Particulate organic carbon export fluxes in the Canada Basin and Bering Sea as derived from Th-234/U-238 disequilibria
Seawater samples were collected in the water column of the Canada Basin and the Bering Sea from aboard the R/V Xue Long during August 1999. Activity concentrations of dissolved and particulate Th-234 were measured using beta counting techniques to quantify the scavenging and residence time of Th-234...
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ftxiamenuniv:oai:dspace.xmu.edu.cn:2288/60948 2023-05-15T14:21:24+02:00 Particulate organic carbon export fluxes in the Canada Basin and Bering Sea as derived from Th-234/U-238 disequilibria Chen, M. Huang, Y. P. Cai, P. G. Guo, L. D. 黄奕普 2003-03 http://dspace.xmu.edu.cn/handle/2288/60948 en_US eng Arctic, 2003,56(1):32-44 0004-0843 ISI:000182434600004 http://dspace.xmu.edu.cn/handle/2288/60948 CENTRAL ARCTIC-OCEAN MARGINAL ICE-ZONE HETEROTROPHIC BACTERIOPLANKTON EQUATORIAL PACIFIC TIME-SERIES WATERS NUTRIENT BIOMASS TRACER RADIONUCLIDES Article 2003 ftxiamenuniv 2020-07-21T11:32:28Z Seawater samples were collected in the water column of the Canada Basin and the Bering Sea from aboard the R/V Xue Long during August 1999. Activity concentrations of dissolved and particulate Th-234 were measured using beta counting techniques to quantify the scavenging and residence time of Th-234 and organic carbon export fluxes. Primary production (PP) and bacterial production were also determined in the study areas through in situ incubation experiments. Significant Th-234 scavenging was observed in the upper 100 m of the water column in both study areas, with up to 40% of Th-234 deficit found at Bering Sea stations and similar to15% of Th-234 deficit at the Canada Basin station. Measured PP decreased from similar to12.5 mumol C/m(3)/h in surface water to near zero at similar to100 m depth, with an integrated PP of 3.83 mmol C/m(2)/d in the Canada Basin. Bacterial production, on the other hand, was on the order of 2.0 mmol C/m(2)/d, which is up to 52% of the integrated PP. Particulate organic carbon (POC) export fluxes derived from Th-234/U-238 disequilibrium were similar to1 mmol C/m(2)/d in the Canada Basin and similar to10 mmol C/m(2)/d in the Bering Sea, with fluxes in the latter area being 5 to 10 times higher than those found in the Canada Basin. These export fluxes correspond to a ThE ratio (the ratio of Th-234-derived POC export to primary production) of 0.26 for the Canada Basin and 0.7 for the Bering Sea. The higher ThE ratios in the study areas suggest a decoupling of production and particulate export in the high-latitude ocean. Ratios of POC to particulate Th-234 (mumol C/dpm) decreased consistently with increasing depth, suggesting that organic carbon is preferentially remineralized relative to Th-234. Interestingly, the profile of particulate Th-234 in the Canada Basin showed a unique characteristic: particulate Th-234 activities increased with increasing depth, suggesting a continuous scavenging of Th-234 and a rapid settling rate of the particles. Article in Journal/Newspaper Arctic Arctic Arctic Ocean Bering Sea canada basin Central Arctic Xiamen University Institutional Repository Arctic Arctic Ocean Bering Sea Canada Pacific |
institution |
Open Polar |
collection |
Xiamen University Institutional Repository |
op_collection_id |
ftxiamenuniv |
language |
English |
topic |
CENTRAL ARCTIC-OCEAN MARGINAL ICE-ZONE HETEROTROPHIC BACTERIOPLANKTON EQUATORIAL PACIFIC TIME-SERIES WATERS NUTRIENT BIOMASS TRACER RADIONUCLIDES |
spellingShingle |
CENTRAL ARCTIC-OCEAN MARGINAL ICE-ZONE HETEROTROPHIC BACTERIOPLANKTON EQUATORIAL PACIFIC TIME-SERIES WATERS NUTRIENT BIOMASS TRACER RADIONUCLIDES Chen, M. Huang, Y. P. Cai, P. G. Guo, L. D. 黄奕普 Particulate organic carbon export fluxes in the Canada Basin and Bering Sea as derived from Th-234/U-238 disequilibria |
topic_facet |
CENTRAL ARCTIC-OCEAN MARGINAL ICE-ZONE HETEROTROPHIC BACTERIOPLANKTON EQUATORIAL PACIFIC TIME-SERIES WATERS NUTRIENT BIOMASS TRACER RADIONUCLIDES |
description |
Seawater samples were collected in the water column of the Canada Basin and the Bering Sea from aboard the R/V Xue Long during August 1999. Activity concentrations of dissolved and particulate Th-234 were measured using beta counting techniques to quantify the scavenging and residence time of Th-234 and organic carbon export fluxes. Primary production (PP) and bacterial production were also determined in the study areas through in situ incubation experiments. Significant Th-234 scavenging was observed in the upper 100 m of the water column in both study areas, with up to 40% of Th-234 deficit found at Bering Sea stations and similar to15% of Th-234 deficit at the Canada Basin station. Measured PP decreased from similar to12.5 mumol C/m(3)/h in surface water to near zero at similar to100 m depth, with an integrated PP of 3.83 mmol C/m(2)/d in the Canada Basin. Bacterial production, on the other hand, was on the order of 2.0 mmol C/m(2)/d, which is up to 52% of the integrated PP. Particulate organic carbon (POC) export fluxes derived from Th-234/U-238 disequilibrium were similar to1 mmol C/m(2)/d in the Canada Basin and similar to10 mmol C/m(2)/d in the Bering Sea, with fluxes in the latter area being 5 to 10 times higher than those found in the Canada Basin. These export fluxes correspond to a ThE ratio (the ratio of Th-234-derived POC export to primary production) of 0.26 for the Canada Basin and 0.7 for the Bering Sea. The higher ThE ratios in the study areas suggest a decoupling of production and particulate export in the high-latitude ocean. Ratios of POC to particulate Th-234 (mumol C/dpm) decreased consistently with increasing depth, suggesting that organic carbon is preferentially remineralized relative to Th-234. Interestingly, the profile of particulate Th-234 in the Canada Basin showed a unique characteristic: particulate Th-234 activities increased with increasing depth, suggesting a continuous scavenging of Th-234 and a rapid settling rate of the particles. |
format |
Article in Journal/Newspaper |
author |
Chen, M. Huang, Y. P. Cai, P. G. Guo, L. D. 黄奕普 |
author_facet |
Chen, M. Huang, Y. P. Cai, P. G. Guo, L. D. 黄奕普 |
author_sort |
Chen, M. |
title |
Particulate organic carbon export fluxes in the Canada Basin and Bering Sea as derived from Th-234/U-238 disequilibria |
title_short |
Particulate organic carbon export fluxes in the Canada Basin and Bering Sea as derived from Th-234/U-238 disequilibria |
title_full |
Particulate organic carbon export fluxes in the Canada Basin and Bering Sea as derived from Th-234/U-238 disequilibria |
title_fullStr |
Particulate organic carbon export fluxes in the Canada Basin and Bering Sea as derived from Th-234/U-238 disequilibria |
title_full_unstemmed |
Particulate organic carbon export fluxes in the Canada Basin and Bering Sea as derived from Th-234/U-238 disequilibria |
title_sort |
particulate organic carbon export fluxes in the canada basin and bering sea as derived from th-234/u-238 disequilibria |
publishDate |
2003 |
url |
http://dspace.xmu.edu.cn/handle/2288/60948 |
geographic |
Arctic Arctic Ocean Bering Sea Canada Pacific |
geographic_facet |
Arctic Arctic Ocean Bering Sea Canada Pacific |
genre |
Arctic Arctic Arctic Ocean Bering Sea canada basin Central Arctic |
genre_facet |
Arctic Arctic Arctic Ocean Bering Sea canada basin Central Arctic |
op_relation |
Arctic, 2003,56(1):32-44 0004-0843 ISI:000182434600004 http://dspace.xmu.edu.cn/handle/2288/60948 |
_version_ |
1766294072357552128 |