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Quantitative salinity reconstructions of the Baltic Sea during the mid-Holocene

Ning, Wenxin LU ; Andersson, Per S.; Ghosh, Anupam LU ; Khan, Mansoor and Filipsson, Helena L. LU (2017) In Boreas 46(1). p.100-110
Abstract

We reconstructed the past coastal environment of the Baltic Sea from c. 7300 to 3500 cal. a BP, with a focus on sea surface salinity (SSS). To quantitatively determine the SSS, two methods were employed: measurements of 87Sr/86Sr ratios in mollusc shells (SSSS r) and process length variations of dinoflagellate cysts Operculodinium centrocarpum (SSSpl). The SSSS r was ~6–7 between 6800 and 6400 cal. a BP, similar to modern conditions. Between 6000 and 3900 cal. a BP, SSSS r was consistently higher, ranging between ~9 and 13. Microfossils sensitive to salinity variations, such as Radiosperma corbiforum and... (More)

We reconstructed the past coastal environment of the Baltic Sea from c. 7300 to 3500 cal. a BP, with a focus on sea surface salinity (SSS). To quantitatively determine the SSS, two methods were employed: measurements of 87Sr/86Sr ratios in mollusc shells (SSSS r) and process length variations of dinoflagellate cysts Operculodinium centrocarpum (SSSpl). The SSSS r was ~6–7 between 6800 and 6400 cal. a BP, similar to modern conditions. Between 6000 and 3900 cal. a BP, SSSS r was consistently higher, ranging between ~9 and 13. Microfossils sensitive to salinity variations, such as Radiosperma corbiforum and Spiniferites spp., support the SSSS r estimate. In comparison with the SSSS r, the SSSpl values were consistently higher, with an average of ~14. We suggest SSSpl tend to overestimate salinity and are not as reliable as SSSSr. A multi-proxy approach, including analysis of microfossil, organic carbon content, C/N ratios and grain-size, allowed for a division of the study period into three zones (Zones I–III). Zone I (7300–6400 cal. a BP) is characterized by relatively O. centrocarpum and R. corbiforum concentrations, silt contents and C/N ratios, corresponding to the regional Littorina transgression maximum. Zone II (6400–3900 cal. a BP) is characterized by increased Spiniferites spp. and decreased R. corbiforum abundances, and by lowered C/N ratios and silt contents relative to Zone I. Zone III (3900–3500 cal. a BP) represents the start of the Post-Littorina Sea phase, indicating a shift to the modern Baltic Sea phase with decreased salinity.

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author
organization
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type
Contribution to journal
publication status
published
subject
in
Boreas
volume
46
issue
1
pages
11 pages
publisher
Taylor & Francis
external identifiers
  • scopus:85006414922
  • wos:000392869300008
ISSN
0300-9483
DOI
10.1111/bor.12156
language
English
LU publication?
yes
id
57f9fbbb-afe8-44d8-a78c-f83d1b19c544
date added to LUP
2017-03-20 13:49:35
date last changed
2017-09-18 11:33:23
@article{57f9fbbb-afe8-44d8-a78c-f83d1b19c544,
  abstract     = {<p>We reconstructed the past coastal environment of the Baltic Sea from c. 7300 to 3500 cal. a BP, with a focus on sea surface salinity (SSS). To quantitatively determine the SSS, two methods were employed: measurements of <sup>87</sup>Sr/<sup>86</sup>Sr ratios in mollusc shells (SSS<sub>S</sub>         <sub>r</sub>) and process length variations of dinoflagellate cysts Operculodinium centrocarpum (SSS<sub>pl</sub>). The SSS<sub>S</sub>         <sub>r</sub> was ~6–7 between 6800 and 6400 cal. a BP, similar to modern conditions. Between 6000 and 3900 cal. a BP, SSS<sub>S</sub>         <sub>r</sub> was consistently higher, ranging between ~9 and 13. Microfossils sensitive to salinity variations, such as Radiosperma corbiforum and Spiniferites spp., support the SSS<sub>S</sub>         <sub>r</sub> estimate. In comparison with the SSS<sub>S</sub>         <sub>r</sub>, the SSS<sub>pl</sub> values were consistently higher, with an average of ~14. We suggest SSSpl tend to overestimate salinity and are not as reliable as SSS<sub>Sr</sub>. A multi-proxy approach, including analysis of microfossil, organic carbon content, C/N ratios and grain-size, allowed for a division of the study period into three zones (Zones I–III). Zone I (7300–6400 cal. a BP) is characterized by relatively O. centrocarpum and R. corbiforum concentrations, silt contents and C/N ratios, corresponding to the regional Littorina transgression maximum. Zone II (6400–3900 cal. a BP) is characterized by increased Spiniferites spp. and decreased R. corbiforum abundances, and by lowered C/N ratios and silt contents relative to Zone I. Zone III (3900–3500 cal. a BP) represents the start of the Post-Littorina Sea phase, indicating a shift to the modern Baltic Sea phase with decreased salinity.</p>},
  author       = {Ning, Wenxin and Andersson, Per S. and Ghosh, Anupam and Khan, Mansoor and Filipsson, Helena L.},
  issn         = {0300-9483},
  language     = {eng},
  month        = {01},
  number       = {1},
  pages        = {100--110},
  publisher    = {Taylor & Francis},
  series       = {Boreas},
  title        = {Quantitative salinity reconstructions of the Baltic Sea during the mid-Holocene},
  url          = {http://dx.doi.org/10.1111/bor.12156},
  volume       = {46},
  year         = {2017},
}