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| Titel |
Large spatial variations in coastal 14C reservoir age – a case study from the Baltic Sea |
| VerfasserIn |
B. C. Lougheed, H. L. Filipsson, I. Snowball |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1814-9324
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| Digitales Dokument |
URL |
| Erschienen |
In: Climate of the Past ; 9, no. 3 ; Nr. 9, no. 3 (2013-05-07), S.1015-1028 |
| Datensatznummer |
250018051
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| Publikation (Nr.) |
 copernicus.org/cp-9-1015-2013.pdf |
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| Zusammenfassung |
| Coastal locations are highly influenced by input from freshwater river
runoff, including sources of terrestrial carbon, which can be expected to
modify the 14C reservoir age, or R (t), associated with marine water.
In this Baltic Sea case study, pre-bomb museum collection mollusc shells of
known calendar age, from 30 locations across a strategic salinity transect of
the Baltic Sea, were analysed for 14C, δ13C and δ18O.
R (t) was calculated for all 30 locations. Seven locations, of
which six are within close proximity of the coast, were found to have
relatively higher R (t) values, indicative of hard-water effects. Whenever
possible, the Macoma genus of mollusc was selected from the museum
collections, in order to exclude species specific reservoir age effects as
much as possible. When the Macoma samples are exclusively
considered, and samples from hard-water locations excluded, a statistically
significant correlation between Macoma R (t) and average salinity
is found, indicating a two end-member linear mixing model between
14Cmarine and 14Crunoff. A map of Baltic Sea
Macoma aragonite R (t) for the late 19th and early 20th centuries
is produced. Such a map can provide an estimate for contemporary Baltic Sea
Macoma R (t), although one must exercise caution when applying such
estimates back in time or to 14C dates obtained from different sample
material. A statistically significant correlation is found between δ18Oaragonite
and Macoma R (t), suggesting that
δ18Oaragonite can be used to estimate Macoma
palaeo-R (t), due to the δ18Oaragonite signal being
dominated by the salinity gradient of the Baltic Sea. A slightly increased
correlation can be expected when δ18Oaragonite is
corrected for temperature fractionation effects. The results of this Baltic
Sea case study, which show that R (t) is affected by hydrographic conditions
and local carbon inputs, have important consequences for other coastal and
estuarine locations, where R (t) is also likely to significantly vary on
spatial and temporal bases. |
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