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Profenofos is a detectable insecticide in the environment with strong toxicity to non-targeted organisms. Photodegradation is a main transformation of profenofos in the environment. Myricetin is a flavonoid that strongly scavenges free radicals. The effect of myricetin on the photodegradation of profenofos was studied. The half-lives (T1/2) of profenofos were 1.7–7.0 and 90 h under artificial light and sunlight. The photolysis rate of profenofos decreased by 1.87–4.72 and 7.62 times with the addition of 20 ratios of myricetin. Free radicals reacting with profenofos were •OH and 1O2, and the key free radical was •OH. Myricetin strongly scavenged •OH and 1O2 which rapidly reacted with profenofos. O-(2-Chlorophenyl)-O-ethyl-S-propyl phosphorothioate (M3) and O-(2-chlorophenyl)-O-ethyl phosphorothioate (M4) were major and new photoproducts of profenofos. According to the Ecological Structure Activity Relationships, photodegradation of profenofos was a detoxification process, but myricetin inhibited the photodegradation of profenofos and its photoproducts. These results highlight the implication of myricetin on the fate and potential risk of profenofos in the environment. [ABSTRACT FROM AUTHOR]

BACKGROUND Chlorothalonil is a conventional chloroaromatic fungicide and is toxic to many aquatic species. This study was designed to investigate the effects of six flavonoids on the photolysis of chlorothalonil under sunlight and artificial light. RESULTS: Flavonoids sensitized the photolysis of chlorothalonil under sunlight and artificial light by 6.7–18.3 and 2.4–7.5 times, respectively, in comparison with a flavonoid‐free control. Photosensitization effect of each of the six flavonoids was greater under sunlight irradiation than under high‐pressure mercury lamp irradiation. Cyanidin showed greater photosensitization effects than luteolin, galangin, quercetin, morin and kaempferol. Chlorothalonil underwent photo‐reductive dechlorination and no hydrolysis product was formed in the presence of flavonoids. Hydroxyl and hydrogen radicals were detected in the absence and presence of cyanidin, respectively, under light irradiation. CONCLUSION: The photosensitization effect of flavonoids on chlorothalonil photolysis is apparently related to flavonoid structure and might be due to their hydrogen donation capacity. These results highlight benefit of using flavonoids to manage aquatic pollution and reduce aquatic toxicity, and have great relevance in predicting the degradation kinetics and biological impacts of chlorothalonil in surface water. © 2020 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Chlorothalonil is an important broad-spectrum fungicide with an annual application rate of above ten thousands of tons of its active ingredient on agricultural crops world-wide. The effect of procyanidolic oligomers on photo degradation of chlorothalonil was investigated under sunlight and artificial lights. Procyanidolic oligomers enhanced photodegradation of chlorothalonil in paddy, reservoir, pond and distilled waters for 1.8, 4.6, 2.7 and 22.8 fold, respectively, relative to the procyanidolic oligomers free control. The mechanism was evidenced as a radical reduction reaction by electron paramagnetic resonance spectroscopy. Upon exposure to high-pressure mercury light, chlorothalonil produced 2,4,5-trichloro-1,3-dicyanobenzene, 2,5-dichloro-1,3-dicyanobenzene and 5-chloro-1,3-dicyanobenzene that were isolated, identified and characterized. Chlorothalonil underwent primarily step-wide photo reductive dechlorination in the presence of procyanidolic oligomers, which avoided the production of the highly toxic 4-hydroxy chlorothalonil. Procyanidolic oligomers possessed strong reductive property to photo reductive dechlorination. The results contributed to understanding of chlorothalonil phototransformation and high potential of using natural product procyanidolic oligomers as an additive to minimize aquatic toxicity and pollution of chlorothalonil. [ABSTRACT FROM AUTHOR]

Flavonoids can sensitize and quench the photolysis of pesticides such as profenofos in surface water. Profenofos has been frequently detected in surface and underground water. The present study investigated the photolysis of profenofos under various conditions, including natural and artificial light illumination, with and without cyanidin-3- O -glucoside (Cy3G) and in pure and surface water. The degradation half-lives of profenofos in distilled water with 10 equivalents Cy3G of profenofos were 21.7 min, 9.5 h, 12.5 h and 180 h under high-pressure mercury light, UV, Xenon lamp and solar irradiation, respectively, while those without Cy3G were 8.1 min, 6.1 h, 8.2 h and 89.9 h, respectively. The photolysis rate of profenofos under sunlight and artificial light was reduced by 1.5–2.7 times due to Cy3G, compared to the Cy3G-free control. Under sunlight irradiation, the effects of Cy3G on profenofos photolysis were larger than those under high-pressure mercury lamp irradiation. Cy3G also significantly reduced the photolysis rate of profenofos under different pH conditions and in natural water. In addition, Cy3G exhibited a significant capacity of scavenging hydroxyl radicals and quenching 1O 2 in water. The effect of Cy3G on profenofos photolysis was demonstrated through their interrelations in the natural environment. These findings can help understanding of the effect of flavonoids on profenofos photolysis and are of significance for predicting the degradation kinetics of profenofos and accurately assessing its potential biological impacts. [Display omitted] • Cyanidin-3- O -glucoside (Cy3G) decreased photolysis rate of profenofos. • Profenofos preferred photodegradation in high pH value with/or without Cy3G. • The photolysis rates of profenofos were lower in natural water than in distilled water. • Cy3G exhibited the capacity of scavenging hydroxyl radicals and 1O 2 in water. [ABSTRACT FROM AUTHOR]

Triketone herbicides can be transformed to high toxic xanthenediones in water. In this work, bismuth oxychloride (BiOCl) was synthesized and used for degradation of tembotrione (TEM), a triketone herbicide. BiOCl increased the photolytic efficiencies of TEM in distilled water 12.3–36.9 times under different light irradiation and 0.68 and 0.43 times in tap water and pond water under high pressure mercury light (HPML), respectively. Attributed to the strong absorption induced by the BiOCl catalyst, HPML exhibited the highest TEM transformation kinetics. Fulvic acid in water significantly reduced the transformation. Reactive species 1O 2 , O 2 •− and h+ formed in the BiOCl catalysis system were confirmed to play an important role in TEM degradation. TEM underwent Baeyer-Villiger oxidation and avoided the formation of highly toxic intermediates. The findings helps in understanding of TEM transformation and utilization of BiOCl to effectively reduce aquatic toxicity and pollution of TEM. • Bismuth oxychloride (BiOCl) catalyzes photolysis of tembotrione. • h +, 1O 2 , and O 2 •− attribute to the photocatalysis. • BiOCl altered the photolysis pathway of tembotrione. • Photolysis of tembotrione catalyzed by BiOCl led no toxic xanthenedione generation. [ABSTRACT FROM AUTHOR]