Investigating organic compounds in marine sediments can potentially unlock a wealth of new information in these climate archives. Here we present pilot study results of organic geochemical features of long-chain n-alkanes and alkenones and individual carbon isotope ratios of long-chain n-alkanes from a newly collected, approximately 8-meter long, located in the far reaches of the Pacific sector of the Southern Ocean. We analyzed a suite of organic compounds in the core. The results show abundant long-chain n-alkanes (C29-C35) with predominant odd-over-even carbon preference, suggesting an origin of terrestrial higher plant waxes via long-range transport of dust, possibly from Australia and New Zealand. The δ13C values of the C31 n-alkane range from -29.4 to -24.8‰, in which the higher δ13C values suggest more contributions from C4 plant waxes. In the analysis, we found that the mid-chain n-alkanes (C23-C25) have a small odd-over-even carbon preference, indicating that they were derived from marine non-diatom pelagic phytoplankton and microalgae and terrestrial sources. Furthermore, the C26 and C28 with lower δ13C values (~ -34‰) indicate an origin from marine chemoautotrophic bacteria. We found that the abundances of tetra-unsaturated alkenones (C37:4) in this Southern Ocean sediment core ranges from 11-37%, perhaps a marker of low sea surface temperature (SST). The results of this study strongly indicate that the δ13C values of long-chain n-alkanes and index are potentially useful to reconstruct the detailed history of C3/C4 plants and SST change in the higher latitudes of the Southern Ocean.
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Posted 06 Jan, 2021
Received 14 Feb, 2021
Invitations sent on 03 Jan, 2021
On 03 Jan, 2021
On 20 Dec, 2020
On 20 Dec, 2020
On 20 Dec, 2020
Posted 10 Dec, 2020
On 10 Dec, 2020
On 10 Dec, 2020
On 10 Dec, 2020
Received 06 Oct, 2020
On 06 Oct, 2020
Received 30 Sep, 2020
On 28 Aug, 2020
On 19 Aug, 2020
Invitations sent on 19 Aug, 2020
On 03 Aug, 2020
On 02 Aug, 2020
On 02 Aug, 2020
On 30 Jul, 2020
Posted 06 Jan, 2021
Received 14 Feb, 2021
Invitations sent on 03 Jan, 2021
On 03 Jan, 2021
On 20 Dec, 2020
On 20 Dec, 2020
On 20 Dec, 2020
Posted 10 Dec, 2020
On 10 Dec, 2020
On 10 Dec, 2020
On 10 Dec, 2020
Received 06 Oct, 2020
On 06 Oct, 2020
Received 30 Sep, 2020
On 28 Aug, 2020
On 19 Aug, 2020
Invitations sent on 19 Aug, 2020
On 03 Aug, 2020
On 02 Aug, 2020
On 02 Aug, 2020
On 30 Jul, 2020
Investigating organic compounds in marine sediments can potentially unlock a wealth of new information in these climate archives. Here we present pilot study results of organic geochemical features of long-chain n-alkanes and alkenones and individual carbon isotope ratios of long-chain n-alkanes from a newly collected, approximately 8-meter long, located in the far reaches of the Pacific sector of the Southern Ocean. We analyzed a suite of organic compounds in the core. The results show abundant long-chain n-alkanes (C29-C35) with predominant odd-over-even carbon preference, suggesting an origin of terrestrial higher plant waxes via long-range transport of dust, possibly from Australia and New Zealand. The δ13C values of the C31 n-alkane range from -29.4 to -24.8‰, in which the higher δ13C values suggest more contributions from C4 plant waxes. In the analysis, we found that the mid-chain n-alkanes (C23-C25) have a small odd-over-even carbon preference, indicating that they were derived from marine non-diatom pelagic phytoplankton and microalgae and terrestrial sources. Furthermore, the C26 and C28 with lower δ13C values (~ -34‰) indicate an origin from marine chemoautotrophic bacteria. We found that the abundances of tetra-unsaturated alkenones (C37:4) in this Southern Ocean sediment core ranges from 11-37%, perhaps a marker of low sea surface temperature (SST). The results of this study strongly indicate that the δ13C values of long-chain n-alkanes and index are potentially useful to reconstruct the detailed history of C3/C4 plants and SST change in the higher latitudes of the Southern Ocean.
Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
This preprint is available for download as a PDF.
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