海水中^(131)I的快速检测技术

Rapid Detection Method of ^(131)I in Seawater

日本福岛核事故发生以后,对海洋环境中关键放射性核素的快速检测技术提出了更高的要求。人工放射性核素^(131)I在核反应裂变产物中活度相对较高且半衰期短,是用来快速评价核污染的关键性核素之一。本工作从亚铁氰化钾、硝酸铜及硝酸银为原料出发,制备出亚铁氰化铜和亚铁氰化银混合(CuFC/AgFC)吸附材料并分散于聚丙烯纤维富集柱上,来实现水环境中^(131)I现场快速富集。通过室内模拟实验发现:在流速为6.25L/min,^(131)I在海水中I^-初始浓度为24μmol/L时,单次吸附效率即可达到50%以上;而当海水中I^-初始浓度为4μmol/L时,一定体积的海水在连续循环8次后(CuFC/AgFC)聚丙烯纤维富集柱吸附效率达到100%。本方法制源时间约40min,测样时间约12~24h,故最快可在30h内完成海水中^(131)I的分析。本方法的检测限与分析周期均低于目前GB/T 13272-1991水中^(131)I的分析标准,极大地提高了^(131)I的分析时间。除此之外,该法可以同时分析海水中的^(137) Cs(^(134) Cs),有望作为淡水和近岸环境中常规监测和应急时对关键核素^(131)I和^(137) Cs(^(134) Cs)进行快速测定的备选方法之一。

After the Fukushima nuclear accident,the rapid detection of critical radionuclides in the marine environment has been required.131 I,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 131 I.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 131 I by one cycle time of seawater can reach 50%when the initial concentration of I(as I-form)is 24μmol/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 4μmol/L.It usually takes 40 minutes to prepare the targets after the enrichment experient,and then 12-24 hours for the 131 I analysis by HPGe-gamma spectrometry.Therefore,the method of 131 I in seawater in the present work can be completed in 30 h,which significantly improves the analysis for 131 I.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 137 Cs(134 Cs)in seawater simultaneously,which is expected to be one of the alternative methods to rapidly detect 131 I and 137 Cs(134 Cs)in freshwater/seawater nearshores for routine monitoring and also emergency cases.