Abstract
To evaluate the particle dynamics and estimate the POC (particulate organic carbon) export flux from the euphotic zone in the western Arctic Ocean, 234Th-238U disequilibrium was applied during the second Chinese National Arctic Research Expedition (July 15–September 26, 2003). The POC export fluxes are estimated from the measured profiles of the 234Th/238U activity ratios and the POC/PTh ratios. The average residence times of the particulate and dissolved 234Th in the euphotic zone are 33 d and 121 d, and their average export fluxes are 480 dpm/m2d and 760 dpm/m2d, respectively. The scavenging and removal processes of particle reactive elements are active in the upper layer of the Chukchi Sea. The average residence time of 234Th increases from shelf to basin, while the export fluxes of 234Th decrease. The estimated POC export fluxes from the euphotic zone vary from 2.1 to 20.3 mmol/m2d, indicating that the western Arctic Ocean is an important carbon sink in summer due to efficient biological pump.
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References
Aono T, Yamada M, Kudo I et al. 2005. Export fluxes of particulate organic carbon estimated from 234Th/238U disequilibrium during the Subarctic Pacific Iron Experiment For Ecosystem Dynamics Study. Prog. Oceanagr., 64: 263–282.
Arrigo K R, Dijken G V, Pabi S. 2008. Impact of a shrinking Arctic ice cover on marine primary production. Geophys. Res. Lett., 35: L19603.
Baskaran M, Swarzenski P M, Porcelli D. 2003. Role of colloidal material in the removal of 234Th in the Canada basin of the Arctic Ocean. Deep-Sea Res. Part I, 50: 1 353–1 373.
Bates N R, Moran S B, Hansell D A et al. 2006. An increasing CO2 sink in the Arctic Ocean due to sea-ice loss, Geophys. Res. Lett., 33: L23609.
Benitez-Nelson, Buesseler K O, Crossin G. 2000. Upper ocean carbon export, horizontal transport, and vertical eddy diffusivity in the southwestern Gulf of Maine. Cont. Shelf Res. 20(2000): 707–736.
Buesseler K O. 1998. The decoupling of production and particulate export in the surface ocean. Global Biogeochem. Cycles, 12: 297–310.
Buesseler K O, Benitez-Nelson C R, Moran S B et al. 2006. An assessment of particulate organic carbon to thorium-234 ratios in the ocean and their impact on the application of 234Th as a POC flux proxy. Mar. Chem., 100: 213–233.
Cai P, Huang Y, Chen M, Guo L et al. 2002. New production based on 228Ra-derived nutrient budgets and thorium-estimated POC export at an intercalibration station in the South China Sea. Deep-Sea Res. Part I, 49(1): 53–66.
Cai P, Rutgers van der Loeff M, Stimac I et al. Low export flux of particulate organic carbon in the central Arctic Ocean as revealed by 234Th: 238U disequilibrium. J. Geophy. Res. Oceans. (accepted)
Chen M, Huang Y, Cai P, et al. 2003. Particulate organic carbon export fluxes in the Canada Basin and Bering Sea as derived from 234Th/238U disequilibria. Arctic, 55: 32–44.
Coale K H, Bruland K W. 1985. 234Th: 238U disequilibria within the California Current. Limnol. Oceanogr., 30: 22–33.
Cochran J K, Barnes C, Achman D et al. 1995. Thorium-234/Uranium-238 disequilibrium as an indicator of scavenging rates and particulate organic carbon fluxes in the Northeast Water Polynya, Greenland. J. Geophy. Res. Oceans, 100: 4 399–4 410.
Gosselin M, Levasseur M, Wheeler P A et al. 1997. New measurements of phytoplankton and ice algal production in the Arctic Ocean. Deep-sea Res. Part II, 44: 1 623–1 644.
Gustafsson O, Buesseler K O, Geyer W R et al. 1998. An assessment of the relative importance of horizontal and vertical transport of particle-reactive chemicals in the coastal ocean. Cont. Shelf Res., 18(1998): 805–829.
Ku T L, Knauss K G, Mathieu G G. 1977. Uranium in open ocean: concentration and isotopic composition. Deep-Sea Res., 24(11): 1 005–1 017.
Liu Z L. 2003. Chinese National Arctic and Antarctic Data Center.
Liu Z L, Chen J F, Zhang T et al. 2007. The Size-fractionated chlorophyll α concentration and primary productivity in the Chukchi Sea and its northern Chukchi Plateau, Acta Oceanol. Sin., 27(12):4 953–4 962.
Ma Q, Chen M, Qiu Y et al. 2005. Regional estimates of POC export flux derived from thorium-234 in the western Arctic Ocean. Acta Oceanol. Sin., 24(6): 97–108.
Moran S B, Ellis K M, Smith J N. 1997. 234Th/238U disequilibrium in the central Arctic Ocean: implications for particulate organic carbon export, Deep-Sea Res. Part II, 44: 1 593–1 606.
Moran S B, Kelly R P, Hagstrom K et al. 2005. Seasonal changes in POC export flux in the Chukchi Sea and implications for water column-benthic coupling in Arctic shelves. Deep-Sea Res. Part II, 52: 3 427–3 451.
Trimble S M, Baskaran M. 2005. The role of suspended particulate matter in 234Th scavenging and 234Th-derived export fluxes of POC in the Canada Basin of the Arctic Ocean. Mar. Chem., 96: 1–19.
Yang Y L, Han X, Kusakabe M. 2004. POC fluxes from euphotic zone estimated from 234Th deficiency in winter in the northwestern North Pacific Ocean. Acta Oceanol. Sin., 23(1): 135–147.
Zeng X Z, Qiu M H, Yin M D et al. 2007. An in-situ analysis and measurement of thorium-234, uranium isotopes in sea water. Acta Oceanol. Sin., 26(3): 73–83.
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Supported by the National Natural Science Foundation of China (No. 40531007), the China Action Plan of the International Polar Year (Nos. 2009DFA22920 and 2008Po5040014-03), the International Science and Technology Cooperation (Nos. 2008DFA20420 and 2009DFA22920) and the Polar Atmospheric Environment Remote Sensing Monitoring Technique of the National High Technology Research and Development Program of China (863 Program) (No. N2008DFA20420)
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Yu, W., Chen, L., Cheng, J. et al. 234Th-derived particulate organic carbon export flux in the western Arctic Ocean. Chin. J. Ocean. Limnol. 28, 1146–1151 (2010). https://doi.org/10.1007/s00343-010-9933-1
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DOI: https://doi.org/10.1007/s00343-010-9933-1