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Natural and artificial radionuclides in a marine core. First results of 236U in North Atlantic Ocean sediments
- Source :
- Digital.CSIC. Repositorio Institucional del CSIC, instname
- Publication Year :
- 2018
- Publisher :
- Elsevier, 2018.
-
Abstract
- There are very few data available of 236U in marine sediment cores. In this study we present the results from the first oceanic depth profile of 236U in a sediment core sampled in the North Atlantic Ocean, at the PAP site (4500 m depth, Porcupine Abyssal Plain (PAP) site, 49°0′ N, 16°30′ W). Additionally, the sediment core was radiologically characterized through the measurement of anthropogenic 137Cs, 239Pu, 240Pu, 129I and 14C and natural 210Pb, 40K and 226Ra. The measured 236U concentrations decrease from about 90·106 at g−1 at the seafloor down to 0.5·106 at g−1 at 6 cm depth. They are several orders of magnitude lower than the reported values for soils from the Northern Hemisphere solely influenced by global fallout (i.e. from 2700·106 to 7500·106 at g−1). 236U/238U atom ratios measured are at least three orders of magnitude above the estimated level for the naturally occurring dissolved uranium. The obtained inventories are 1·1012 at m−2 for 236U, 80 Bq m−2 for 137Cs, 45 Bq m−2 for 239+240Pu and 2.6·1012 at m−2 for 129I. Atomic ratios for 236U/239Pu, 137Cs/236U and 129I/236U, obtained from the inventories are 0.036, 0.11 and 2.5 respectively. Concentration profiles show mobilization probably due to bioturbation from the abundant detritivore holothurian species living at the PAP site sea-floor. The range of 236U, 137Cs, 239+240Pu and 129I values, inventories and ratios of these anthropogenic radionuclides are more similar to the values due to fall-out than values from a contribution from the Nuclear Fuel Reprocessing Plants dispersed to the south-west of the North Atlantic Ocean. However, signs of an additional source are detected and might be associated to the nuclear wastes dumped on the Eastern North Atlantic Ocean.<br />This work was partly supported by Spanish MINECO research project No. FIS2015-69673-P.
- Subjects :
- Radionuclide
010504 meteorology & atmospheric sciences
Nuclear fuel reprocessing plants
Health, Toxicology and Mutagenesis
Inventory
Northern Hemisphere
Detritivore
Sediment
General Medicine
010501 environmental sciences
Geologic Sediments
Sediment cores
01 natural sciences
Pollution
Seafloor spreading
Oceanography
Environmental Chemistry
Porcupine Abyssal Plain
Waste Management and Disposal
Bioturbation
Geology
0105 earth and related environmental sciences
Subjects
Details
- Language :
- English
- Database :
- OpenAIRE
- Journal :
- Digital.CSIC. Repositorio Institucional del CSIC, instname
- Accession number :
- edsair.doi.dedup.....0eef889356a692d20e7b027137e030c3