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ZHANG Run,CHEN Min,MA Qiang,CAO Jianping,QIU Yusheng. 2015. Insights into the coupling of upper ocean-benthic carbon dynamics in the western Arctic Ocean from an isotopic (13C, 234Th) perspective. Acta Oceanologica Sinica, 34(6):26-33
Insights into the coupling of upper ocean-benthic carbon dynamics in the western Arctic Ocean from an isotopic (13C, 234Th) perspective
西北冰洋表-底层碳动力学耦合作用的同位素(13C,234Th)指示
Received:May 12, 2014  Revised:October 28, 2014
DOI:10.1007/s13131-015-0684-x
Key words:δ13C  POC  sediment  carbon export flux  western Arctic Ocean
中文关键词:  δ13C  颗粒有机碳  沉积物  碳输出通量  西北冰洋
基金项目:Chinese Polar Environment Comprehensive Investigation and Assessment Programs under contract Nos CHINARE 2014- 03-04-03 and CHINARE 2014-04-03-05; the National Natural Science Foundation of China under contract Nos 41125020 and 41206062; a special scientific research project for public welfare under contract No. 201105022-4; the research project supported by the State Oceanic Administration under contract No. GASI-03-01-02-02; the Natural Science Foundation of Fujian Province of China under contract No. 2014J05049.
Author NameAffiliationE-mail
ZHANG Run College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China  
CHEN Min College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China
State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen 361102, China 
mchen@xmu.edu.cn 
MA Qiang College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China  
CAO Jianping College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China  
QIU Yusheng College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China
State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen 361102, China 
 
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Abstract:
      The coupling of upper ocean-benthic carbon dynamics in the ice-free western Arctic Ocean (the Chukchi Sea and the Canada Basin) was evaluated during the late July-early September 2003 using natural stable (13C) and radioactive (238U-234Th) isotope tracers. POC export flux estimated from 234Th/238U disequilibria and dissolved CO2 concentration ([CO2(aq)]) pointed out that the strengthened biological pump in the Chukchi Shelf have significantly lowered [CO2(aq)] and altered the magnitude of isotopic (12C/13C) fractionation during carbon fixation in the surface ocean. Further, δ13C signatures of surface sediments (δ13Csed) are positively correlated to those of weighted δ13CPOC in upper ocean (δ13Csed =13.64+1.56×δ13CPOC, r2=0.73, p<0.01), suggesting that the POC isotopic signals from upper ocean have been recorded in the sediments, partly due to the rapid export of particles as evidenced by low residence times of the highly particle-reactive 234Th from the upper water column. It is suggested that there probably exists an upper ocean-benthic coupling of carbon dynamics, which likely assures the sedimentary δ13C record an indicator of paleo-CO2 in the western Arctic Ocean.
中文摘要:
      中文 本研究将天然稳定同位素(13C)与放射性核素(234Th/238U)相结合,研究了2003年7月末-9月初无冰覆盖的西北冰洋(楚科奇海和加拿大海盆)上层海洋—底层碳动力学的耦合过程。颗粒有机碳(POC)输出通量和溶解CO2浓度([CO2(aq)])的空间变化表明,楚科奇海陆架区加强的生物泵作用明显降低了表层溶解CO2含量([CO2(aq)]),进而改变了海洋生物固碳过程中的碳同位素分馏程度。表层沉积物碳稳定同位素组成(δ13Csed)与上层水柱颗粒有机物的碳同位素组成(δ13CPOC)之间呈显著的正相关关系(δ13Csed=13.64+1.56×δ13CPOC, r2=0.73,p<0.01),说明来自上层海洋的POC稳定同位素信号被较好地保留在沉积物中。另一方面,强颗粒活性核素234Th在上层海洋的停留时间较短,在一定程度上导致了来自上层海洋的颗粒有机碳同位素信号较好地传递至沉积物中。总而言之,西北冰洋存在上层海洋—底层碳动力学的耦合作用,这为运用沉积物颗粒有机物δ13C值反演海水CO2浓度的历史变化提供了可能。
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