Evidence of minimal carbon sequestration in the productive Amundsen Sea polynya

The Amundsen Sea polynya (ASP) is reportedly the most productive among the coastal polynyas around Antarctica. However, observational constraints limit our understanding of the biological pump and carbon cycle in the ASP. We measured various carbon-related parameters such as primary production, bacterial production, sinking flux of particulate organic carbon (POC), and accumulation of organic carbon in the sediment as well as hydrographic parameters during field observations and by instrument moorings. Over 95% of the photosynthetically produced POC was converted to suspended POC and/ or dissolved carbon forms in the upper similar to 400 m layer. We postulate that most of the carbon transported to the water column by the biological pump in the ASP was flushed out of the shelf without being sequestered for long-term storage in sediments. Lack of bottom water formation due to intrusion of Circumpolar Deep Water in the lower layer reduces carbon sequestration efficiency.We thank M. Kim, H. Kim, H. Jeon, H. Joo, A. Choi, S. Kim, and M. Erickson for sample analyses; A. Post and P. Abrahamsen for deploying the USA sediment trap; C. Hwang and H. Kim for their discussions on the manuscript; and the officers and crew of the IBRV Araon for their field assistance. We thank two anonymous reviewers who provided thorough and constructive comments on the manuscript. We acknowledge the use of Rapid Response imagery from the Land, Atmosphere Near real-time Capability for EOS ( LANCE) system operated by the NASA/GSFC/Earth Science Data and Information System (ESDIS) with funding provided by NASA/HQ. This study was supported by KOPRI grants PP 16020 (S.L.), PE11050 (H.C.S.), and NRF-2015K2A3A1000201 (H.K.H.), and U.S. NSF-ANT award 0839012 (H.W.D.). The data used are listed in the references and in the supporting information