Carbon isotope records from extant Caribbean and South Pacific sponges: Evolution of δ13C in surface water DIC

Beitrag in einer Fachzeitschrift

Details zur Publikation

Autorinnen und Autoren: Joachimski M
Zeitschrift: Earth and Planetary Science Letters
Verlag: Elsevier
Jahr der Veröffentlichung: 1996
Band: 139
Seitenbereich: 291-303
ISSN: 0012-821X


Stable isotope records of demosponges from the Caribbean and Coral Sea are described for the purpose of studying the influence of fossil fuel CO on the carbon isotopic composition of dissolved inorganic carbon (DIC) in surface water. The slow-growing sponges precipitate calcium carbonate in isotopic equilibrium with ambient sea water and are used to detect changes in δC from pre-industrial times (early 19th century) to the present. We observed similar shapes and ranges in δC curves measured on Caribbean specimens collected from water depths of 25, 84 and 91 m as well as a specimen collected in shallow waters off New Caledonia. The records reveal a highly significant correlation with atmospheric δC. δC values for Caribbean and Coral Sea surface waters were calculated using the δC sponge records. While δC of atmospheric CO decreased by about 1.4‰ from the early 19th century to 1990, δC of Caribbean and Coral Sea surface waters decreased by 0.9 ± 0.2‰ and 0.7 ± 0.3‰, respectively. No isotopic equilibrium between surface water DIC and atmospheric CO was observed, either during the pre-industrial steady state or during the last 100 years. The lower amount of depletion in the surface water δC with respect to the atmospheric anthropogenic signal is explained by the dilution of the surface waters by biologically altered subsurface water DIC. The lower δC decrease in the Coral Sea points to a stronger influence of the subsurface water source compared to the Caribbean.

FAU-Autorinnen und Autoren / FAU-Herausgeberinnen und Herausgeber

Joachimski, Michael Prof. Dr.
Lehrstuhl für Geologie (Exogene Dynamik)

Zuletzt aktualisiert 2018-29-12 um 13:50