1. Academic Validation
  2. Effects of fertilization on the triafamone photodegradation in aqueous solution: Kinetic, identification of photoproducts and degradation pathway

Effects of fertilization on the triafamone photodegradation in aqueous solution: Kinetic, identification of photoproducts and degradation pathway

  • Ecotoxicol Environ Saf. 2020 May:194:110363. doi: 10.1016/j.ecoenv.2020.110363.
Guofeng Chen 1 Yuxin Qiao 2 Feng Liu 3 Xiaobo Zhang 3 Hui Liao 3 Ruiying Zhang 3 Jiannan Dong 3
Affiliations

Affiliations

  • 1 Safety and Quality Institute of Agricultural Products, Heilongjiang Academy of Agricultural Sciences, Harbin, 150086, China. Electronic address: hljjiance@163.com.
  • 2 Jiangsu Key Laboratory of Pesticide Science, College of Sciences, Nanjing Agricultural University, Nanjing, 210095, China.
  • 3 Safety and Quality Institute of Agricultural Products, Heilongjiang Academy of Agricultural Sciences, Harbin, 150086, China.
Abstract

Triafamone is a highly effective, low toxicity sulfonamide herbicide widely used for weeding paddy fields. The triafamone photodegradation in water environment must be explored for its ecological risk assessment. In this work, the effects of chemical fertilizer (urea, diammonium phosphate, potassium chloride, and potassium sulfate), urea metabolites (CO32- and HCO3-), and organic fertilizers (unfermented organic fertilizer [UOF] and fermented organic fertilizer [FOF]) on the triafamone photodegradation in aqueous solution under simulated sunlight were evaluated. Results showed that the triafamone photodegradation rate was unaffected by urea. The half-life of triafamone decreased from 106.8 h to 68.4 h with increasing diammonium phosphate concentration. Potassium chloride, potassium sulfate, CO32-, and HCO3- could accelerate the triafamone photodegradation at all concentrations, whereas the degradation rate of triafamone decreased when the concentration of potassium sulfate or CO32- was 2000 mg/L. Triafamone photodegradation was promoted by 20-200 mg/L UOF and FOF but decreased to 236.6 and 142.3 h when the concentration reached 2000 mg/L. Twenty-three transformation products were isolated and identified from triafamone by using ultra-performance liquid chromatography with quadrupole time-of-flight mass spectrometry under simulated sunlight irradiation, and the kinetic evolution of these products was explored. Five possible degradation pathways were inferred, including the cleavage of C-N, C-C, and C-O bonds; CO bond hydrogenation; the cleavage of triazine ring; the cleavage of the sulfonamide bridge; hydroxylation; hydroxyl substitution; methylation; demethylation; amination; and rearrangement. In summary, these results are important for elucidating the environmental fate of triafamone in aquatic systems and further assessing environmental risks.

Keywords

Degradation pathway; Fertilizer; Photodegradation; Transformation product; Triafamone.

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