Biofouling and Biofilm Processes Section, Water and Steam Chemistry Division, Bhabha Atomic Research Centre, Kalpakkam 603102, India.
Biofouling and Biofilm Processes Section, Water and Steam Chemistry Division, Bhabha Atomic Research Centre, Kalpakkam 603102, India; Homi Bhabha National Institute, Anushakti Nagar, Mumbai 400094, India.
Ecotoxicol Environ Saf. 2017 Oct;144:97-106. doi: 10.1016/j.ecoenv.2017.06.001. Epub 2017 Jun 9.
Antifouling biocides are commonly used in coastal electric power stations to prevent biofouling in their condenser cooling systems. However, the environmental impact of the chemical biocides is less understood than the thermal stress effects caused by the condenser effluents. In this study, Chaetoceros lorenzianus, a representative marine diatom, was used to analyse the toxicity of two antifouling biocides, chlorine and chlorine dioxide. The diatom cells were subjected to a range of concentrations of the biocides (from 0.05 to 2mg/L, as total residual oxidants, TRO) for contact time of 30min. They were analysed for viability, genotoxicity, chlorophyll a and cell density endpoints. The cells were affected at all concentrations of the biocides (0.05-2mg/L), showing dose-dependent decrease in viability and increase in DNA damage. The treated cells were later incubated in filtered seawater devoid of biocide to check for recovery. The cells were able to recover in terms of overall viability and DNA damage, when they had been initially treated with low concentrations of the biocides (0.5mg/L of Cl or 0.2mg/L of ClO). Chlorophyll a analysis showed irreparable damage at all concentrations, while cell density showed increasing trend of reduction, if treated above 0.5mg/L of Cl and 0.2mg/L of ClO. The data indicated that in C. lorenzianus, cumulative toxic effects and recovery potential of ClO up to 0.2mg/L were comparable with those of Cl, up to 0.5mg/L concentration in terms of the studied endpoints. The results indicate that at the biocide levels currently being used at power stations, recovery of the organism is feasible upon return to ambient environment. Similar studies should be carried out on other planktonic and benthic organisms, which will be helpful in the formulation of future guidelines for discharge of upcoming antifouling biocides such as chlorine dioxide.
防污杀生剂常用于沿海火力发电厂的冷凝器冷却系统，以防止生物污垢。然而，与冷凝器废水造成的热应激影响相比，人们对化学杀生剂的环境影响了解较少。在这项研究中，使用了一种代表性的海洋硅藻角毛藻来分析两种防污杀生剂——氯气和二氧化氯的毒性。将硅藻细胞暴露于一系列杀生剂浓度（总残留氧化剂（TRO）为 0.05 至 2mg/L）下 30 分钟。分析了细胞活力、遗传毒性、叶绿素 a 和细胞密度等终点。所有杀生剂浓度（0.05-2mg/L）都对细胞产生了影响，表现出活力降低和 DNA 损伤增加的剂量依赖性。随后，将处理过的细胞在不含杀生剂的过滤海水中孵育，以检查其恢复情况。当最初用低浓度杀生剂（0.5mg/L 的 Cl 或 0.2mg/L 的 ClO）处理时，细胞在整体活力和 DNA 损伤方面都能够恢复。叶绿素 a 分析表明，在所有浓度下均造成不可修复的损伤，而细胞密度在处理浓度高于 0.5mg/L 的 Cl 和 0.2mg/L 的 ClO 时呈现出降低的趋势。数据表明，在角毛藻中，ClO 累积毒性效应和恢复潜力高达 0.2mg/L，与 Cl 高达 0.5mg/L 浓度时的研究终点相当。结果表明，在目前电站使用的杀生剂水平下，当生物返回环境时，其恢复是可行的。应该对其他浮游生物和底栖生物进行类似的研究，这将有助于制定未来二氧化氯等新型防污杀生剂的排放指南。
