Speakers
Description
Quantification of marine radionuclides remains analytically demanding due to their ultratrace concentrations and the need for large sample volumes and extensive pretreatment procedures. Conventional protocols typically involve multi-day chemical separation, prolonged counting times, and sample transport to land-based laboratories, resulting in total turnaround times of several weeks to months. Such constraints significantly limit the capability for rapid response in the event of accidental releases from nuclear facilities, particularly under dynamic oceanographic conditions characterized by rapid advection, dispersion, and dilution.
Here, we report the development and field implementation of an onboard rapid analytical system for the determination of radiocesium (134Cs and 137Cs) in seawater. The method integrates accelerated pre-concentration chemistry with optimized gamma spectrometric measurement, enabling full onboard processing from large-volume seawater to quantification within hours. The pre-treatment and cesium concentration procedure, which previously required several days, has been reduced to approximately four hours without compromising analytical performance.
Using this system, we successfully quantified background 137Cs levels of approximately 1 mBq/kg directly onboard research vessels. The method allows analysis of two samples within 12 hours, achieving a minimum detectable activity (MDA) of <0.2 mBq/kg. Comparative analyses with conventional land-based laboratory methods showed agreement within 10% for more than 92% of samples.
To further validate analytical robustness, a full-process intercomparison was conducted using a certified reference seawater, including large-volume standard seawater pretreatment, chemical analysis, and instrumental measurement. Both 134Cs and 137Cs results exhibited biases within 10% of certified reference values, confirming the accuracy and reliability of the developed methodology.
Since 2023, this onboard rapid-detection system has been operationally deployed in South Korea’s official open-ocean radioactivity monitoring program, led by KIOST. The system has been deployed during repeated North Pacific expeditions aboard R/V ISABU, demonstrating its capability for real-time assessment of basin-scale radiocesium distribution and emergency-response readiness.