State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China.
College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China.
Toxins (Basel). 2017 Sep 27;9(10):306. doi: 10.3390/toxins9100306.
blooms have become a ubiquitous phenomenon in freshwater ecosystems, and the size of colonies varies widely throughout the year. In the present study, hydrogen peroxide (H₂O₂) was applied to test the effect of this algaecide on colonies of different sizes and to evaluate the colonies' antioxidant strategy. The results showed that populations collapsed under treatment with 5 mg/L H₂O₂ at colony sizes smaller than 25 μm. A dosage of 20 mg/L H₂O₂ was necessary to efficiently control colonies larger than 25 μm. The enzymatic and non-enzymatic antioxidant systems of different colonies exhibited various strategies to mitigate oxidative stress. In small colonies, superoxide dismutase (SOD) activity was readily stimulated and operated with catalase (CAT) activity to eliminate reactive oxygen species (ROS). In colonies larger than 25 μm, the antioxidant enzyme CAT and antioxidant substance glutathione (GSH) played major roles in mitigating oxidative stress at H₂O₂ concentrations below 20 mg/L. In addition, application of the algaecide led to the release of intracellular-microcystins (MCs), and oxidatively-driven MCs reached high concentrations when colony size was larger than 100 μm. Algaecide control measures should be implemented before the formation of large colonies to limit the algaecide dosage and MC release.
水华已成为淡水生态系统中普遍存在的现象，其群体大小全年变化幅度很大。在本研究中，使用过氧化氢（H₂O₂）来测试这种杀藻剂对不同大小群体的影响，并评估群体的抗氧化策略。结果表明，在群体大小小于 25 μm 的情况下，用 5 mg/L H₂O₂ 处理会导致种群崩溃。要有效控制大于 25 μm 的群体，则需要 20 mg/L H₂O₂。不同群体的酶和非酶抗氧化系统表现出各种减轻氧化应激的策略。在小群体中，超氧化物歧化酶（SOD）活性很容易被刺激，并与过氧化氢酶（CAT）活性一起消除活性氧（ROS）。在大于 25 μm 的群体中，在 20 mg/L 以下的 H₂O₂浓度下，抗氧化酶 CAT 和抗氧化物质谷胱甘肽（GSH）在减轻氧化应激方面发挥主要作用。此外，杀藻剂的应用导致细胞内微囊藻毒素（MCs）的释放，当群体大小大于 100 μm 时，氧化驱动的 MCs 达到高浓度。应在大群体形成之前采取杀藻剂控制措施，以限制杀藻剂用量和 MC 释放。
