternative use of δDK37s measurements as a proxy
for non-thermal, physiological stress impacts on the U37K'
paleotemperature index. Batch-culture experiments with the haptophyte
Emiliania huxleyi (CCMP 1742) were conducted to determine the magnitude and variability of
the isotopic contrasts between individual C37 alkenones. Further
experiments were conducted with Emiliania huxleyi (CCMP 1742) andGephyrocapsa oceanica (PZ3-1) to determine
whether, and to what extent, δDK37s varies between the
physiological extremes of nutrient-replete exponential growth and
nutrient-depleted senescence. Emiliania huxleyi was observed to exhibit an isotopic contrast
between di- and tri-unsaturated C37 alkenones (αK37:3-K37:2≈0.97) that is nearly identical to that reported
recently by others for environmental samples. Furthermore, this contrast
appears to be constant with growth stage. The consistency of the offset
across different growth stages suggests that a single, well-defined value
for αK37:3-K37:2 may exist and that its use in an isotope
mass-balance will allow accurate determination of δD values for
individual alkenones without having to rely on time- and labor-intensive
chemical separations. The isotopic fractionation between growth medium and
C37 alkenones was observed to increase dramatically upon the onset of
nutrient-depletion-induced senescence, suggesting that δDK37s
may serve as an objective tool for recognizing and potentially correcting,
at least semi-quantitatively, for the effects of nutrient stress on
U37K' temperature records. |
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