Gamma 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 7 sediment cores (Sites 4, 8, 14, 15, 20, 21, 27). Samples were analysed for a few sediment depths to resolve the overall activity profile, then additional samples were analysed to resolve activity peaks. Not all samples were analysed for each 40 cm core section. Sediments were measured for 210Pb, 137Cs, and 241Am using Mirion (Canberra) Canberra High Purity Germanium (HPGe) well-type gamma spectrometers (GAU-Radioanalytical, University of Southampton) under their accreditation to ISO/IEC17025. Data acquisition was performed using Genie-2000 (Mirion Canberra) and spectral analysis was performed using Fitzpeaks 32 deconvolution software. The HPGe detectors were efficiency calibrated using a certified, mixed gamma radionuclide standard (National Physical Laboratory, UK) which was homogenised into a near-identical sample matrix to that of the test sample. Samples were counted for 8 hours to achieve low limits of detection.