Details

Autor(en) / Beteiligte

• Figueira, Rubens C L
• Tessler, Moyses G
• De Mahiques, Michel M
• Cunha, Ieda I L

Titel

Distribution of (137)Cs, (238)Pu and (239+240)Pu in sediments of the southeastern Brazilian shelf-SW Atlantic margin

Ist Teil von

• The Science of the total environment, 2006-03, Vol.357 (1-3), p.146-159

Erscheinungsjahr

2006

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• In this work levels of (137)Cs, (238)Pu and (239 + 24)Pu as well as activity ratios of anthrophogenic radionuclides in sediment samples from the southeastern Brazilian shelf are presented. Instrumental gamma spectrometry was used to determine (137)Cs and alpha spectrometry to determine (238)Pu and (239 + 240)Pu after a radiochemical procedure. The levels ranged from 0.30 to 1.79 Bq kg(-1) for (137)Cs, from 15 to 150 mBq kg(-1) for (238)Pu and, from 18 to 117 mBq kg(-1) for (239 + 240)Pu. There was a bathymetric differentiation in the radionuclides distribution. (137)Cs values were generally higher in the samples collected at water depths of less than 100 m. On the other hand, plutonium isotopes exhibit higher values at greater depths. The mean ratio of (239 + 240)Pu/(137)Cs obtained was 0.112 - 0.072 which is in agreement with the value reported for the Atlantic from atmospheric fallout of nuclear explosions in the past. The (238)Pu/(230 + 240)Pu ratios varied widely (from 0.339 to 2.088) and showed the influence of the SNAP-9A accident in the (238)Pu levels for this area. The main goal of this work was to present unpublished anthropogenic radionuclide levels and activity ratios related to the contamination of the southeastern Brazilian shelf.