THE DISTRIBUTION OF C-14 AND AR-39 IN THE WEDDELL SEA

Citation
P. Schlosser et al., THE DISTRIBUTION OF C-14 AND AR-39 IN THE WEDDELL SEA, J GEO RES-O, 99(C5), 1994, pp. 10275-10287
Citations number
30
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Oceanografhy
Journal title
JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS
ISSN journal
2169-9275 → ACNP
Volume
99
Issue
C5
Year of publication
1994
Pages
10275 - 10287
Database
ISI
SICI code
2169-9275(1994)99:C5<10275:TDOCAA>2.0.ZU;2-V
Abstract
Carbon 14 and Ar-39 data from the Weddell Sea are presented and discus sed. Values of DELTA C-14 and Ar-39 are low in the winter mixed layer (DELTA C-14 almost-equal-to -90 to -125 parts per thousand; Ar-39 almo st-equal-to 85% modern). These low values are consistent with the surf ace layer dynamics which is dominated by entrainment of relatively old water of circumpolar origin and reduced gas exchange during sea ice c over. The DELTA C-14 and Ar-39 values of the deep and bottom waters ra nge from -160 to -150 parts per thousand and 38 to 57% modern, respect ively. The DELTA C-14 values of Weddell Sea Bottom Water (WSBW) found in the central Weddell Sea along a 0-degrees longitude section are onl y slightly higher than those of the overlying Weddell Sea Deep Water ( WSDW) showing that the influence of bomb C-14 on these waters is small . Part of the WSBW with higher DELTA C-14 values observed in the north western Weddell Sea seems to escape through the South Sandwich Trench, and part seems to mix from a boundary current into the central Weddel l Sea. The observed C-14 distribution is consistent with the hypothesi s that Ice Shelf Water (ISW) is a source of WSBW. A simple conceptual model of the surface layer dynamics is used to estimate the prebomb DE LTA C-14 values of Surface Water and Winter Water to be about -140 and -130 parts per thousand, respectively. Using mixing ratios between WS DW and shelf water derived from temperature/salinity arid He-3 data, t he prebomb DELTA C-14 values of WSBW are estimated to be -157 parts pe r thousand (potential temperature of WSBW: -0.7-degrees-C). The Ar-39 concentration of WSBW with a potential temperature of -0.7-degrees-C i s determined to be 57% modern. Bomb radiocarbon water column inventori es are estimated and discussed.