氨氮和亚硝酸盐对单环刺螠幼体的急性毒性实验

在水温15.1~17.3℃,pH 7.88~8.15,盐度32.17‰~32.28‰,溶解氧6.40~7.40 mg/L的条件下,采用半静水法研究了氨氮和亚硝酸盐对体质量(2.86±0.43)g的单环刺螠(Urechis unicinctus)幼体的急性毒性效应。试验结果表明,单环刺螠幼体中毒后体色变暗,对外界刺激变得不敏感,最后身体缩成一团或细线状。随着氨氮和亚硝酸盐质量浓度升高死亡率逐渐升高,存在明显的剂量效应和时间效应。氨氮对单环刺螠幼体96 h半致死质量浓度分别为620.79 mg/L(95%置信区间557.62~691.11 mg/L),安全质量浓度为62.08 mg/L,对应非离子氨浓度为13.85 mg/L(95%置信区间12.44~15.42 mg/L),安全质量浓度为1.39 mg/L;亚硝酸盐对单环刺螠幼体96 h半致死质量浓度为243.90 mg/L(95%置信区间223.10~266.65 mg/L),安全质量浓度为24.39 mg/L。非离子氨对单环刺螠幼体毒性大于亚硝酸盐毒性。

Acute toxicity test of ammonia nitrogen and nitrite on Urechis Unicinctus larva

Under the conditions of water temperature 15.1~17.3℃,pH 7.88~8.15,salinity 32.17‰~32.28‰,and dissolved oxygen 6.40~7.40 mg/L,the method of half static water was adopted to study the acute toxicity effects of ammonia nitrogen and nitrite on Urechis unicinctus larva with a body mass of(2.86+0.43)g.Test results showed that after being poisoned,the Urechis unicinctus larva got a darker body color and became less sensitive to external stimuli,eventually huddling itself into a ball or a fine line.With the increase of the mass concentration of ammonia nitrogen and nitrite,the lethality rate gradually increased,so it was apparent that there existed a dose effect and a time effect.As for the effects of ammonia nitrogen on the Urechis unicinctus larva,the 96 h lethal concentration 50(LC50)was 620.79 mg/L(95%confidence interval 557.62~691.11 mg/L)with a safety mass concentration of 62.08 mg/L,the corresponding non-ionic ammonia concentration was 13.85 mg/L(95%confidence interval 12.44~15.42 mg/L)with a safety mass concentration of 1.39 mg/L;as for the effects of nitrite on the Urechis unicinctus larva,the 96 h LC50 was 243.90 mg/L(95%confidence interval 223.10~266.65 mg/L)with a safety mass concentration of 24.39 mg/L.Non-ionic ammonia is more toxic to the Urechis unicinctus larva than nitrite.