Depth profiles of selected radionuclides and grain size in marine sediments of the West Gironde Mud Patch (Bay of Biscay)
|Temporal extent||2016-10-25 -2016-11-01|
|Affiliation(s)||1 : CNRS, UMR5805 EPOC|
|Keyword(s)||West Gironde Mud Patch, Bay of Biscay, continental shelf, 210Pb, 226Ra, 228Th, 137Cs, K, grain size, dry bulk density, sediment|
The West Gironde Mud Patch (WGMP) is a 420-km2 mud belt in the Bay of Biscay, located 25 km off the mouth of the Gironde estuary. This clay-silt feature of 4 m in thickness extends between 30 and 75m water depth, surrounded by the sands and gravels that cover the North Aquitaine continental shelf. Interface cores were collected during JERICOBent-1 cruise (October 2016; Deflandre (2016) doi.org/10.17600/16010400) along two cross-shelf transects for a total of 9 sites. Each sediment core was carefully extruded every 0.5 cm from the top core to 4 cm and every 1 cm below until the core bottom. The sediment layers were used to determine dry bulk density, grain size and selected radioisotope activities (210Pb, 226Ra, 137Cs, 228Th, K).
|Acknowledgments||This work was supported by: (1) the JERICO-NEXT project (European Union's Horizon 2020 Research and Innovation program under grant agreement no. 654410), (2) the VOG project (LEFE-CYBE R and EC2CO-PNEC), We are thankful to the French Nouvelle Aquitaine Research Council (E3A Project) for the co-funding of the low‐background gamma detector.|
Dry bulk density (DBD) determination: water content was determined by weighing each sediment samples before and after drying at 60°C, and dry bulk density was subsequently calculated, assuming a mineral density of 2.65 g/cm.
Sediment grain size was measured using a Malvern Mastersizer 2000 laser diffraction particle size analyzer.
Radionuclide activities were measured using a high-efficiency, broad energy gamma detector equipped with a Cryo-Cycle II (Mirion). The gamma detector is calibrated using IAEA certified materials (RGU-1). Errors on activities are based on standard deviation counting statistics