RESUMO
The article provides a data on 160 samples of bottom sediments obtained from 48 stations during 60th cruise of R/V Akademik Oparin in the East Siberian Sea in Autumn 2020 (26 September - 11 November). It contains mean diameter of the particles, sorting coefficient, standard deviation, skewness, and kurtosis, values of percentiles (p5, p10, p16, p25, p50, p75, p84, p90, p95), lithology and mass percentage of >2 mm, 1-2 mm, 0.5-1 mm, 250-500 µm, 125-250 µm, 63-125 µm, 31-63 µm, 10-31 µm, 2-10 µm, and <2 µm fractions. The bottom sediments have been sampled in Chaun Bay of the East Siberian Sea from 9 to 21 October 2020 with Ekman (0.25 m2) and Van Veen (0.05 m2) samplers. The grain size data was obtained from laser diffraction method using a SHIMADZU SALD 2300 particle analyser. The data provides an overview on lithology and grain size properties of bottom sediments that will be useful to understand risks for climate changes in the Arctic. The data will help the researchers who work on the Arctic to assess a relationship between grain size properties of the bottom sediments and it sorption potential. A principal component analysis (PCA) can be performed to identify key parameters of the bottom sediments in assessment of sedimentation rates and it changes in the Arctic. Additionally, the data can be used in mapping a spatial distribution of above mentioned parameters for better understanding sedimentation rate changes in the East Siberian Sea and adjacent seas as well.
RESUMO
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) to outer 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.
