Radioactive tracer Application in Oceanographic Study in North - PowerPoint PPT Presentation

Radioactive tracer Application in Oceanographic Study in North Atlantic- Baltic Sea Jixin Qiao DTU-Nutech 1 25-04-2014

Nuclear properties of important U isotopes Nuclide Half-life, Decay Method of Abundance, % y mode production 232 U 68.9 trace α 232 Th( α , 4n) 233 Pa β - decay 233 U 1.59 × 10 5 trace α 234 U 2.46 × 10 5 0.0059-0.0050 α nature 235 U 7.04 × 10 8 0.7202-0.7198 α nature 235 U(n, γ ) 236 U 2.34 × 10 7 trace α 238 U(n,3n) 240 Pu α decay 238 U 4.47 × 10 9 99.2752-99.2739 α nature 2 DTU Nutech, Technical University of Denmark 25-04-2014

236 U sources in the environment Production/ Source term Amount Pathway Uranium Ore Neutron capture 1.5 kg Rock (0-1000 m) Neutron capture 22 kg Natural Earth Crust Surface Thermal neutron 10 kg Ocean Rock weathering 0.5 kg SUM 34 kg Direct atmospheric release Global fallout 900 kg and growth of 240 Pu Nuclear reactor Neutron activation 10 6 kg Anthropogenic Nuclear accidents & Small fraction Release/discharge reprocessing plants of reactor 236 U SUM 10 6 kg Steier et al. Nucl. Instr. Meth. In Phys. Res. B 2008, 266, 2246-2250. Christl et al. Geochim. Cosmochim. Acta 2012, 77, 98-107. 3 DTU Nutech, Technical University of Denmark 25-04-2014

Importance of 236 U • Geologic study : uranium prospecting, dating, erosion study • Nuclear safeguards : identify uranium source, trace uranium contamination from nuclear fuel or waste, reprocessing activities, hot cell facilities, production of medical radioisotopes • Hydrology and oceanography study : water mass movement, geochemical processes • Astronomy : a marker of supernova debris 4 DTU Nutech, Technical University of Denmark 25-04-2014

Typical levels of 236 U in the environment Location 236 U/ 238 U ratio 1 × 10 -14 - 5 × 10 -14 Rock 10 -12 - 10 -10 Uranium ore 10 -9 -10 -10 Atlantic Ocean 5 × 10 -9 - 22 × 10 -9 North Sea Japan Sea 10 -9 2 × 10 -8 - 1 × 10 -7 Soil in Ichikawa, Japan 2 × 10 -7 - 4 × 10 -7 Soil 200 km from Chernobyl power plant 10 -6 - 10 -3 Soil from the close vicinity of Chernobyl power plant 10 -7 - 10 -3 Depleted uranium (DU) contaminated areas in Kosovo 10 -6 - 10 -4 Uranium processing factories, USA 10 -6 - 10 -5 Irish Sea sediment (affected by Sellafield reprocessing plant) Commercial reagents and artificial standard materials 10 -6 Steier et al. Nucl. Instr. Meth. In Phys. Res. B 2008, 266, 2246-2250. Skaguchi et al. Sci. Total Environ. 2009, 407, 4238-4242. Christl et al. Nucl. Instr. Meth. In Phys. Res. B 2013, 294, 530-536 and 2008, 266, 2246-2250. 5 DTU Nutech, Technical University of Denmark 25-04-2014

Analytical procedure overview Take 0.5 mL sample, add 5 ng In, ICP-MS diluted to 5 mL with 0.5 M HNO 3 10 L filtrated measurement seawater for 238 U Add 10 ml conc. HNO 3 , 10 mL 0.1g/mL Fe, N 2 bubbling 10 min. Add 10% NH 3 ·H 2 O to pH 9, Siphon supernatant and centrifuge remaining slurry Supernatant Precipitate Add 20 mL conc.HNO 3 , digest under 200˚C for 2h. Evaporate to near dryness Discard Precipitate Dissolve with 15 mL 3 M HNO 3 Sample solution ca. 30 mL 1.Load the sample U 2.Wash with 40 mL 3 M HNO 3 T 3.Wash with 20 ml 6 M HCl E 4.Elute U with 10 mL 0.025 M HCl V A Wash with 2 × 10 mL H 2 O, Add 3 mg Fe, 10% NH 3 ·H 2 O AMS to pH9, centrifuge Dry, ash, mix with Ag powder measurement U eluate Precipitate for 236 U/ 238 U Qiao et al. Analytical Chemistry 2015, 87, 7411-7417. 6 DTU Nutech, Technical University of Denmark 25-04-2014

Tracer application of 236 U along Danish coast Kattegat North Sea Roskilde Fjord Jutland Zealand Baltic Sea 7 DTU Nutech, Technical University of Denmark 25-04-2014

b) a) b) a) c) d) c) d) a) 2013 surface, b) 2013 bottom, c) 2014 surface, d)2014 bottom 8 DTU Nutech, Technical University of Denmark 25-04-2014

Tracer application of 236 U in Baltic Sea Sampling year 2015 9 DTU Nutech, Technical University of Denmark 25-04-2014

129 I in the Baltic Sea and Kattegat (April 2007) Surface Deep water water DTU Nutech, Technical University of Denmark 10 Yi, Hou et al. ES&T 2011

Speciation of 127 I and 129 I in surface water in the Baltic Sea 127 I - / 127 IO 3 - 129 I - / 129 IO 3 - DTU Nutech, Technical University of Denmark

Depth profiles of 129 I in the Baltic Sea 129 I (10 8 atoms/L) Salinity 2007 200 30 7 6 20 100 5 10 b a 0 0 2006 30 200 8 7 15 6 13 20 9 100 14 5 12 11 3 10 10 4 1 2 c d 0 0 DTU Nutech, Technical University of Denmark

Tracer application along Greenland coast Sampling year 2013 Sampling year 2012 13 DTU Nutech, Technical University of Denmark 25-04-2014

Thank you! 14 DTU Nutech, Technical University of Denmark 25-04-2014