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

Charkin, Alexander; Yaroshchuk, E. I.; Dudarev, Oleg V.; Leusov, A. E.; Goriachev, Vladimir A.; Соболев, Игорь Станиславович; Gulenko, Timofey A.; Pipko, I. I.; Startsev, Anatoly M.; Semiletov, I. P.

doi:10.1016/j.jenvrad.2022.106988

Cited by 10 publications

(4 citation statements)

References 35 publications

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“…The Laptev and East Siberian Seas are considered together as one shelf sea in this model, because a combination of water from both shelves will contribute to the flux of shelf‐derived elements that enters the TPD. The concentration of 232 Th, the parent isotope of 228 Ra, is similar in sediments on both shelves (Charkin et al., 2022). The surface area of the box extends from the coastline to the shelf break, defined by Jakobsson (2002) as 490 and 560 m for the Laptev and East Siberian Seas, respectively (bold contour line on Figures 1–3 indicates 500 m).…”

Section: Discussionmentioning

confidence: 97%

“…Advection in this area is generally along‐slope (in the Arctic Circumpolar Boundary Current) rather than perpendicular to the shelf (Pnyushkov et al., 2021). The flux of 228 Ra should be consistent along the lengths of the Laptev and East Siberian slopes due to similar concentrations of its parent isotope, 232 Th (Charkin et al., 2022). Thus, the along‐slope 228 Ra gradient is much lower than the cross‐slope gradient, and advection along the slope in the Circumpolar Boundary Current should not affect the relationship between 228 Ra activity and distance from the slope.…”

Section: Discussionmentioning

confidence: 99%

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Radium Isotopes as Tracers of Shelf‐Basin Exchange Processes in the Eastern Arctic Ocean

Kipp,

Charette,

Robbins

et al. 2023

JGR Oceans

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Radium isotopes, which are sourced from sediments, are useful tools for studying potential climate‐driven changes in the transfer of shelf‐derived elements to the open Arctic Ocean. Here we present observations of radium‐228 and radium‐226 from the Siberian Arctic, focusing on the shelf‐basin boundary north of the Laptev and East Siberian Seas. Water isotopes and nutrients are used to deconvolve the contributions from different water masses in the study region, and modeled currents and water parcel back‐trajectories provide insights on water pathways and residence times. High radium levels and fractions of meteoric water, along with modeled water parcel back‐trajectories, indicate that shelf‐ and river‐influenced water left the East Siberian Shelf around 170°E in 2021; this is likely where the Transpolar Drift was entering the central Arctic. A transect extending from the East Siberian Slope into the basin is used to estimate a radium‐228 flux of 2.67 × 107 atoms m−2 d−1 (possible range of 1.23 × 107–1.04 × 108 atoms m−2 d−1) from slope sediments, which is comparable to slope fluxes in other regions of the world. A box model is used to determine that the flux of radium‐228 from the Laptev and East Siberian Shelves is 9.03 × 107 atoms m−2 d−1 (possible range of 3.87 × 107–1.56 × 108 atoms m−2 d−1), similar to previously estimated fluxes from the Chukchi Shelf. These three shelves contribute a disproportionately high amount of radium to the Arctic, highlighting their importance in regulating the chemistry of Arctic surface waters.

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Section: Discussionmentioning

confidence: 97%

Section: Discussionmentioning

confidence: 99%

Radium Isotopes as Tracers of Shelf‐Basin Exchange Processes in the Eastern Arctic Ocean

Kipp,

Charette,

Robbins

et al. 2023

JGR Oceans

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“…The western part of the ESS is strongly influenced by the simultaneous fresh water flow from the Indigirka River and the influx of the low-saline waters from the Laptev Sea. In addition, tidal currents also affect the salinity and temperature regime of the area [42,43]. In such conditions, only certain species are able to survive, so this aquatic area has low ostracod diversity.…”

Section: A Comparison Of the Ostracod Assemblages From The Western Pa...mentioning

confidence: 99%

“…The strong differences in the ostracod assemblages in Zones 3 and 4 are also due to the different types of sediment in these areas. The central part of the Chaun Bay is characterized by mud [36,43], while in the coastal part the sediments contain higher sand content and even stones [36]. In the eastern part of the EES adjacent to the Chaun Bay, ostracod fauna are more diverse than in the area of the Indigirka river mouth and less varied compared to the Chaun Bay (Appendix A, Table A4).…”

Section: A Comparison Of the Ostracod Assemblages From The Western Pa...mentioning

confidence: 99%

Ostracod Assemblages in the East Siberian Sea: A Comparative Study of River-Influenced and River-Isolated Shelf Ecosystems

Zenina,

Ovsepyan,

Ovsepyan

2024

Quaternary

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The East Siberian Sea (ESS) is one of the least studied seas in terms of ostracod fauna. Ostracods are sensitive organisms to environmental changes, and detailed information on their ecology is still required. To fill this knowledge gap, we studied 33 meiobenthic dredge samples collected from the western part of the ESS and the Chaun Bay together with 17 grab samples taken from the eastern part of the sea. Quantitative analyses of the ostracod assemblages demonstrate that the river-influenced western part of the ESS is inhabited by low diverse and impoverished fauna consisting of the taxa which are able to adapt to different environmental conditions. In the isolated Chaun Bay sheltered from significant riverine influence, the ostracod assemblages contain species that prefer more stable conditions. The predominance of living specimens over dead ones and individual valves points to strong carbonate dissolution that is more pronounced in the western ESS than in the Chaun Bay. The formation of such conditions might be related to the high content of dissolved carbon dioxide resulting from bacterial remineralization of in situ produced and land-derived organic matter in the bottom sediments and low pH near the seabed. Numerous ferromanganese crusts were found on the ostracod valve surfaces and inside the shells from the Chaun Bay.

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Radioactivity concentration and risk indices in intertidal sediments of the Red River Delta, Vietnam

Van Vuong,

Hai,

Van Chien

et al. 2024

Environ Earth Sci

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The radioactivity concentration in eleven intertidal sediment cores in the Red River Delta was determined 40 K, 232 Th, and 226 Ra as well as radiological hazard indices for environmental risk assessment.The radioactivity concentrations of 40 K, 232 Th, and 226 Ra were 656 Bq/kg, 49.8 Bq/kg, and 37.0 Bq/kg, respectively. The radium equivalent activity (Raeq) was 158.7 Bq/kg; the absorbed dose rate (ADR) was 74.5 nGy/h; the annual effective dose equivalent (AEDE) was 0.09 mSv/y; the representative gamma index (Iγr) was 1.18; the activity utilization index (AUI) was 1.0; the external hazard index (Hex) was 0.40; the annual gonadal dose equivalent (AGDE) was 496.4 µSv/y. Two sediment groups were split. Group 1 with lower the radioactivity concentrations than Group 2, 40 K and 232 Th were above the global average while 226 Ra was below, Iγr and AGDE were above UNSCEAR's recommended levels. Group 2 radioactivity concentrations of 40 K, 226 Ra, and 232 Th were higher than global average; radiological hazard indices were higher than Group 1; the AUI, Iγr, and AGDE indices were above UNSCEAR's recommended level.The radioactivity concentrations of 40 K, 232 Th, and 226 Ra were above global average. The AUI, Iγr and AGDE indices were above UNSCEAR's recommended levels. It is recommended that coastal sediments should not be used for construction purposes as this can affect organisms in intertidal areas.

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

Cited by 10 publications

References 35 publications

Radium Isotopes as Tracers of Shelf‐Basin Exchange Processes in the Eastern Arctic Ocean

Radium Isotopes as Tracers of Shelf‐Basin Exchange Processes in the Eastern Arctic Ocean

Ostracod Assemblages in the East Siberian Sea: A Comparative Study of River-Influenced and River-Isolated Shelf Ecosystems

Radioactivity concentration and risk indices in intertidal sediments of the Red River Delta, Vietnam

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