210Pb and 137Cs radiochemistry, granulometry, and X-radiography data for sediment cores collected in East Bay of the Mississippi River Delta, Louisiana.

Sediment cores were collected in the summers of 2023, 2024, and 2025 on the R/V Point Sur in East Bay of the Mississippi River Delta. Core types include gravity cores and piston cores. Core names in this dataset follow a standardized naming convention that identifies the research vessel, year collected, cruise number, sampling station, coring attempt and core type GC = gravity core, and PC = piston core). Locations for all cores were selected to target specific depositional environments following geomorphic analysis of existing bathymetric and subbottom acoustic data. Cores were analyzed for radiochemistry, granulometry, and x-radiography. The primary radionuclides of interest were 210Pb (t1/2 = 22.2 years) and 137Cs (t1/2 = 30.1 years), used to measure sediment accumulation over decadal timescales. Radioisotope content was determined using Mirion/Canberra germanium gamma-ray spectrometers, and radioactivity is reported in decays per minute per gram sediment (dpm/g), where 1 dpm equals 60 Becquerel (Bq). For granulometric analysis, subsamples of ~1 cm3 were deflocculated with 0.05 percent NaPO3 solution, centrifuged to remove the supernatant, and placed in a hot bath for > 10 h with H2O2 solution to digest organics. Samples were subsequently analyzed in a Beckman-Coulter LS13-320 laser diffraction particle size analyzer. Sedimentary fabric was studied through X-radiographic imaging of archived core sections. Cores were imaged digitally using Min Xray HF-80 X-ray generator illuminating a Samsung LTX-1717 X-ray detector panel with a parabolic aluminum compensator plate to normalize brightness across semicylindrical core sections. Images were then processed with IMAGE-J software, in which darker shades of gray correspond to higher wet bulk density (e.g., sand and coarse silt), and light gray to white correspond to voids and sediments of lower wet bulk density and higher porosity (e.g., mud). X-radiographs were studied to identify dominant physical sedimentary structures and fabrics, together with bioturbation intensity.