Abstract：
Harmful cyanobacterial blooms will be more intense and frequent in the future, contaminating surface waters with cyanotoxins and posing a threat to communities heavily reliant on surface water usage for crop irrigation. Constructed wetlands (CWs) are proposed to ensure safe crop irrigation, but more research is needed before implementation. The present study operated 28 mesocosms in continuous mode mimicking horizontal sub-surface flow CWs. Mesocosms were fed with synthetic lake water and spiked periodically with two cyanotoxins, microcystin-LR (MC-LR) and cylindrospermopsin (CYN), at environmentally relevant cyanotoxins concentrations (10 μg L-1). The influence of various design factors, including plant species, porous media, and seasonality, was explored. The mesocosms achieved maximum MC-LR and CYN mass removal rates of 95 % and 98 %, respectively. CYN removal is reported for the first time in CWs mimicking horizontal sub-surface flow CWs. Planted mesocosms consistently outperformed unplanted mesocosms, with Phragmites australis exhibiting superior cyanotoxin mass removal compared to Juncus effusus. Considering evapotranspiration, J. effusus yielded the least cyanotoxin-concentrated effluent due to the lower water losses in comparison with P. australis. Using the P-kC* model, different scaling-up scenarios for future piloting were calculated and discussed. Additionally, bacterial community structure was analyzed through correlation matrices and differential taxa analyses, offering valuable insights into their removal of cyanotoxins. Nevertheless, attempts to validate microcystin-LR biotransformation via the known mlrA gene degradation pathway were unfruitful, indicating alternative enzymatic degradation pathways occurring in such complex CW systems. Further investigation into the precise molecular mechanisms of removal and the identification of transformation products is needed for the comprehensive understanding of cyanotoxin mitigation in CW. This study points towards the feasibility of horizontal sub-surface flow CWs to be employed to control cyanotoxins in irrigation or recreational waters.
摘要：
今后有害的蓝藻水华将更加强烈和频繁,用氰基毒素污染地表水，并对严重依赖地表水用于作物灌溉的社区构成威胁。建议使用人工湿地（CWs）以确保安全的农作物灌溉，但是在实施之前需要更多的研究。本研究以模拟水平亚表面流CW的连续模式运行了28个中观。Mesocoss用合成湖水喂养，并定期添加两种氰基毒素，微囊藻毒素-LR（MC-LR）和圆柱精氨素（CYN），在环境相关的氰基毒素浓度（10μgL-1）。各种设计因素的影响，包括植物物种,多孔介质,和季节性，被探索了。mesocoss实现了最大MC-LR和CYN质量去除率95%和98%，分别。首次报道了模拟水平地下流CW的CW中的CYN去除。种植的中观总是优于未种植的中观，与Juncuseffusus相比，芦苇表现出优异的蓝藻毒素质量去除效果。考虑到蒸散,J.Effusus产生的蓝藻毒素浓缩废水最少，因为与澳大利亚假单胞菌相比，水损失较低。使用P-kC*模型，计算并讨论了未来试点的不同放大方案。此外,通过相关矩阵和分类群分析分析细菌群落结构，提供了有价值的见解，以去除他们的氰基毒素。然而，通过已知的mlrA基因降解途径验证微囊藻毒素-LR生物转化的尝试是无效的，表明在这种复杂的CW系统中发生的替代酶促降解途径。为了全面了解CW中氰基毒素的缓解，需要进一步研究去除的精确分子机制和转化产物的鉴定。这项研究指出了水平地下流CW用于控制灌溉或娱乐水域中氰基毒素的可行性。
