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Helena Filipsson, foto Erik Thor

Helena Filipsson

Professor

Helena Filipsson, foto Erik Thor

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

Author

  • Wenxin Ning
  • Per S. Andersson
  • Anupam Ghosh
  • Mansoor Khan
  • Helena L. Filipsson

Summary, in English

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.

Department/s

  • Department of Geology
  • BECC: Biodiversity and Ecosystem services in a Changing Climate

Publishing year

2017-01-01

Language

English

Pages

100-110

Publication/Series

Boreas

Volume

46

Issue

1

Document type

Journal article

Publisher

John Wiley & Sons Inc.

Topic

  • Oceanography, Hydrology, Water Resources

Status

Published

ISBN/ISSN/Other

  • ISSN: 0300-9483