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.

本研究针对3根沉积物岩芯（站位4、8、20）的表层40 cm沉积物，以1厘米分辨率取样得到的冷冻干燥沉积物开展放射性核素（radionuclide）分析。所有样品均经分析以解析通过γ射线能谱法（gamma spectrometry）识别出的活度峰。并非每一段40 cm岩芯段的所有样品均完成了分析。为制备用于α射线能谱法（alpha spectrometry）检测的样品，取等分试样并掺加209Po作为化学产率监测剂，随后采用王水（aqua regia）进行消解。将洁净银盘置于所得消解液中，实现210Po的自沉积。采用奥泰克Octete（Ortec Octete）α能谱仪对放射性核素210Po进行测量。数据采集工作由Genie-2000（Mirion Canberra公司）完成，谱图分析则借助Fitzpeaks 32解卷积软件开展。所有样品的计数时长均设置为8小时，以达到较低的检测限。