Alpha emitting radionuclides in sediment cores from the Western Irish Sea Mud Belt, June 2022

Radionuclide analysis was carried out on freeze-dried sediments sampled at 1 cm resolution from the top 40 cm of 3 sediment cores (Sites 4, 8, 20). Samples were analysed to resolve activity peaks identified by gamma spectrometry. Not all samples were analysed for each 40 cm core section. To prepare samples for alpha spectrometry, an aliquot of sample was spiked with 209Po as a chemical yield monitor and then digested using aqua regia. A clean silver disc was then placed in the resultant digest for 210Po autodeposition. Alpha spectrometry (Ortec Octete) was conducted to measure the radionuclide 210Po. Data acquisition was performed using Genie-2000 (Mirion Canberra) and spectral analysis was performed using Fitzpeaks 32 deconvolution software. Samples were counted for 8 hours to achieve low limits of detection.

本次研究对3个沉积物岩芯（站位4、8、20）顶部40cm范围内以1cm分辨率采集的冻干沉积物样品开展放射性核素分析。分析工作旨在解析通过γ能谱法（gamma spectrometry）识别出的活度峰，且并非所有40cm岩芯段的样品均完成了分析流程。为制备适用于α能谱法（alpha spectrometry）分析的样品，称取等分试样并掺入209Po作为化学产率监测剂，随后采用王水（aqua regia）进行消解；之后将洁净银盘置于所得消解液中，实现210Po的自发沉积。本次分析采用α能谱仪（Ortec Octete）对放射性核素210Po进行测量，数据采集环节使用Genie-2000（Mirion Canberra）完成，谱分析则通过Fitzpeaks 32解卷积软件实现，所有样品的计数时长设置为8小时，以达到较低的检测限。