Rapid Detection Method of ¹³¹I in Seawater

After the Fukushima nuclear accident, the rapid detection of critical radionuclides in the marine environment has been required. ¹³¹I, an artificial radionuclide released from nuclear reaction with high activity but very short half-life, is one of the critical nuclides for rapid assessment of nuclear contamination. In the present study, the compound of CuFC/AgFC were embedded on the polypropylene fiber column to study the enrichment of ¹³¹I. The CuFC/AgFC enrichment column can adsorb iodine isotopes efficiently. These results show that within the flow rate of 6.25 L/min, the sorption efficiency of ¹³¹I by one cycle time of seawater can reach 50% when the initial concentration of I (as I^- form) is 24 μmol/L. However, the sorption efficiency by eight cycles times of seawater can reach 100% even when the initial concentration of I (as I^- form) is 4 μmol/L. It usually takes 40 minutes to prepare the targets after the enrichment experient, and then 12-24 hours for the ¹³¹I analysis by HPGe-gamma spectrometry. Therefore, the method of ¹³¹I in seawater in the present work can be completed in 30 h, which significantly improves the analysis for ¹³¹I. Both the detection limit and analysis time of this method in the present work are much lower than the current GB/T 13272-1991 standard. Moreover, this method can detect ¹³⁷Cs (¹³⁴Cs) in seawater simultaneously, which is expected to be one of the alternative methods to rapidly detect ¹³¹I and ¹³⁷Cs (¹³⁴Cs) in freshwater/seawater nearshores for routine monitoring and also emergency cases.