The magnitude and potential of the sedimentary carbon sink in the Eastern China Marginal Seas

Delta Marginal sea sediments offer one of the most stable and critical carbon repositories of sequestered organic carbon (OC). Quantification of the magnitude and the potential of OC sequestration in marginal sea sediments could provide data supporting the formulation of coastal carbon management strategies in the future. Nonetheless, controversies and difficulties still exist given the lack of integrity on statistical data, the incomplete understanding of the complex OC sources and the dynamic processes in the marginal seas. This work presents a systematic and holistic analysis of the OC stock and carbon stock accumulation rate (CSAR) in surface sediments (0-5 cm) of the Eastern China Marginal Seas (ECMS). The estimated total OC stock in the top 5 cm sediments in the ECMS (9.57 x 10(5) km(2)) was 201.48 +/- 15.98 Tg and the sequestration rate was 24.24 +/- 9.93 Tg per year. Because only the preservation of fresh terrestrial OC and the marine OC is regarded as a valid CO2 sink on modern timescale, we further elucidated the magnitude and the potential of the valid OC stocks and CSAR with different sources and ages based on the delta C-13 and Delta C-14. This study quantifies high resolution OC stock and CSAR and presents the magnitude and potential of the valid sedimentary carbon sink in the ECMS.