Effects of alkalinity and salinity at low and high light intensity on hydrogen isotope fractionation of long-chain alkenones produced by <i>Emiliania huxleyi</i>
Over the last decade, hydrogen isotopes of long-chain alkenones have been shown to be a promising proxy for reconstructing paleo sea surface salinity due to a strong hydrogen isotope fractionation response to salinity across different environmental conditions. However, to date, the decoupling of...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2017-12-01
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| Series: | Biogeosciences |
| Online Access: | https://www.biogeosciences.net/14/5693/2017/bg-14-5693-2017.pdf |
| Summary: | Over the last decade, hydrogen isotopes of long-chain alkenones have been
shown to be a promising proxy for reconstructing paleo sea surface salinity
due to a strong hydrogen isotope fractionation response to salinity across
different environmental conditions. However, to date, the decoupling of the
effects of alkalinity and salinity, parameters that co-vary in the surface
ocean, on hydrogen isotope fractionation of alkenones has not been assessed.
Furthermore, as the alkenone-producing haptophyte, <i>Emiliania
huxleyi</i>, is known to grow in large blooms under high light intensities, the
effect of salinity on hydrogen isotope fractionation under these high
irradiances is important to constrain before using <i>δ</i>D<sub>C<sub>37</sub></sub>
to reconstruct paleosalinity. Batch cultures of the marine haptophyte
<i>E. huxleyi</i> strain CCMP 1516 were grown to investigate the hydrogen
isotope fractionation response to salinity at high light intensity and
independently assess the effects of salinity and alkalinity under low-light
conditions. Our results suggest that alkalinity does not significantly
influence hydrogen isotope fractionation of alkenones, but salinity does have
a strong effect. Additionally, no significant difference was observed between
the fractionation responses to salinity recorded in alkenones grown under
both high- and low-light conditions. Comparison with previous studies suggests
that the fractionation response to salinity in culture is similar under
different environmental conditions, strengthening the use of hydrogen isotope
fractionation as a paleosalinity proxy. |
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| ISSN: | 1726-4170 1726-4189 |