STUDY ON ACUTE TOXICITY OF MICROPLASTIC TO DAPHNIA MAGNA

In order to understand the impact of microplastics on the ecological environment of freshwater, we choose Daphnia magna as test organisms and studied the acute toxicity of PVC and recovery test of PVC. Seven groups of PVC concentration gradient and four repetition groups were set up. The range was 0—400 mg/L and the equivalence coefficient was 2. After 96h acute toxic exposure, the LC₅₀, heart rate and antioxidant index were determined. The recovery experiment without PVC for 21 days was also conducted. The 96-hour LC₅₀ was 130.132 mg/L, and the 95% confidence interval from 82.864 to 234.989 mg/L. Compared with the control group, the heart rate of the high concentration groups (50—200 mg/L) were significantly different (P<0.05), while the low concentration group had no significant difference (P>0.05); the ingestion rate of the high concentration groups (25—200 mg/L) had a significant difference (P<0.01), and the low concentration group had no significant difference (P>0.05); the SOD and GSH values of the high concentration group (200 mg/L) had significant differences (P<0.05), but the low concentration group had no significant difference (P>0.05). The first reproduction time was advanced, but the body length of the offspring became shorter and deformed. The number of deaths in the offspring of the treatment group was higher than that of the control group. The body length of the female was shortened than the control group. These results showed that D. magna exposed to PVC caused itself toxic injury, and short-term exposure would lead to adverse effects on the growth and reproduction of D. magna.