Centro Nacional de Aceleradores (CNA), Accelerator Mass Spectrometry Unit, Avenida Tomas Alva Edison 7, Isla de Cartuja, Seville, Spain.
J Environ Radioact. 2011 Feb;102(2):200-5. doi: 10.1016/j.jenvrad.2010.11.014. Epub 2010 Dec 21.
Lichen is a symbiosis between algae and fungi. They have for decades been used as bioindicators for atmospheric deposition of heavy metals, organic compounds and radioactive elements. Especially the species Cladonia alpestris and Cladonia rangiferina are important for the food chain lichen-reindeer-man. The concentration of (129)I was determined in lichen samples (Cladonia alpestris) contaminated by fallout from atmospheric nuclear tests explosions and the Chernobyl accident. The samples were collected at Lake Rogen District (62.3°N, 12.4°E) in central Sweden in the periods 1961-1975 and 1987-1998, and analysed with accelerator mass spectrometry (AMS) at CNA (Seville) to study its distribution in different layers. Data on the (137)Cs activity measured previously were also included in this study. The (129)I concentration ranged from (0.95 ± 0.13) × 10(8) at g(-1) in 1961 in the uppermost layer to (14.2 ± 0.5) × 10(8) at g(-1) in 1987 in deepest layer. The (129)I/(137)Cs atom ratio ranged between 0.12 and 0.27 for lichen samples collected in the period 1961-1975, indicating weapons tests fallout. For lichen samples collected between 1987 and 1998 the behaviour of (137)Cs concentrations reflected Chernobyl fallout. The concentrations of the two radionuclides followed each other quite well in the profile, reflecting the same origin for both. From the point of view of the spatial distribution in the lichen, it appears that (129)I was predominantly accumulated in the lowest layer, the opposite to (137)Cs for which the highest amounts were detected systematically in the topmost layer of lichen. This vertical distribution is important for radioecology because lichen is the initial link in the food chain lichen-reindeer-man, and reindeer only graze the upper parts of lichen carpets.
地衣是藻类和真菌的共生体。几十年来，它们一直被用作大气重金属、有机化合物和放射性元素沉降物的生物指标。特别是 Cladonia alpestris 和 Cladonia rangiferina 这两个物种对食物链中的地衣-驯鹿-人类至关重要。本研究测定了受大气核试验爆炸和切尔诺贝利事故沉降物污染的地衣（Cladonia alpestris）样本中（129）I 的浓度。这些样本于 1961-1975 年和 1987-1998 年期间在瑞典中部罗根地区（62.3°N，12.4°E）采集，并用加速器质谱法（AMS）在 CNA（塞维利亚）进行分析，以研究其在不同层中的分布。本研究还包括之前测量的（137）Cs 活度数据。1961 年最上层的（129）I 浓度为（0.95±0.13）×10（8）at g（-1），1987 年最下层的（129）I 浓度为（14.2±0.5）×10（8）at g（-1）。1961-1975 年采集的地衣样本中（129）I/（137）Cs 原子比在 0.12 到 0.27 之间，表明这是武器试验沉降物。1987-1998 年采集的地衣样本中（137）Cs 浓度的行为反映了切尔诺贝利沉降物。在剖面中，两种放射性核素的浓度非常吻合，表明它们具有相同的来源。从地衣中（129）I 的空间分布来看，它主要积累在最低层，而（137）Cs 则相反，其最高浓度系统地分布在地衣的最上层。这种垂直分布对于放射生态学很重要，因为地衣是食物链地衣-驯鹿-人类的初始环节，而驯鹿只在地衣地毯的上层觅食。
