Many ultraviolet (UV) experiments are conducted without ensuring that fluence is measured accurately, which may significantly affect the interpretation of the findings. This is especially evident for microcystin-LR, a common cyanobacterial toxin. Reports on the effectiveness of direct photolysis of microcystin-LR by 254 nm UV light are highly inconsistent in the literature, with pseudo-first-order rate coefficients reported from 10^–2 to 10^–5 cm²/mJ. It is demonstrated systematically that most of these studies did not follow proper fluence calculation procedures. The findings of improper studies were eliminated or, if possible, corrected using standard protocols. After accounting for these deficiencies, we find the average rate coefficient is 3.1 ± 0.82 × 10^–3 cm²/mJ and is used to determine a new quantum yield at 254 nm (0.048 mol/Einstein). These findings are used to recharacterize the photolysis of microcystin-LR whereby it is shown that in ultrapure water 84% of the microcystin-LR can be transformed into nontoxic products by a fluence of 600 mJ/cm², typical of UV advanced oxidation. Thus, direct photolysis may be an important part of a multibarrier treatment approach.

中文翻译：

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准确测量紫外线通量的重要性：直接光解法去除微囊藻毒素-LR的综述

在进行许多紫外线（UV）实验时，并未确保准确测量通量，这可能会严重影响结果的解释。对于微囊藻毒素-LR（一种常见的蓝细菌毒素）而言，这一点尤其明显。关于用254 nm紫外线直接对微囊藻毒素-LR进行光解的有效性的报道在文献中高度不一致，报道的伪一级速率系数为10 ^–2至10 ^–5 cm ² / mJ。系统地证明，这些研究大多数没有遵循适当的注量计算程序。不当研究的发现被消除，或者，如果可能的话，使用标准方案予以纠正。弥补这些不足后，我们发现平均比率系数为3.1±0.82×10^–3 cm ² / mJ，用于确定254 nm（0.048 mol / Einstein）处的新量子产率。这些发现被用于表征微囊藻毒素-LR的光解，从而表明在超纯水中，通过600 mJ / cm ²的通量（典型的紫外线高级氧化反应），微囊藻毒素-LR可以将84％的微囊藻毒素-LR转化为无毒产品。因此，直接光解可能是多屏障处理方法的重要组成部分。