The two focuses of this project were to: 1. Verify two methods of chronic toxicity tests that using algae Selenastrum capricornutum and daphnid Daphnia magna to be tested organisms, and 2. Developing a test method for chronic toxicity of fish. In this project, the organism was tested with 5 reference toxicants and 5 environmental samples (river A and B, and industrial discharge water C, D, and E) to determine the chronic toxicities. The tested organisms included freshwater algae Pseudokirchneriella subcapitata, daphnid Daphnia magna, and carp, Cyprinus carpio. For test of algae, copper sulfate was used as a reference toxicant, and the 96-hr half-inhibitory concentration (IC50) was 61.61 g/L in average with standard deviation of 8.82 g/L. The IC50 of the 5 water samples on the algae were >100%, >100%, 19%, 42% and > 100% as dilution ratios. In addition, sodium chloride was used as a reference toxicant for daphnid, and the 21-d median lethal concentration (LC50) was 2.88 g/L in average with standard deviation of 0.61 g/L; 25% reproduction inhibitory concentration (IC25) was 1.62 g/L in average with standard deviation of 1.40 g/L; IC50 was 2.24 g/L with standard deviation of 1.28 g / L. The chronic toxicities of the 5 environmental samples to the daphnids were listed as following: LC50 >100%, 55.9%, 12.1%, 100%, and 47.2%; IC25 were >100%, 81.7%, 8.3%, 59.7% and >100%; IC50 were > 100%, 100%, 11.8%, 100% and 100%. Moreover, sodium chloride was also used as a reference toxicant for carp, and the 14-d LC50 were 6.84 g/L in average with standard deviation of 0.33 g/L; IC50 was 0.94 g/L in average with standard deviation of 0.56 g/L. The chronic toxicities of the five environmental samples were: LC50, >100%, 100%, 100%, 56.1%, and 100%; IC50, > 100%, 43.9%, 100%, 4.9%, and >100%. Besides, chronic toxicity on embryo of medaka fish was also evaluated. In the study, copper sulfate was used as a reference toxicant, and the LC50 was 0.21 mg/L in average with standard deviation of 0.06 mg/L. Based on the tested results, we proposed a few recommendations for modification of the test methods for the microalgae and the daphnia. The draft of chronic test for carp was also given in this report.

Aquatic organism, Chronic Toxicity，Median Lethal Concentration (LC50)