On the relation between organic and inorganic carbon in the Weddell Sea

• Main Authors: Wedborg, M., Hoppema, Mario, Skoog, A.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: 1998
• Subjects: Ice Shelf; Joinville Island; Larsen Ice Shelf; Weddell Sea
• Online Access: https://epic.awi.de/id/eprint/3298/; https://hdl.handle.net/10013/epic.13881

Carbon cycling in the Weddell Sea was investigated during the ANT X/7 cruise with 'FS Polarstern' Dec. 1992 - Jan. 1993. Samples were taken on a cross section from Kapp Norvegia to Joinville Island, and on a section from the Larsen Ice Shelf to the north-east. The following quantities were measured: total carbon dioxide (TCO2), fluorescence from humic substances and total organic carbon. The distribution of TCO2 was strongly positively correlated to the time elapsed since the various water masses were last ventilated. In general, humic substance fluorescence was positively correlated with TCO2, with the exception of the productive part of the western Weddell Sea, where the correlation was negative in the surface mixed layer. The increased fluorescence at the surface is suggested to be a result of biological production. The distribution of total organic carbon showed less structure, since this quantity includes a particulate component, which is subject to dispersion processes different from those of the dissolved components TCO2 and humic substances. The mean total organic carbon concentration below the surface mixed layer was 50 µmol l1. At some stations, a steep maximum around 2000 m depth was observed. This was interpreted to result from mass sinking of phytoplankton blooms. Total organic carbon had a maximum in surface water and, at some stations also a second subsurface maximum. In the Warm Deep Water, TCO2 and fluorescence had their maximum values, while total organic carbon tended to be low. In low productivity surface water in the eastern part of the Kapp Norvegia - Joinville Island section, the lowest fluorescence was found. Surface water is eventually formed from Warm Deep Water, which had the highest fluorescence values, and therefore it is concluded that humic substances were removed in situ from surface water. In the central area of the Weddell Sea, TCO2 and fluorescence showed their highest Warm Deep Water maxima, while total organic carbon was low. The Warm Deep Water in this area, close to the ...