上海市河道的氮源污染物及其对食蚊鱼急性毒性的初步研究

Pollution and Acute Toxicity to the Mosquitofish of Ammonia and Nitrite Nitrogen in Urban Rivers of Shanghai

2008年6～8月对上海市内4条不同生态类型河道(午潮港、横港、朝阳河、曹杨环浜)的水质状况及鱼类组成进行调查。结果显示,除曹杨环浜外,所调查的其他3条河道普遍受氨氮污染,氨氮含量均超过了地表水环境标准Ⅴ类水的限值2.0mg/L;污染河道中鱼类种类极少,入侵鱼种食蚊鱼(Gambusia affinis)已成为其中的广布种。进一步选取上述调查河道中典型的氮类污染因子氨氮、亚硝酸盐作为暴露物,采用静水生物法对食蚊鱼进行96h急性毒性试验,发现食蚊鱼对氨氮的耐受性较高,24、48、72、96h的半致死浓度(LC50)分别为80.00、54.81、52.78、44.58mg/L;对亚硝酸氮的耐受性相对较低,24、48、72、96h的LC50分别为9.19、7.46、6.06、5.99mg/L。由于不同鱼类对环境污染物的耐受性和适应性不同,其种类组成易受河道污染程度影响,而食蚊鱼由于其对氨氮较高的耐受性,已成为上海各污染河道中的主要鱼种,进一步探讨其适应机制,将有助于了解河道生态类型的发展趋势及演变过程。

Investigation was conducted on the water quality and fish profile in four urban rivers of Shanghai during June and August 2008 , and the acute toxicity of ammonia and nitrite to mosquito fish （ Gambusia affinis） were determined using a static renewal method. The results showed that most of the rivers investigated were polluted by am- monia except for Caoyang River, and the concentrations of ammonia exceeded the Class-V standard as set in envi- ronment quality standards for surface water （ 2.0 mg/L NH3 - N ）. Few fish species in polluted rivers could be observed except G. affinis, which was the dominating fish in the polluted rivers; The LCs0 values of ammonia and nitrite to G. affinis at 24, 48, 72, 96 h were 80.00,54.81,52.78,44.58 mg/L and 9.19, 7.46, 6.06, 5.99 mg/L, respectively, indicating a higher tolerance ability to ammonia and a lower tolerance ability to nitrite. These results suggest that fish species compositions were easily affected by the pollutants due to different tolerance and adaptability, and G. affinis was the dominant fish species in the pollution rivers now for its high tolerance to ammonia, but the mechanism of accommodating to the ammonia pollution for this species need further being studed.