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

Based on acute toxicity data for freshwater species from China and the United States, species sensitivity distributions (SSDs) were developed to derive water quality criteria. Sensitivity to copper in taxa of vertebrates, invertebrates, fishes, arthropods, non-arthropod invertebrates and in all taxa were compared separately between species of China and the United States. The results suggest that under the 95% protection level, the sensitivity of various aquatic organisms in China to copper was in the order: arthropod > invertebrates > non-arthropod > fishes > vertebrates. With the same protection level, aquatic organisms in the United States were in the order: invertebrates > non-arthropod > arthropod > vertebrates > fishes. Based on the hazardous concentration at the 5th percentile of the species (HC₅) value for short-term exposure to copper, vertebrates, fish and arthropods are more sensitive in China than in the United States with the exception of non-arthropods and invertebrates. No significant differences were observed between sensitivity distributions derived for species in China and the United States except for non-arthropods. Therefore, in determining the water quality criteria based on the sensitivities of all species, we should also consider the influence of SSD of individual groups.