Naslov
Uranium isotope geochemistry in modern coastal sediments: insights from Toulon Bay, France

Autori
Huy Dang, Duc ; Evans, R. Douglas ; Wang, Wei ; Omanović, Dario ; El Houssainy, Amonda ; Lenoble, Véronique ; Mullot, Jean-Ulrich ; Mounier, Stéphane ; Garnier, Cédric

Izvornik
Chemical geology (0009-2541) 481 (2018); 133-145

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
Uranium ; Coastal sediments ; Diagenesis ; Uranium isotope composition ; Multiple regression

Sažetak
By assessing U geochemistry as well as U isotopic composition in marine sediments of Toulon Bay, NW Mediterranean Sea, authigenic U accumulation was found to be tightly linked to that of Mo and V with slight differences in accumulation rate depending on sediment redox conditions. In sediments collected on a transect along a river plume, the authigenic accumulation of these redox-sensitive elements appears to be linked to sediment grain size which probably drives the redox status of the sediments. A typical U loss in re-oxidized sediments was observed in sediments that had been previously disturbed. However, the dissolved U profiles do not show a simple and typical depletion trend but rather a depletion in the top 10 cm followed by release in deeper pore waters that could be linked to a potential reoxidation/mobilization of authigenic U(IV). The released U could be further scavenged as a U-P precipitate. The U isotopic data (δ238U), which are the first reported for the coastal hypoxic sediments of Toulon Bay, average −0.12 ± 0.12‰ in surface sediments. However, sediments situated in front of river mouths show higher values of δ238U (up to +0.75‰) ; these high values are reported for the first time in sediments below an oxic water column

Izvorni jezik
Engleski

Znanstvena područja
Geologija, Kemija

POVEZANOST RADA