Kong Shengquan, Liu Xiaojing, Jiang Hongyu, Hong Wenjie, Zhang Jibiao, Song Weihua, Yan Shuwen
Department of Environmental Science & Engineering, Fudan University, Shanghai 200433, PR China.
Department of Environmental Science & Engineering, Fudan University, Shanghai 200433, PR China.
Water Res. 2023 Sep 1;243:120395. doi: 10.1016/j.watres.2023.120395. Epub 2023 Jul 21.
Algal organic matter (AOM), a significant source of endogenous dissolved organic matter (DOM) is released in high concentrations during cyanobacterial blooms, along with cyanotoxins. Subsequent photobleaching of AOM is an important phenomenon to investigate. In this study, intracellular organic matter (IOM) and extracellular organic matter (EOM) were extracted from cultured cyanobacteria taken from Taihu Lake in China. The formation of photochemically produced reactive intermediates in different stages of IOM and EOM photobleaching was compared to Suwannee River DOM (SRDOM, reference standard DOM). Results revealed notable differences influenced by the pigment component among IOM, EOM, and SRDOM. The pigment in IOM contributed to a triplet state pool with strong energy-transfer but limited electron-transfer capabilities. Notably, IOM exhibited the highest triplets state quantum yield value in the visible region, suggesting its potential significance in pollutant degradation in deeper water layers. For EOM, one of the pools exhibits photolability and remarkable electron-transfer capability, indicating it as a high-energy triplet state component. Moreover, three cyanotoxins (MC-LR, ACA, and ATX-a) were detected in the extracted AOM, and their photodegradation was monitored during the AOM photobleaching process. This highlights the potential role of AOM as a photosensitizer in the natural self-cleaning mechanisms of water bodies, facilitating the degradation of organic pollutants through photochemical reactions. The findings of this study contribute to understanding the dynamic nature of AOM and its implications in environmental processes.
藻类有机物（AOM）是内源性溶解有机物（DOM）的重要来源，在蓝藻水华期间会与蓝藻毒素一起高浓度释放。随后AOM的光漂白是一个值得研究的重要现象。在本研究中，从中国太湖采集的养殖蓝藻中提取了细胞内有机物（IOM）和细胞外有机物（EOM）。将IOM和EOM光漂白不同阶段光化学产生的反应中间体的形成与苏万尼河DOM（SRDOM，参考标准DOM）进行了比较。结果显示，IOM、EOM和SRDOM之间受色素成分影响存在显著差异。IOM中的色素促成了一个具有强大能量转移但电子转移能力有限的三重态池。值得注意的是，IOM在可见光区域表现出最高的三重态量子产率值，表明其在较深水层污染物降解中的潜在意义。对于EOM，其中一个池表现出光解性和显著的电子转移能力，表明它是一种高能三重态成分。此外，在提取的AOM中检测到三种蓝藻毒素（MC-LR、ACA和ATX-a），并在AOM光漂白过程中监测了它们的光降解。这突出了AOM作为水体自然自净机制中光敏剂的潜在作用，通过光化学反应促进有机污染物的降解。本研究结果有助于理解AOM的动态性质及其在环境过程中的影响。
