Xue Qingju, Kong Ming, Xie Liqiang, Li Tong, Liao Mengna, Yan Zebin, Zhao Yanyan
State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, 73 East Beijing Road, Nanjing, 210008, China.
University of Chinese Academy of Sciences, 19 Yuquan Road, Beijing, 100049, China.
Environ Sci Pollut Res Int. 2022 Dec;29(58):87132-87143. doi: 10.1007/s11356-022-21665-1. Epub 2022 Jul 8.
Harmful cyanobacterial blooms are increasing in frequency and severity, which makes their toxic secondary metabolites of microcystins (MCs) have been widely studied, especially in their distribution and influence factors in different habitats. However, the distribution of MCs on the early growth stage of harmful cyanobacteria and its influence factors and risks are still largely unknown. Thus, in the present study, two reservoirs (Lutian Reservoir and Lake Haitang) with different trophic status in China have been studied weekly from March to May in 2018, when the cyanobacteria communities were just in the early growth stage, to investigate the variation of MCs concentration and the relationships between MCs and environmental parameters. During the investigation, Lutian Reservoir and Lake Haitang were found to be mesotrophic and light eutrophic, respectively. In Lutian Reservoir, the concentration of EMCs (extracellular MCs) was obviously higher than that of IMCs (intracellular MCs) with a mean value of 0.323 and 0.264 μg/L, respectively. Meanwhile, the concentration of EMCs also fluctuated more sharply than that of IMCs. Congeners of IMC-YR and EMC-LR were respectively dominant in total concentrations of IMCs and EMCs. Unsurprisingly, in Lake Haitang, the concentrations of IMC and EMC were both significantly higher than that in Lutian Reservoir with a mean concentration of 0.482 and 0.472 μg/L, respectively. Differently, the concentration of MC-YR was dominant in both IMCs and EMCs, followed by MC-LR. In correlation analysis, the IMCs were significantly and positively correlated with the density and biomass of phytoplankton phyla and potential MCs-producing cyanobacteria and the parameters of water temperature (WT), nutrients, and organic matters. Similar results were also observed for EMCs. While the different variations of MCs in the two reservoirs might be primarily caused by the differences in WT, nutrients (especially phosphorus), organic matters, and the composition of MCs-producing cyanobacteria. In addition, the coexistence of the dominant species of Pseudoanabaena sp., which can produce a taste-and-odor compound of 2-methylisoborneol (2-MIB), might have a significant impact on the concentration and toxicity of MCs. Our results suggested that the risks posed by MCs at the early growth stage of cyanobacteria should also deserve our attention, especially in mesotrophic water bodies.
有害蓝藻水华的发生频率和严重程度正在增加，这使得其有毒次生代谢产物微囊藻毒素（MCs）受到了广泛研究，尤其是在不同生境中的分布及其影响因素方面。然而，MCs在有害蓝藻早期生长阶段的分布及其影响因素和风险仍 largely未知。因此，在本研究中，于2018年3月至5月每周对中国两个营养状态不同的水库（芦田水库和海棠湖）进行研究，此时蓝藻群落正处于早期生长阶段，以调查MCs浓度的变化以及MCs与环境参数之间的关系。在调查期间，发现芦田水库和海棠湖分别为中营养和轻度富营养。在芦田水库中，胞外MCs（EMCs）的浓度明显高于胞内MCs（IMCs），平均值分别为0.323和0.264μg/L。同时，EMCs浓度的波动也比IMCs更剧烈。IMC-YR和EMC-LR同系物分别在IMCs和EMCs的总浓度中占主导地位。不出所料，在海棠湖中，IMC和EMC的浓度均显著高于芦田水库，平均浓度分别为0.482和0.472μg/L。不同的是，MC-YR的浓度在IMCs和EMCs中均占主导地位，其次是MC-LR。在相关性分析中，IMCs与浮游植物门类和潜在产MCs蓝藻的密度和生物量以及水温（WT）、营养物质和有机物参数呈显著正相关。EMCs也观察到类似结果。而两个水库中MCs的不同变化可能主要是由WT、营养物质（尤其是磷）、有机物以及产MCs蓝藻的组成差异引起的。此外，能产生2-甲基异莰醇（2-MIB）这种嗅味化合物的伪鱼腥藻属优势种的共存，可能对MCs的浓度和毒性有显著影响。我们的结果表明，蓝藻早期生长阶段MCs带来的风险也应引起我们的关注，尤其是在中营养水体中。
