中美淡水生物区系中汞物种敏感度分布比较

通过收集无机汞对中国与美国淡水水生生物的毒性数据,构建了脊椎动物(包括鱼类)、无脊椎动物(包括节肢动物和非节肢无脊椎动物)及所有物种对汞的物种敏感度分布(SSD:species sensitivity distributions)曲线,并在此基础上对中国和美国不同类别生物对汞的敏感性分布进行了分析.结果表明:中国与美国各类生物及所有物种对汞的SSD敏感性分布曲线没有显著差异.然而,中国淡水水生物种对汞短期暴露的HC5(hazardous concentration for 5% of the species)较美国淡水物种的阈值小,尤其是非节肢无脊椎动物,汞对美国非节肢动物的HC5值是我国对应物种的7.4倍.在保护95%的物种水平下,中国不同类别试验生物对汞的敏感性排序为无脊椎动物>脊椎动物,其中节肢动物>非节肢无脊椎动物>鱼类;而对应的美国生物对汞的敏感性排序无脊椎动物>脊椎动物,其中节肢动物>鱼类>非节肢无脊椎动物.另外,中美所有节肢动物对汞的敏感性要强于所有鱼类和所有非节肢无脊椎动物.所以在使用所有物种推导水质基准时应考虑其中各类别物种敏感度分布的影响,且需要注意采用美国淡水水生物种推导的水质基准可能会对我国淡水水生物种造成"保护不足".

Comparison of mercury species sensitivity distributions of freshwater biota in China and the United States

Based on single-species freshwater acute toxicity data in China and the United states, species sensitivity distributions (SSDs) of vertebrates (including fish) and invertebrates (including arthropods and non-arthropod invertebrates) to mercury were constructed, and species sensitivity to mercury in these two countries were compared. The results of this study indicated that there was no significant difference between sensitivity distributions of the Chinese and American taxa. However, the hazardous concentration for 5% of the species (HC₅) range of Chinese species to short-term mercury exposure was lower than that of the American species, especially for non-arthropod invertebrates. HC₅ for American non-arthropod invertebrates to mercury was 7.4 times larger than that for the corresponding Chinese species. Under the 95% protection level and including all the species, the tested invertebrates were more sensitive to mercury than the vertebrates in both China and the United States. However, in the lower taxonomic classification level, the sensitivity decreased in the order of arthropod > non-arthropod invertebrates > fish in China, but the order was arthropods > fish > non-arthropod invertebrates in the United States. Therefore, in determining the water quality criteria based on the sensitivity of all the species, we should also consider the influence of SSD of individual groups. The water quality criteria derived from the species sensitivity distribution of American species may make the aquatic species in China out of protection.