TY - JOUR
T1 - Quantifying export production in the Southern Ocean
T2 - Implications for the Ba
xs proxy
AU - Hernandez-Sanchez, Maria T.
AU - Mills, Rachel A.
AU - Planquette, Hélène
AU - Pancost, Richard D.
AU - Hepburn, Laura
AU - Salter, Ian
AU - Fitzgeorge-Balfour, Tania
PY - 2011/12/1
Y1 - 2011/12/1
N2 - The water column and sedimentary Ba
xs distribution around the Crozet Plateau is used to decipher the controls and timing of barite formation and to evaluate how export production signals are recorded in sediments underlying a region of natural Fe fertilization within the Fe limited Southern Ocean. Export production estimated from preserved, vertical sedimentary Ba
xs accumulation rates are compared with published export fluxes assessed from an integrated study of the biological carbon pump to determine the validity of Ba
xs as a quantitative proxy under different Fe supply conditions typical of the Southern Ocean. Detailed assessment of the geochemical partitioning of Ba in sediments and the lithogenic end-member allows appropriate correction of the bulk Ba content and determination of the Ba
xs content of sediments and suspended particles. The upper water column distribution of Ba
xs is extremely heterogeneous spatially and temporally. Organic carbon/Ba
xs ratios in deep traps from the Fe fertilized region are similar to other oceanic settings allowing quantification of the inferred carbon export based on established algorithms. There appears to be some decoupling of POC and Ba export in the Fe limited region south of the Plateau. The export production across the Crozet Plateau inferred from the Ba
xs sedimentary proxy indicates that the Fe fertilized area to the north of the Plateau experiences enhanced export relative to equivalent Southern Ocean settings throughout the Holocene and that this influence may also have impacted the site to the south for significant periods. This interpretation is corroborated by alternative productivity proxies (opal accumulation,
231Pa
xs/
230Th
xs). Ba
xs can be used to quantify export production in complex settings such as naturally Fe-fertilized (volcanoclastic) areas, providing appropriate lithogenic correction is undertaken, and sediment focusing is corrected for along with evaluation of barite preservation.
AB - The water column and sedimentary Ba
xs distribution around the Crozet Plateau is used to decipher the controls and timing of barite formation and to evaluate how export production signals are recorded in sediments underlying a region of natural Fe fertilization within the Fe limited Southern Ocean. Export production estimated from preserved, vertical sedimentary Ba
xs accumulation rates are compared with published export fluxes assessed from an integrated study of the biological carbon pump to determine the validity of Ba
xs as a quantitative proxy under different Fe supply conditions typical of the Southern Ocean. Detailed assessment of the geochemical partitioning of Ba in sediments and the lithogenic end-member allows appropriate correction of the bulk Ba content and determination of the Ba
xs content of sediments and suspended particles. The upper water column distribution of Ba
xs is extremely heterogeneous spatially and temporally. Organic carbon/Ba
xs ratios in deep traps from the Fe fertilized region are similar to other oceanic settings allowing quantification of the inferred carbon export based on established algorithms. There appears to be some decoupling of POC and Ba export in the Fe limited region south of the Plateau. The export production across the Crozet Plateau inferred from the Ba
xs sedimentary proxy indicates that the Fe fertilized area to the north of the Plateau experiences enhanced export relative to equivalent Southern Ocean settings throughout the Holocene and that this influence may also have impacted the site to the south for significant periods. This interpretation is corroborated by alternative productivity proxies (opal accumulation,
231Pa
xs/
230Th
xs). Ba
xs can be used to quantify export production in complex settings such as naturally Fe-fertilized (volcanoclastic) areas, providing appropriate lithogenic correction is undertaken, and sediment focusing is corrected for along with evaluation of barite preservation.
UR - http://www.scopus.com/inward/record.url?scp=84855272504&partnerID=8YFLogxK
U2 - 10.1029/2010PA002111
DO - 10.1029/2010PA002111
M3 - Article (Academic Journal)
SN - 0883-8305
VL - 26
JO - Paleoceanography
JF - Paleoceanography
IS - 4
M1 - PA4222
ER -