Deriving freshwater quality criteria of sulphocyanic sodium for the protection of aquatic life in China

The freshwate quality criteria of sulphocyanic sodium (NaSCN) were studied on the basis of the features of the aquatic biota in China, and with reference to US EPA's guidelines. Acute tests were performed on twelve different domestic species to determine 48h-EC50/96h-EC50 (or 96h-LC50) values for NaSCN. 21d survival-reproduction test with Daphnia magna, 60d fry-juvenile part life stage test with Carassius auratus gibelio and 96h growth inhibition test with Lemna minor were also conducted to estimate lower chronic limit/upper chronic limit values. In the acute tests, D. magna was the most sensitive species to NaSCN followed by Tilapia mossambia, Cyprinus carpio and C. auratus gibelio in turn. The final acute value of NaSCN was 2.669 mg/L. In the chronic tests, reproduction and daphnids were significantly reduced by NaSCN at 1.0 mg/L. Acute-to-chronic ratios ranged from 5.96 to 19.1. A final chronic value of 0.2530 mg/L was obtained and a final plant was 1346 mg/L. A criterion maximum concentration (1.349 mg/L) and a criterion continuous concentration (0.2530 mg/L) were derived respectively. The results of this study may provide a useful data to derive national WQC for NaSCN as well as the procedure of deriving WQC of other chemicals for the protection of aquatic biota in China.