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Late Holocene freshening of the Baltic Sea derived from high-resolution strontium isotope analyses of mollusk shells

Anders Widerlund and Per S. Andersson
Late Holocene freshening of the Baltic Sea derived from high-resolution strontium isotope analyses of mollusk shells
Geology (Boulder) (February 2011) 39 (2): 187-190

Abstract

Strontium isotopic composition ( (super 87) Sr/ (super 86) Sr) data from subfossil (super 14) C-dated mollusk shells in raised beach sediments are used as a paleosalinity proxy in the brackish Baltic Sea, the precision (+ or -5%) and accuracy (+ or -0.7 per mil) of the method being judged from replicate analyses of modern shells. Paleosalinity data with an average time resolution of approximately 200 yr for the period 7130-2775 calibrated (super 14) C yr B.P. indicate maximum surface salinities of 10 per mil-11 per mil, 11 per mil-12 per mil, and 12 per mil-13 per mil for the Bothnian Bay, Bothnian Sea, and Baltic Proper (the three major Baltic subbasins). The relative salinity differences between the basins were small (< or =30%) compared to the as much as eightfold present-day relative salinity differences (Bothnian Bay 1 per mil-3 per mil; Bothnian Sea 4 per mil-5 per mil; Baltic Proper 6 per mil-8 per mil). Late Holocene freshening (ca. 3000 calibrated (super 14) C yr B.P. to present) is most pronounced in the northernmost subbasin, the Bothnian Bay, consistent with the absence of a permanent halocline, sequestering of phosphorus in well-oxygenated bottom sediments, and phosphorus limitation of primary production in the present-day Bothnian Bay. This study suggests that paleosalinity data may be crucial to improving our understanding of the possible effects of any future, climate-induced freshening of the Baltic Sea.


ISSN: 0091-7613
EISSN: 1943-2682
Coden: GLGYBA
Serial Title: Geology (Boulder)
Serial Volume: 39
Serial Issue: 2
Title: Late Holocene freshening of the Baltic Sea derived from high-resolution strontium isotope analyses of mollusk shells
Affiliation: Lulea University of Technology, Division of Geosciences, Lulea, Sweden
Pages: 187-190
Published: 201102
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 26
Accession Number: 2011-019911
Categories: Quaternary geologyIsotope geochemistry
Document Type: Serial
Bibliographic Level: Analytic
Annotation: With GSA Data Repository Item 2011075
Illustration Description: illus. incl. sketch map
N54°00'00" - N66°00'00", E10°00'00" - E30°00'00"
Secondary Affiliation: Swedish Museum of Natural History, SWE, Sweden
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 201112
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