 |
| Titel |
Influence of intense scavenging on Pa-Th fractionation in the wake of Kerguelen Island (Southern Ocean) |
| VerfasserIn |
C. Venchiarutti, M. Roy-Barman, R. Freydier, P. Beek, M. Souhaut, C. Jeandel |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1726-4170
|
| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 8, no. 11 ; Nr. 8, no. 11 (2011-11-08), S.3187-3201 |
| Datensatznummer |
250006195
|
| Publikation (Nr.) |
 copernicus.org/bg-8-3187-2011.pdf |
|
|
|
|
|
| Zusammenfassung |
Dissolved and particulate excess 230Th and 231Pa concentrations
(noted 230Thxs and 231Paxs respectively) and
231Paxs/230Thxs activity ratios were investigated on and
out of the Kerguelen plateau (Southern Ocean) in the framework of the
Kerguelen Ocean and Plateau compared Study project in order to better
understand the influence of particle flux and particle chemistry and
advection on the scavenging of 231Pa.
In the wake of Kerguelen, particulate 231Paxs is relatively
abundant compared to its content in the dissolved phase. This, together with
the low fractionation observed between 230Th and 231Pa
(FTh/Pa ranging from 0.06 ± 0.01 to 1.6 ± 0.2) reflects the
domination of the biogenic silica in the particle pool.
Along the eastern escarpment of the Kerguelen plateau, the strong
231Paxs horizontal gradient in the deep waters highlights the
intense removal of 231Pa at depth, as already observed for
230Thxs. This local boundary scavenging was attributed to
re-suspension of opal-rich particles by nepheloid layers, resulting in
fractionation factors FTh/Pa ≤ 1 along the Kerguelen
plateau slope. Therefore, both the composition (biogenic opal) and the flux
(intense along the margin) of particles control the scavenging of the two
radionuclides in the Kerguelen wake.
The modelling of 231Pa distribution with an advection-scavenging model
demonstrates that lateral advection of open ocean water on the Kerguelen
plateau could supply most of the 231Pa, which is then efficiently
scavenged on the highly productive plateau, as previously proposed for
230Thxs. It stresses that lateral advection can play a significant
role in the overall budget of particle reactive trace elements in a
coastal-open ocean system. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|