Abstract: To assess the pollution and management effects of the black-odors rivers from Wenzhou, we screened the toxocity of aqueous sediment extracts and interstitial water of rivers using Xenopus tropicalis  embryos. The surface sediment samples were collected for 5 times from September to December in 2010. The embryos were exposed to the extracting solution of the sediments (1∶4) for the first to the fourth tests and in the interstitial water for the fifth test for 48 h. Our results showed that all the embryos treated with samples from S1 died after 48 h of exposure during the 5 tests. This suggested that the sediments in S1 showed very high toxicity. Compared with the control, the body length of embryos treated with aqueous sediments extracts from Shanxia River was significantly decreased, but the body length of embryos treated with those from Jiushan River was decreased only in the third test. The percent of malformations were higher in Shanxia River than that in Jiushan River. Especially, the percent of malforation was up to 100% in S2-S4, but the highest of percent of malformations was only 70% (J2) and 40 (J1) in Jiushan River. The interstitial water of sediments in Shanxia River led to the death of all embryos. These results suggested that the toxicity of sediments in Shanxia River was generally higher than that in Jiushan River, and that the interstitial water was more toxic than aqueous sediments extracts. Our study indicates that the sediments of the black-odors rivers have adverse effects on the development of X. tropicalis embryos and show significant ecological toxicity. In addition, X. tropicalis embryos can be used for screening the hazards of sediments effectively.

Key words: black-odors river, sediment, Xenopus tropicalis, embryos