Photo-transformation of isoproturon under UV-A irradiation: The synergy of nitrite and natural organic matter.

Autor: Wang H; Department of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China., Wang S; Department of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China., Jia Z; Department of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China., Li H; Department of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China., Wang J; Department of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China., Zhang T; Department of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China., Dong J; Department of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China., Yang P; Department of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China. Electronic address: peizeng@njau.edu.cn., Chen J; Department of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China., Ji Y; Department of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China., Lu J; Department of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China.
Jazyk: angličtina
Zdroj: Environmental pollution (Barking, Essex : 1987) [Environ Pollut] 2024 Jul 15; Vol. 353, pp. 124153. Date of Electronic Publication: 2024 May 13.
DOI: 10.1016/j.envpol.2024.124153
Abstrakt: Isoproturon (IPU), a widely utilized phenylurea herbicide, is recognized as an emerging contaminant. Previous studies have predominantly attributed the degradation of IPU in natural waters to indirect photolysis by natural organic matter (NOM). Here, we demonstrate that nitrite (NO 2 - ) also serves as an important photosensitizer that induces the photo-degradation of IPU. Through radical quenching tests, we identify hydroxyl radicals (•OH) and nitrogen dioxide radicals (NO 2 • ) originating from NO 2 - photolysis as key players in IPU degradation, resulting in the generation of a series of hydroxylated and nitrated byproducts. Moreover, we demonstrate a synergistic effect on the photo-transformation of IPU when both NOM and NO 2 - are present in the reaction mixture. The observed rate constant (k obs ) for IPU removal increases to 0.0179 ± 0.0002 min -1 in the co-presence of NO 2 - (50 μM) and NOM (2.5 mg C /L), surpassing the sum of those in the presence of each alone (0.0135 ± 0.0004 min -1 ). NOM exhibits multifaceted roles in the indirect photolysis of IPU. It can be excited by UV and transformed to excited triplet states ( 3 NOM*) which oxidize IPU to IPU •+ that undergoes further degradation. Simultaneously, NOM can mitigate the reaction by reducing the IPU •+ intermediate back to the parent IPU. However, the presence of NO 2 - alters this dynamic, as IPU •+ rapidly couples with NO 2 • , accelerating IPU degradation and augmenting the formation of mono-nitrated IPU. These findings provide in-depth understandings on the photochemical transformation of environmental contaminants, especially phenylurea herbicides, in natural waters where NOM and NO 2 - coexist.
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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Databáze: MEDLINE
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