Transformation product and toxicity patterns of microcystin-LR (MC-LR), a common cyanotoxin in freshwaters, during degradation by solar photo-Fenton process were studied in the absence and presence of two major water components, namely fulvic acid and alkalinity. The transformation products m/z 795, 835, 515/1030 and 532 can be formed through attack of

OH on the conjugated carbon double bonds of Adda. Transformation products with m/z 1010, 966 and 513 can be generated through the attack of OH on the methoxy group of Adda. The transformation products m/z 783, 508 and 1012 can be originated from the attack of OH on the cyclic structure of MC-LR. Transformation products (m/z 522, 1028, 1012, 1046 and 514) formed after hydroxylation of the aromatic ring with OH were also identified in this study. The toxicity study revealed that fulvic acid and alkalinity strongly influence the toxicity profiles of solar photo-Fenton treated MC-LR. Fulvic acid enhanced the detoxification whereas low level total alkalinity (1.8 mg L^-1 CaCO₃) inhibited the detoxification of MC-LR by solar photo-Fenton process as assessed by protein phosphatase-1 (PP-1) inhibition assay. This work provides insights on the utility of solar photo-Fenton destruction of MC-LR in water based on transformation products and toxicity data.

中文翻译：

---

水环境中微囊藻毒素-LR 的太阳光芬顿处理：不同水基质中的转化产物和毒性

研究了微囊藻毒素-LR（MC-LR）（一种淡水中常见的蓝藻毒素）在太阳光芬顿过程降解过程中的转化产物和毒性模式，研究了两种主要水成分（即黄腐酸和碱度）存在和不存在的情况。通过攻击可形成m / z 795、835、515/1030 和 532 的转化产物

Adda 的共轭碳双键上有 OH。通过攻击可生成m / z 1010、966 和 513 的转化产物Adda 的甲氧基上有 OH。m / z 783、508 和 1012的转化产物可源自MC-LR 环状结构上的 OH。芳环羟基化后形成的转化产物（m / z 522、1028、1012、1046 和 514）本研究还鉴定了 OH。毒性研究表明，黄腐酸和碱度强烈影响经太阳光芬顿处理的 MC-LR 的毒性特征。黄腐酸增强了解毒作用，而低水平总碱度（1.8 mg L ^-1 CaCO ₃）通过太阳光芬顿过程抑制了 MC-LR 的解毒作用（通过蛋白磷酸酶-1（PP-1）抑制测定进行评估）。这项工作根据转化产物和毒性数据，提供了关于太阳光芬顿破坏水中 MC-LR 的效用的见解。