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129I levels in soils from Ukraine and Slovenia in the last decade

Osterc, Andrej, Stibilj, Vekoslava
International journal of environmental analytical chemistry 2013 v.93 no.5 pp. 553-564
biogeochemical cycles, iodine, mixing, neutron activation analysis, pollution, soil, soil sampling, Slovenia, Ukraine
¹²⁹I is important as an environmental tracer of the biogeochemical cycling of iodine and of the dissemination of nuclear pollution, because anthropogenic ¹²⁹I has been released from only few point sources and with its short mixing time its distribution therefore reveals the movement of ¹²⁹I in the environment. A radiochemical neutron activation analysis method was developed to measure the concentration of ¹²⁹I in soil samples. A procedure to pre-concentrate iodine from up to 150 g of soil was developed and validated using IAEA standard reference material IAEA-375 (Chernobyl soil). The method was applied to determine ¹²⁹I/¹²⁷I isotopic ratios as well as ¹²⁹I and ¹²⁷I concentrations in soils from several locations in Ukraine collected in 2006, 1996, 1993 and 1989, and from Slovenia, collected at various places in 2009 and 2006. The ¹²⁷I concentrations in surface soils from Ukraine were in the range 2.3–23.1 µg g⁻¹ and for ¹²⁹I (11.1–245.7) · 10⁻⁸ µg g⁻¹ dry matter with the highest value of 1.47 · 10⁻³ µg g⁻¹ found in a soil sample collected in Yaniv, Ukraine in July 1993. In soil samples from Slovenia ¹²⁷I concentrations ranged 0.73–130 µg g⁻¹ and ¹²⁹I (8.0–245.7) · 10⁻⁸ µg g⁻¹. The ¹²⁹I/¹²⁷I isotopic ratios of surface soils from Ukraine were in the range of the order of 10⁻⁹–10⁻⁵ and of 10⁻¹⁰–10⁻⁸ for soils from Slovenia. The highest isotopic ratio 13.6 · 10⁻⁵ was found in a soil sample collected in Yaniv, Ukraine in July 1993.