Institute of Marine Research (IMR), PO Box 1870 Nordnes, N-5817 Bergen, Norway.
Sci Total Environ. 2010 Oct 15;408(22):5575-82. doi: 10.1016/j.scitotenv.2010.07.068.
The distribution of technetium-99 ((99)Tc) in annual growth segments of the brown seaweed Ascophyllum nodosum (Fucales, Phaeophyceae) from the southwestern coast of Norway is examined in samples collected from January to November 2006. A twenty-fold increase in the (99)Tc-concentration from the youngest to the oldest growth segments was found. The concentrations ranged from 42 to 98Bq/kg dry weight (d.w.) and from 964 to 1000Bq/kg d.w. in growth segments formed in 2006 and 1996, respectively. In addition, a seasonal variation in the (99)Tc concentration was observed in the actively growing 2006-segments: concentrations decreased from 98Bq/kg d.w. in April to 54Bq/kg d.w. in June; there was a further reduction from June to August (42Bq/kg d.w.); and, finally there was an increase from August to November (93Bq/kg d.w.). In most of the segments formed between 2000 and 2005, there was a tendency of slightly decreasing (99)Tc-concentrations between June and November but this pattern was not observed for the older growth segments. In order to find an explanation for the non-homogenous distribution of (99)Tc within thalli of A. nodosum, different hypotheses are discussed. Uptake and elimination of (99)Tc appears to be most pronounced in the actively growing segments. To date, such non-homogenous distribution of (99)Tc within thalli of A. nodosum has not been taken into consideration, neither in connection with sample collection nor analysis. This paper shows that special protocols must be followed if A. nodosum is going to be used as a bioindicator for (99)Tc in the marine environment. A sampling strategy is proposed.
本研究调查了 2006 年 1 月至 11 月期间采集于挪威西南海岸的褐藻龙须菜（Fucales，Phaeophyceae）中每年生长段的锝-99（Tc）分布。发现（99）Tc 浓度从最年轻的生长段到最老的生长段增加了二十倍。2006 年和 1996 年形成的生长段的浓度范围分别为 42 至 98Bq/kg 干重（d.w.）和 964 至 1000Bq/kg d.w.。此外，在活跃生长的 2006 年生长段中观察到（99）Tc 浓度的季节性变化：浓度从 4 月的 98Bq/kg d.w.下降到 6 月的 54Bq/kg d.w.；6 月至 8 月进一步下降（42Bq/kg d.w.）；最后，8 月至 11 月上升（93Bq/kg d.w.）。在 2000 年至 2005 年期间形成的大多数生长段中，6 月至 11 月（99）Tc 浓度有略微下降的趋势，但这种模式在较老的生长段中并未观察到。为了找到（99）Tc 在龙须菜体内不均匀分布的原因，本文讨论了不同的假设。在活跃生长的段中，（99）Tc 的吸收和消除似乎最为明显。迄今为止，在龙须菜的体内尚未考虑到（99）Tc 的这种不均匀分布，无论是在样本采集还是分析方面。本文表明，如果要将龙须菜用作海洋环境中（99）Tc 的生物标志物，必须遵循特殊的协议。本文提出了一种采样策略。
