采用静水毒性试验法,模拟研究了电厂温排水对黑棘鲷(Acanthopagrus schlegelii)胚胎发育的影响.试验水温为16~18,22,26和30℃,ρ(余氯)为0.025,0.050,0.100,0.200,0.400和0.800 mg L,同时以过滤海水为对照组,每组设3个平行,取黑棘鲷受精卵进行试验,共进行30 h观测.结果表明,16~18℃下对照组无胚胎孵化,而在其他3个温度条件下,对照组的胚胎均已破膜并发育至前期仔鱼阶段.其中,22℃下对照组孵化率最高,为(93±2.0)%,而26和30℃下对照组孵化率分别为(81.9±2.0)%和(52.8±10.6)%.随着ρ(余氯)的升高,胚胎孵化率下降,当ρ(余氯)高于0.400 mg L时,各组孵化率均低于50%,当ρ(余氯)为0.800 mg L时,各组孵化率均低于10%,30℃组则没有胚胎孵化.回归分析结果显示,黑棘鲷胚胎孵化抑制率与水温和ρ(余氯)呈显著正相关(R=0.90,P〈0.05),表明这2种因子对胚胎孵化抑制具有协同毒性效应.经计算,30 h时22,26和30℃下,ρ(余氯)对黑棘鲷胚胎发育的半数影响浓度(30 h-EC50)分别为(0.243±0.062),(0.432±0.031)和(0.261±0.046)mg L,最低可观察效应浓度(LOEC)分别为0.025,0.200和0.050 mg L,26和30℃下无可观察效应浓度(NOEC)为0.100和0.025 mg L.
The lenitic toxicity test method was used to simulate the effects of thermal drainage from power plants on the embryonic development of Acanthopagrus schlegelii.Both water temperature and the amount of residual chlorine were the stressors to be tested.Four different water temperatures were set as 16-18,22,26 and 30℃,and six different gradients of residual chlorine concentration were set as 0.025,0.050,0.100,0.200,0.400 and 0.800 mgL.Each concentration had three parallel samples.At the same time,filtered seawater was taken as the control.Newly fertilized eggs of A.schlegelii were used as test samples.The results showed that the fertilized eggs had developed into the sac-fry stage after incubation for 30h at 22,26 and 30℃,and the exact hatching rates were 93%±2.0%,81.9%±2.0% and 52.8%±10.6%,respectively.However,the fertilized eggs remained at the yolk-sac stage after incubation for 30h at 16-18℃.Further study showed that the hatching rate decreased with the elevated concentration of residual chloride.The hatching rates were below 50% for all groups when the concentration of residual chloride was higher than 0.400 mg L.When the concentration of residual chloride was higher than 0.800 mg L,the hatching rates were below 10% for all groups,and was zero for the 30 ℃ group.The inhibition rate of embryonic hatching was significantly and positively correlated with water temperature and residual chlorine concentration(R=0.90,P 0.05),which indicated that water temperature and residual chlorine had a synergistic toxic effect on the embryonic hatching.The half maximal effective concentration values of residual chlorine to the embryonic hatching rate of A.schlegelii after incubation for 30 h(30 h-EC50) were calculated to be(0.243±0.062),(0.432±0.031) and(0.261±0.046) mg L at 22,26 and 30 ℃,respectively.The lowest observed effect concentration(LOEC) values of residual chlorine to the embryonic hatching rate of the fish were determined to be 0.025,0.200 and 0.050 mgL at 22,26 and 30 ℃,res