Distribution of dissolved inorganic radiocarbon in the Amundsen Sea, Antarctica

• Main Author: 김범수
• Other Authors: 황점식, Kim, Bumsoo, 자연과학대학 지구환경과학부
• Format: Thesis
• Language: English
• Published: 서울대학교 대학원 2016
• Subjects: dissolved inorganic carbon; radiocarbon; the Amundsen Sea; polynya; air-sea gas exchange; 550; Amundsen Sea; Austral; Dotson Ice Shelf; Southern Ocean; Antarc*; Antarctica; Ice Shelf; Sea ice
• Online Access: http://hdl.handle.net/10371/131426

학위논문 (석사)-- 서울대학교 대학원 : 지구환경과학부, 2016. 8. 황점식. The Amundsen Sea is experiencing rapid change in sea-ice cover and ice shelf melting. It has the most productive polynya, the Amundsen Sea polynya. However, the inorganic carbon cycling associated with this polynya is yet poorly determined. In this study, I have examined the distribution of dissolved inorganic radiocarbon (DIC) in three different oceanographic regions in the Amundsen Sea: in the sea-ice zone (SIZ), inside the Amundsen Sea polynya, and near the Dotson Ice Shelf. In the upper 300 m layers, the average radiocarbon value in ∆14C in the polynya (−135 ‰) was considerably higher than that in the SIZ (−150 ‰). ∆14C value of Winter Water (WW) end-member was −147 ‰. The ∆14C values near the sea floor at each site were close to the value of the Circumpolar Deep Water (CDW), reflecting the intrusion of this water mass to the shelf near the sea floor. Contribution of carbon from processes such as glacial meltwater (GMW) input, benthic efflux, and remineralization of sinking organic particles in the water column was negligible to change the radiocarbon values of DIC in the water column. Air-sea gas exchange appears to be the primary process to increase radiocarbon content in the upper layer. Based on the observed discrepancy in ∆14C value between the SIZ and the polynya, absorption of atmospheric CO2 during the polynya opening in the austral summer was estimated. This study provides the preliminary data to understand the inorganic carbon cycling in this climate-sensitive region. 1. INTRODUCTION 1 1.1 Dissolved Inorganic Radiocarbon 1 1.2 Radiocarbon Values in the Southern Ocean 3 1.3 The Amundsen Sea 4 1.4 Objectives 6 2. METHODS 9 2.1 Sample Collection and Analysis 9 3. RESULTS 14 3.1 Water Mass Structure in the Amundsen Sea 14 3.2 Carbon Isotopes Ratios (δ13C and Δ14C) of DIC 18 4. DISCUSSION 24 4.1 Distribution of Dissolved Inorganic Radiocarbon in the Amundsen Sea 24 4.2 Potential Sources of Carbon to DIC in the Amundsen Sea 28 4.2.1 Primary Productivity in the Surface Layer 28 4.2.2 Glacial Meltwater 30 4.2.3 Benthic Efflux 33 4.2.4 Remineralization of Sinking Particles 34 4.3 Air-Sea Gas Exchange of CO2 36 5. SUMMARY AND CONCLUSION 44 6. REFERENCES 46 ABSTRACT (IN KOREAN) 56 Master