Impact of Saharan dust events on radionuclide levels in Monaco air and in the water column of the northwest Mediterranean Sea. (January 2017)

• Record Type: Journal Article
• Authors: Pham, Mai Khanh; Chamizo, Elena; Mas Balbuena, José Luis; Miquel, Juan-Carlos; Martín, Jacobo; Osvath, Iolanda; Povinec, Pavel P.
• Is Part Of: Journal of environmental radioactivity. Volume 166:Part 1(2017:Jan.)
• Page Start: 2
• Page End: 9
• Publication Date: 2017-01
• Subjects: Air monitoring -- Radionuclides -- Saharan dust -- Northwest Mediterranean -- DYFAMED -- Sediment trap; Radioactivity -- Periodicals; Radiation, Background -- Periodicals; Radioecology -- Periodicals; Radioactive pollution -- Periodicals; Environmental Pollutants -- Periodicals; Radioactive Pollutants -- Periodicals; Radioactivity -- Periodicals; Radioécologie -- Périodiques; Pollution radioactive -- Périodiques; Fond de rayonnement -- Périodiques; 539.752
• DOI: 10.1016/j.jenvrad.2016.04.014
• Languages: English
• ISSNs: 0265-931X

Abstract

Abstract: Characterization of atmospheric aerosols collected in Monaco (2004–2008) and in sediment traps at 200 m and 1000 m water depths at the DYFAMED (Dynamics of Atmospheric Fluxes in the Mediterranean Sea) station (2004) was carried out to improve our understanding of the impact of Saharan dust on ground-level air and on the water column. Activity concentrations of natural ( 210 Pb, 210 Po, uranium and radium isotopes) and anthropogenic ( 137 Cs, 239 Pu, 240 Pu, and 239+240 Pu) radionuclides and their isotopic ratios confirmed a Saharan impact on the investigated samples. In association with a large particulate matter deposition event in Monaco on 20 February 2004, the 137 Cs (∼40 Bq kg −1 ) and 239+240 Pu (∼1 Bq kg −1 ) activities were almost a factor of two higher than other Saharan deposition dust events. This single-day particle flux represented 72% of the annual atmospheric deposition in Monaco. The annual deposition of Saharan dust on the sea was 232–407 mBq m −2 for 137 Cs and 6.8–9.8 mBq m −2 for 239+240 Pu and contributed significantly (28–37% for 137 Cs and 34–45% for 239+240 Pu) to the total annual atmospheric input to the northwest Mediterranean Sea. The 137 Cs/ 239+240 Pu activity ratios in dust samples collected during different Saharan dust events confirmed their global fallout origin or mixing with local re-suspended soil particles. In the sediment trap samples the 137 Cs activity varied by a factor of two, while the 239+240 Pu activity was constant, confirming the different behaviors of Cs (dissolved) and Pu (particle reactive) in the water column. The 137 Cs and 239+240 Pu activities of sinking particles during the period of the highest mass flux collected in 20 February 2004 at the 200 m and 1000 m water depths represented about 10% and 15%, respectively, of annual deposition from Saharan dust events. Highlights: Characterization of atmospheric aerosol particles collected at Monaco. Study of Saharan dust transport in NW Mediterranean. Dynamics of Atmospheric Fluxes in the Mediterranean Sea. Contribution of radionuclides to the total annual atmospheric input to the NW Mediterranean.