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A numerical investigation for dating 210Pbex and 137Cs vertical profiles in a coastal area: The Eastern Ligurian Sea, Italy

TitoloA numerical investigation for dating 210Pbex and 137Cs vertical profiles in a coastal area: The Eastern Ligurian Sea, Italy
Tipo di pubblicazioneArticolo su Rivista peer-reviewed
Anno di Pubblicazione2020
AutoriBuffoni, G., Schirone Antonio, and Delfanti Roberta
RivistaJournal of Environmental Radioactivity
Volume212
ISSN0265931X
Parole chiaveadvection, Advection and diffusions, article, atmospheric deposition, atmospheric fallout, bioaccumulation, cesium 137, cesium isotope, Chernobyl accident, Coastal sediments, coastal zone, Coastal zones, concentration (parameter), Conservation, continental shelf, controlled study, dating method, Denmark, diffusion, dispersion, Dispersion process, Environmental knowledge, fallout, Independent variables, Italy, lead 210, lead isotope, Ligurian Sea, Marine protected area, Mediterranean Sea, Mixing, Numerical investigations, numerical method, particulate matter, Radioisotopes, radiometric dating, railway, sea water, seashore, sediment, Sedimentation
Abstract

210Pb and 137Cs vertical profiles in coastal sediments are studied using a sedimentation-mixing model. The cores were sampled in a complex coastal area characterized by the presence of different impact sources and environmental uses (riverine inputs, commercial and military harbour, marine protected area) in the Eastern Ligurian Sea, Italy. The analysis of accumulation and dispersion processes is performed using a numerical advection and diffusion model, in terms of the independent variables - time and mass depth. The flux of 210Pb is considered in steady state while the time dependent input flux of 137Cs is estimated from the concentration of this radionuclide in seawater, starting from observed data from 1960 to date. Differently from the atmospheric fallout distribution, this input function contains, at least partly, the contribution that still continues to reach the sediment in the last 25 years as a result of coastal and riverine input. The analysis highlights some features obscured in experimental data, and allows comparison of the effects of different scenarios. The specific effect of a pulsed input is discussed by analysing the effects of the Chernobyl event. The effects of mass flux in non–steady state are also considered: we observe that since the pulsed inputs in 137Cs are now too old, a strong superficial mixing and a time-variable flux produce similar profiles for both radionuclides. Hence, the general environmental knowledge of the area remains the main instrument to fully define the active processes in some cores. © 2019

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URLhttps://www.scopus.com/inward/record.uri?eid=2-s2.0-85075803523&doi=10.1016%2fj.jenvrad.2019.106122&partnerID=40&md5=5cc67af0b9da11d19d65e79b64d51d14
DOI10.1016/j.jenvrad.2019.106122
Citation KeyBuffoni2020