Occurrence of toxic cyanobacterial blooms in natural freshwaters could impair drinking water quality. Chlorine was often employed as an oxidant to treat algal-laden source waters in drinking water treatment plants. However, previous studies only focused on high-viability cyanobacteria at exponential phase. Whether the change of cell-viability of cyanobacteria could affect chlorination was unknown. Here, high- and low-viability Microcystis were collected from a whole life cycle of cyanobacteria in lab-scale, and effects of chlorination on membrane integrity and toxin fate of high- and low-viability Microcystis were subsequently investigated. Results showed chlorine exposure was lower for low-viability cells than high-viability cells with the same initial chlorine dosage, but low-viability cells were less resistant to chlorination, leading to higher rate of membrane damage (kloss) and intracellular toxin release (ki). For high-viability cells, there was no increase of extracellular toxin with sufficient chlorine exposure whereas it showed a continuous increase for low-viability cells mainly due to its lower rate of extracellular toxin degradation (ke, 26 ± 8 M-1 s-1) than intracellular toxin release (ki, 110 ± 16 M-1 s-1) (ke < ki). Besides, total toxin could be completely oxidized for high-viability cells with sufficient chlorine exposure (>30 mg min L-1) whereas chlorination could not work well for low-viability cells even with chlorine exposure of as high as 36 mg min L-1. These findings indicated chlorination may not be a feasible option to treat low-viability cyanobacteria during decline stage of cyanobacterial blooms.

中文翻译：

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比较氯化对高生存力和低生存力蓝细菌的膜完整性和毒素命运的影响。

天然淡水中出现有毒的蓝藻水华会损害饮用水的质量。在饮用水处理厂中，经常使用氯作为氧化剂来处理含藻源水。但是，以前的研究仅关注指数期的高生存力蓝细菌。蓝细菌细胞活力的变化是否会影响氯化反应尚不清楚。在这里，在实验室规模上从蓝细菌的整个生命周期中收集了高和低生存力的微囊藻，然后研究了氯化对高和低生存力的微囊藻的膜完整性和毒素命运的影响。结果显示，与相同初始氯剂量的高活力电池相比，低活力电池的氯暴露较低，但低活力电池的耐氯化性较弱，导致更高的膜损伤率（kloss）和细胞内毒素释放率（ki）。对于高存活力的细胞，暴露于足够的氯气不会增加细胞外毒素，而对于低存活力的细胞则显示出持续增加，这主要是由于其较低的细胞外毒素降解速率（ke，26±8 M-1 s-1 ）比细胞内毒素释放（ki，110±16 M-1 s-1）（ke <ki）。此外，对于具有足够氯暴露量（> 30 mg / min L-1）的高活力细胞，总毒素可以被完全氧化，而对于低活性细胞，即使氯暴露量高达36 mg / min L-，氯化也不能很好地起作用。 1。这些发现表明，在蓝藻水华衰落阶段，氯化可能不是治疗低生存力蓝藻细菌的可行选择。