Excess of (236)U in the northwest Mediterranean Sea.
In this work, we present first (236)U results in the northwestern Mediterranean. (236)U is studied in a seawater column sampled at DYFAMED (Dynamics of Atmospheric Fluxes in the Mediterranean Sea) station (Ligurian Sea, 43°25'N, 07°52'E). The obtained (236)U/(238)U atom ratios in the dissolved phase, ranging from about 2×10(-9) at 100m depth to about 1.5×10(-9) at 2350m depth, indicate that anthropogenic (236)U dominates the whole seawater column. The corresponding deep-water column inventory (12.6ng/m(2) or 32.1×10(12) atoms/m(2)) exceeds by a factor of 2.5 the expected one for global fallout at similar latitudes (5ng/m(2) or 13×10(12) atoms/m(2)), evidencing the influence of local or regional (236)U sources in the western Mediterranean basin. On the other hand, the input of (236)U associated to Saharan dust outbreaks is evaluated. An additional (236)U annual deposition of about 0.2pg/m(2) based on the study of atmospheric particles collected in Monaco during different Saharan dust intrusions is estimated. The obtained results in the corresponding suspended solids collected at DYFAMED station indicate that about 64% of that (236)U stays in solution in seawater. Overall, this source accounts for about 0.1% of the (236)U inventory excess observed at DYFAMED station. The influence of the so-called Chernobyl fallout and the radioactive effluents produced by the different nuclear installations allocated to the Mediterranean basin, might explain the inventory gap, however, further studies are necessary to come to a conclusion about its origin.
Centro Nacional de Aceleradores, Universidad de Sevilla, Consejo Superior de Investigaciones Científicas, Junta de Andalucía, Thomas Alva Edison 7, 41092 Seville, Spain. Electronic address: echamizo@us.es.
E
E
Chamizo
Centro Nacional de Aceleradores, Universidad de Sevilla, Consejo Superior de Investigaciones Científicas, Junta de Andalucía, Thomas Alva Edison 7, 41092 Seville, Spain. Electronic address: mlopezlora@us.es.
M
M
López-Lora
IAEA-Environment Laboratories, Monte Carlo 98000, Monaco; Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, TAS, Australia. Electronic address: matthieu.bressac@utas.edu.au.
M
M
Bressac
IAEA-Environment Laboratories, Monte Carlo 98000, Monaco. Electronic address: I.N.Levy@iaea.org.
I
I
Levy
IAEA-Environment Laboratories, Monte Carlo 98000, Monaco. Electronic address: M.Pham@iaea.org.
M K
MK
Pham
D005602:France; D008522:Mediterranean Sea; D011834:Radiation Monitoring; D012623:Seawater / Q000737:chemistry*; D014501:Uranium / Q000032:analysis*; D014875:Water Pollutants, Radioactive / Q000032:analysis*
C000615177:Uranium-236; D014875:Water Pollutants, Radioactive; D014501:Uranium
(236)U; AMS; Saharan dust outbreaks; Seawater; Western Mediterranean Sea