Depth profiles of selected radionuclides in marine sediments of three macrotidal saltmarshes of the French Atlantic coast

Three saltmarshes, Aiguillon, Brouage, Fier d'Ars, located in the Pertuis-Charentais Sea along the south-west coast of France, were studied to evaluate their sediment and mass accumulation rates (SAR; MAR) based on 210Pb and 137Cs profiles in sediments. Coastal saltmarshes play indeed an essential role in providing services such as coastal protection and supporting biodiversity. Saltmarshes are also critical environments for the accumulation of sedimentary organic carbon (blue carbon). However, the number of studies on saltmarshes remains underrepresented compared to studies on mangroves and seagrass. This work is a contribution to the effort to document sediment and mass accumulation rates of saltmarshes.A total of 16 1m sediment cores were collected in the three saltmarshes (Aiguillon, Brouage, Fier d'Ars) in 2021 and 2022 using an Eijkelkamp stainless steel peat sampler. Each sediment core was sampled every 1 cm from the top to the bottom of the core. The sediment layers were used to determine dry bulk density and selected radioisotope activities (210Pb, 226Ra, 137Cs, 228Th, 137Cs). Combining excess 210Pb and 137Cs has allowed to establish a reliable chronology of sediment deposition on a multidecadal timescale.

Disciplines

Marine geology

Keywords

Saltmarsh, 210Pb, Sediment, Pertuis-Charentais Sea, 226Ra, Bay of Biscay, 228Th, Sedimentation accumulation rate, 137Cs, Mass accumulation rate, Dry buld density

Location

46.5N, 45.7S, -0.9E, -1.6W

Devices

Dry bulk density (DBD) was determined at LIENS. For this purpose, the water content was determined by weighing each sediment sample before and after drying at 60°C, and the dry bulk density was then calculated, assuming a mineral density of 2.65 g/cm.

The radionuclide determinations were carried out at EPOC. The activities of 210Pb, 226Ra, 228TH and 137CS were measured with a high efficiency broad energy gamma detector equipped with a Cryo-Cycle II (@Mirion). The gamma detector was calibrated with IAEA certified materials (RGU-1; RTh-1). Errors on activities were based on standard deviation counting statistics.

Data

FileSizeFormatProcessingAccessend of embargo
Profiles of dry bulk density and selected radionuclides in Aiguillon sediment cores
78 KoCSVQuality controlled data 2026-10-14
Profiles of dry bulk density and selected radionuclides in Brouage sediment cores
52 KoCSVQuality controlled data 2026-10-14
Profiles of dry bulk density and selected radionuclides in Fier d'Ars sediment cores
53 KoCSVQuality controlled data 2026-10-14
How to cite
Sabine Schmidt, Benjamin Amann (2024). Depth profiles of selected radionuclides in marine sediments of three macrotidal saltmarshes of the French Atlantic coast. SEANOE. https://doi.org/10.17882/102639

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