Distribution of radiocarbon in sediments of the cooling pond of RBMK type Ignalina Nuclear Power Plant in Lithuania.

The vertical distribution of radiocarbon (14C) was examined in the bottom sediment core, taken from Lake Drūkšiai, which has served as a cooling pond since 1983 for the 26 years of the Ignalina Nuclear Power Plant (INPP) operation using two RBMK-1500 reactors (Russian acronym for"Channelized Large Power Reactor"). 14C specific activity was measured in alkali-soluble and -insoluble fractions of the sediment layers. Complementary measurements of the 210Pb and 137Cs activity of the samples provided the possibility to evaluate the date of every layer formation, covering the 1947-2013 period. In addition, 14C distribution was examined in the scales of pelagic fish caught between 1980 and 2012. Our measurements reveal that, during the period 1947-1999, the radiocarbon specific activity in both fractions exhibits a parallel course with a difference of 5 ± 1 pMC (percent of modern carbon) being higher in alkali-soluble fraction, although 14C specific activity in both fractions increased by 11.4-13.6 pMC during the first 15 years of plant operation. However, during the 2000-2009 period, other than previously seen, a dissolved inorganic carbon (DIC) → aquatic primary producers → sediments 14C incorporation pattern occurred, as the radiocarbon specific activity difference between alkali-soluble and -insoluble fractions reached 94, 25, and 20 pMC in 2000, 2006, and 2008, respectively. Measurements in different sediment fractions allowed us to identify the unexpected organic nature of 14C contained in liquid effluences from the INPP in 2000-2009. The discrepancy between 14C specific activity in fish scales samples and DIC after 2000 also confirmed the possibility of organic 14C contamination. Possible reasons for this phenomenon might be industrial processes introduced at the INPP, such as the start of operation of the cementation facility for spent ion exchange resins, decontamination procedures, and various maintenance activities of reactor aging systems and equipment

Determination of129I in Arctic snow by a novel analytical approach using IC-ICP-SFMS

The environmental radiation background has increased in the last century due to human nuclear activities and in this context I-129 may be used to evaluate the anthropogenic contribution to global nuclear contamination. We present a fast and novel method for iodine-129 measurements. Coupling ion chromatography and inductively coupled plasma sector field mass spectrometry (IC-ICP-SFMS) allows the determination of iodine-129 at picogram per gram levels. The capability of the Dionex IONPAC (R) AS16 column to retain iodine species in the absence of NaOH has been used to pre-concentrate 5 mL samples. Although I-129 suffers from isobaric spectral interference due to the presence of Xe-129, the IC-ICP-SFMS technique allows I-129 to be determined by removing all other isobaric interferents. Furthermore, the Xe-129 interference is sufficiently small and stable to be treated as a background correction. This strategy permits the evaluation of I-129 speciation at sub-picogram per gram levels with a limit of detection (LOD) of 0.7 pg g(-1). Thus the range of possible applications of this technique is expanded to low-concentration environmental samples such as polar snow. Preliminary results obtained from Greenland (NEEM) snow pit samples confirm its applicability in environmental research