Jeffree Ross A, Oberhansli Francois, Teyssie Jean-Louis
IAEA Marine Environment Laboratories, Radioecology Laboratory, 4 Quai Antoine 1er, MC 98000, Monaco.
Mar Pollut Bull. 2007 Jul;54(7):912-20. doi: 10.1016/j.marpolbul.2007.03.005. Epub 2007 Apr 27.
An experimental study examined the 96-h net influx from seawater of the anthropogenic radionuclides (241)Am, (60)Co and (134)Cs through the egg-case of the spotted dogfish Scyliorhinus canicula. Net influx directly through the wall of the egg-case was greatest for (134)Cs, then (241)Am and lastly (60)Co. Within the egg-case wall itself the measured concentration factors (CFs) and their gradients in the external, median and internal layers showed that for both (241)Am and (60)Co they were >10(3) in the external layer and declined by an order of magnitude in the interior layer. In contrast (134)Cs had a CF of only about three in the external layer which declined by a factor of 2 towards the two more internal layers of the egg-case. The egg-case apertures, that open within the prehatching stage of embryological development, significantly (P<0.05) increased the net influx of (241)Am and (60)Co to the interior of the egg-case, although their water concentrations were still lower than those in the labelled seawater bath. In contrast, the aperture did not increase the net influx of (134)Cs whose water concentrations equilibrated with those in seawater. Together these results indicate that the egg-case wall is very permeable to (134)Cs, representing little barrier to its movement, and hence consistent with the lack of importance of the aperture in determining its internal water concentrations in the egg-case. In contrast, (241)Am and (60)Co show much higher rates of accumulation by the egg-case, consistent with the measured reduced permeability of its wall, and therefore giving greater prominence to its aperture in the net transfer of these two radionuclides to the egg case's interior. The presence of the embryo within its egg-case did not significantly (P>0.05) affect the rates of influx of radioisotopes, with the exception of an interactive effect for (60)Co with the egg-case aperture (P<0.05). The CF of only (241)Am in the embryo itself relative to the external seawater concentration was significantly (P<0.05) enhanced by the presence of the aperture.
一项实验研究检测了人为放射性核素镅 - 241、钴 - 60和铯 - 134在96小时内通过斑点角鲨（Scyliorhinus canicula）卵鞘从海水中的净流入量。直接通过卵鞘壁的净流入量，铯 - 134最大，其次是镅 - 241，最后是钴 - 60。在卵鞘壁本身内部，测量的浓缩系数（CFs）及其在外层、中层和内层的梯度表明，对于镅 - 241和钴 - 60，它们在外层均大于10³，在内层下降了一个数量级。相比之下，铯 - 134在外层的浓缩系数仅约为3，朝着卵鞘的另外两层内层下降了2倍。在胚胎发育的孵化前阶段打开的卵鞘孔显著（P<0.05）增加了镅 - 241和钴 - 60向卵鞘内部的净流入量，尽管它们在水中的浓度仍低于标记海水浴中的浓度。相比之下，卵鞘孔并没有增加铯 - 134的净流入量，其在水中的浓度与海水中的浓度达到了平衡。这些结果共同表明，卵鞘壁对铯 - 134具有很高的渗透性，对其移动几乎没有阻碍，因此这与卵鞘孔在决定其内部水中浓度方面的不重要性是一致的。相比之下，镅 - 241和钴 - 60在卵鞘中的积累速率要高得多，这与其壁的测量渗透率降低相一致，因此在这两种放射性核素向卵鞘内部的净转移中，卵鞘孔的作用更加突出。卵鞘内胚胎的存在除了对钴 - 60与卵鞘孔有交互作用（P<0.05）外，对放射性同位素的流入速率没有显著（P>0.05）影响。卵鞘孔的存在显著（P<0.05）提高了胚胎本身中仅镅 - 241相对于外部海水浓度的浓缩系数。
