The influence of sedimentation regime on natural radionuclide activity concentration in marine sediments of the East Siberian Arctic Shelf

• Published in: Journal of environmental radioactivity 2022-11, Vol.253-254, p.106988-106988, Article 106988
• Main Authors: Charkin, Alexander N., Yaroshchuk, Elena I., Dudarev, Oleg V., Leusov, Andrei E., Goriachev, Vladimir A., Sobolev, Igor S., Gulenko, Timofey A., Pipko, Irina I., Startsev, Anatoly M., Semiletov, Igor P.
• Format: Article
• Language: English
• Subjects: East siberian arctic shelf; Marine sediments; Natural radionuclides; Organic carbon; Paleo-river valleys; Sedimentation regime
• ISSN: 0265-931X; 1879-1700
• DOI: 10.1016/j.jenvrad.2022.106988

Transport and accumulation of radionuclides in the Arctic depends on many biogeochemical processes, which are changing at accelerated rates due to climate change and human economic activity. We present the results of a study on the features distribution of some natural radionuclides in the marine sediments on the East Siberian Arctic Shelf collected during several expeditions from 2008 to 2019. Average activity concentration of 232Th, 40K and 226Ra under the influence of different sedimentation regime increases from 40.7, 418 and 30.8 Bq/kg to 41.6, 423 and 34.9 Bq/kg respectively from coastal shelf marine sediments (50% clay). Sediment particle size has a greater impact on radionuclides in the coastal shelf. An increase in the activity concentrations of 232Th and 226Ra with the increasing clay particles were found. On the outer shelf with a change in the sedimentation regime, the influence of the size composition decreased, at the same time, there is a correlation between the organic carbon concentration and the radionuclide activity concentration. Absolute maximums of natural radionuclide activity concentration (232Th = 70.9, 226Ra = 70.4, 40K = 591 Bq/kg) were detected in the Chaun Bay. The highest activity concentration of 226Ra was found in paleo-river valleys marine sediments. A low 232Th/226Ra activity concentration ratio indicates the enrichment of paleo-river valleys marine sediments with 226Ra. In the deep-sea sediments of the shelf slope on the contrary paleo-river valleys, this ratio is greatly increased. •The activity concentration of natural radionuclides increases from coast to outer ESAS.•Sediment particle size has a greater impact on radionuclides in the coastal ESAS.•On the outer ESAS, the influence of biogenic OM on radionuclides increases.•The highest activity concentration of 226Ra was found in paleo-river valleys marine sediments.