Determination of 14C concentration in coastal seawater of the Korean Peninsula using accelerator mass spectrometry

Abstract

Radiocarbon (14C) in seawater is a key tracer for investigating carbon cycling and air–sea exchange. This study quantified 14C concentrations in coastal seawater from 18 sites around the Korean Peninsula using accelerator mass spectrometry (AMS). A CO₂ extraction system optimized for 100 mL seawater samples was developed, achieving 85.5 ± 0.9 % recovery efficiency validated by certified reference materials. AMS results showed fraction modern carbon (fMC) values between 0.98 and 1.03, reflecting equilibrium with atmospheric 14CO₂. The East Sea exhibited relatively high fMC and Δ14C, likely due to open-ocean circulation. The West and South Seas showed lower fMC and negative Δ14C values, influenced by restricted mixing and terrestrial inputs. Average 14C concentrations were 4.99 × 10−3 Bq/L (East Sea), 5.22 × 10−3 Bq/L (West Sea), and 4.84 × 10−3 Bq/L (South Sea). These findings provide a regional baseline for coastal 14C and highlight the need for depth-resolved studies to better understand carbon dynamics.