Department of Zoology, Guru Nanak Dev University, Amritsar, Punjab, 143005, India.
Department of Zoology, Khalsa College, Amritsar, Punjab, 143002, India.
Environ Sci Pollut Res Int. 2019 Jun;26(17):17121-17134. doi: 10.1007/s11356-019-05067-4. Epub 2019 Apr 18.
High contents of azo dyes and heavy metals enter surface waters with the wastewater from dying and dye-manufacturing industries and pose serious threat to fish. In the present study, changes in the ultra-morphological features of the scale have been evaluated as indicators of the stress of lethal and sublethal concentrations of an azo dye Acid Black-1 (AB-1, CI 20470), zinc (Zn), and their mixture AB-1 + Zn to Labeo rohita. Fish were exposed for 96 h to lethal concentration (LC) causing 0-70% mortality, i.e., LC, LC, LC, and LC of AB-1 (4, 6, 8, and 10 mg/L respectively) and Zn (25, 50, 55, and 60 mg/L respectively) and LC, LC, and LC of AB-1 + Zn (2 + 15, 2 + 20, and 2 + 25 mg/L respectively). Subchronic exposures of 150 days were given to 1/12, 1/6, and 1/3 of 96 h LC values of AB-1, Zn, and AB-1 + Zn. After each exposure, the fish were kept for a recovery period of 90 days. Breakage of circuli, erosion and breakage of lepidonts, uprooting of tubercles, and disappearance of intercircular teeth were observed in all the fish, after 96 h exposure to AB-1, Zn, and AB-1 + Zn. However, damage to focus and holes were common on the scales of Zn-exposed fish. The mixture AB-1 + Zn was more toxic than either of the two as loss of circuli, lepidonts, and intercircular teeth, and sloughing of surface were observed in the scales after 96 h exposure to 2 + 25 mg/L. Damage at this concentration was more than the damage at 8/10 mg/L AB-1 and 55/60 mg/L Zn. After 150 days of exposure, damage due to sublethal concentrations was more than the damage due to all the concentrations of 96 h exposure. Irregular and sloughed circuli were common at 2 + 1.79 and 2 + 3.59 mg/L AB-1 + Zn. Cracks all over the surface (2 + 7.18 mg/L), calcium projections (2 + 3.59 and 2 + 7.18 mg/L), and holes (2 + 7.18 mg/L) hint towards synergistic toxicity of the mixture. It seems that the present dye and metal formed complexes with collagen and osteoblastic cells of the scale that caused an increase in damage during the post-exposure period. Scales of 2 + 7.18 mg/L AB-1 + Zn exposed fish were completely devoid of the normal architectural pattern on the 90th day of the recovery period. Changes in the ultra-morphology of scales at LC (0% mortality) and sublethal concentrations show that these are early indicators of the stress of minute quantities of dyes and metals in water. This is a first report on the cumulative toxicity of the two most abundant components of textile industry effluents.
高浓度的偶氮染料和重金属随印染和染整工业废水进入地表水体，对鱼类构成严重威胁。在本研究中，评估了鳞片超形态特征的变化，作为致死浓度和亚致死浓度的偶氮染料酸性黑 1（AB-1，CI 20470）、锌（Zn）以及它们的混合物 AB-1+Zn 对罗非鱼（Labeo rohita）应激的指标。鱼在 96 小时内暴露于致死浓度（LC）下，导致 0-70%的死亡率，即 AB-1 的 LC、LC、LC 和 LC（分别为 4、6、8 和 10 mg/L）和 Zn（分别为 25、50、55 和 60 mg/L）和 AB-1+Zn 的 LC、LC 和 LC（分别为 2+15、2+20 和 2+25 mg/L）。150 天的亚慢性暴露于 AB-1、Zn 和 AB-1+Zn 的 96 小时 LC 值的 1/12、1/6 和 1/3。每次暴露后，鱼都要经过 90 天的恢复期。在 AB-1、Zn 和 AB-1+Zn 的 96 小时暴露后，所有鱼的鳞片都出现了轮纹断裂、珐琅质侵蚀和断裂、结节松动和环间牙齿消失。然而，Zn 暴露鱼的鳞片上常见焦点和孔的损伤。混合物 AB-1+Zn 比两种染料更具毒性，因为在 2+25 mg/L 暴露 96 小时后，观察到轮纹、珐琅质和环间牙齿丢失以及表面脱落。在这个浓度下的损伤比 8/10 mg/L AB-1 和 55/60 mg/L Zn 的损伤更严重。150 天暴露后，亚致死浓度的损伤比 96 小时所有浓度的损伤更严重。不规则和脱落的轮纹在 AB-1+Zn 的 2+1.79 和 2+3.59 mg/L 处很常见。整个表面的裂缝（2+7.18 mg/L）、钙突（2+3.59 和 2+7.18 mg/L）和孔（2+7.18 mg/L）表明混合物具有协同毒性。似乎目前的染料和金属与鳞片的胶原蛋白和成骨细胞形成复合物，导致在暴露后期间增加损伤。在恢复期第 90 天，AB-1+Zn 暴露于 2+7.18 mg/L 的鱼的鳞片完全没有正常的结构模式。LC（0%死亡率）和亚致死浓度下鳞片的超形态变化表明，这些是水中微量染料和金属应激的早期指标。这是关于纺织工业废水两种最丰富成分累积毒性的首次报告。
