Vertical distribution of radiocaesium, plutonium and americium in the Catalan Sea (northwestern Mediterranean)

• Published in: Journal of environmental radioactivity 1995, Vol.26 (3), p.205-216
• Main Authors: Molero, J., Sanchez-Cabeza, J.A., Merino, J., Pujol, LL, Mitchell, P.I., Vidal-Quadras, A.
• Format: Article
• Language: English
• Subjects: Applied sciences; Exact sciences and technology; Natural water pollution; Pollution; Seawaters, estuaries; Water treatment and pollution
• ISSN: 0265-931X; 1879-1700
• DOI: 10.1016/0265-931X(94)00033-S

Caesium-137, 239,240Pu and 241Am concentration profiles (0–1000m) have been determined in unfiltered large volume water samples collected from the Catalan Sea (northwestern Mediterranean). Results showed that radiocaesium concentration decreases quickly through the water column while the transuranic concentration increases with depth, showing a faster migration to the bottom layers. Comparing our results with those reported by other authors (1975–1980), radiocaesium input from Chernobyl releases has been identified through the profile. In addition, transuranic concentrations have decreased considerably in the different layers of the profile. Integrated activities through the water column were 2.6 ± 0.2kBq m −2 for 137Cs, 23±3Bq m −2 for 239,240Pu and 1.5 ± 0.5Bq m −2 for 241 Am. According to the estimated inventory and the integrated fall-out in the Mediterranean area, about 56% of 137Cs, 27% of 239,240Pu and 4% of 241 Am which was deposited over the Mediterranean Sea by generalized fallout remains at present in the first 1000m of the water column. Vertical distribution of 239,240Pu 137Cs and 241Am 137Cs activity ratios showed a clear separation between transuranics and radiocaesium through the water profile. 241Am 239, 240Pu activity ratio revealed faster sinking of americium relative to plutonium.