 |
| Titel |
A novel salinity proxy based on Na incorporation into foraminiferal calcite |
| VerfasserIn |
J. C. Wit, L. J. Nooijer, M. Wolthers, G. J. Reichart |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1726-4170
|
| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 10, no. 10 ; Nr. 10, no. 10 (2013-10-09), S.6375-6387 |
| Datensatznummer |
250085355
|
| Publikation (Nr.) |
 copernicus.org/bg-10-6375-2013.pdf |
|
|
|
|
|
| Zusammenfassung |
| Salinity and temperature determine seawater density, and differences in both
thereby control global thermohaline circulation. Whereas numerous proxies have
been calibrated and applied to reconstruct temperature, a direct and
independent proxy for salinity is still missing. Ideally, a new proxy for
salinity should target one of the direct constituents of dissolved salt, such
as [Na+] or [Cl−]. This study investigates the impact of salinity
on foraminiferal Na/Ca values by laser ablation ICP-MS analyses of
specimens of the benthic foraminifer Ammonia tepida cultured at a
range of salinities (30.0–38.6).
Foraminifera at lower salinities (30.0 and 32.5) added more chambers (10–11)
to their test over the course of the culturing experiment than those
maintained at higher salinities (36.1, 7–8 chambers, and 38.6, 6–7
chambers), suggesting that growth rates in this species are promoted by lower
salinities. The Na/Ca of cultured specimens correlates significantly with
seawater salinity (Na/Ca = 0.22S–0.75, R2 = 0.96,
p < 0.01) and size. Values for Na/Ca and DNa vary
between 5.17 and 9.29 mmol mol−1 and 0.12–0.16 × 10−3,
which are similar to values from inorganic precipitation experiments. The
significant correlation between test size and Na/Ca results from
co-variation with salinity. This implies that foraminiferal Na/Ca could
serve as a robust and independent proxy for salinity, enabling salinity
reconstructions independent of calcitic δ18O. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|