title: Effect of phenolic mediators and humic acid on cyprodinil transformation in presence of birnessite.
abstract: Naturally occurring phenols were evaluated as mediators for the transformation of the fungicide cyprodinil by birnessite. With birnessite alone, cyprodinil transformation was negligible (0.6%). In the presence of mediators, however, it increased considerably (1.5-60.9%). With some exceptions (2,6-dimethoxyphenol, syringic acid), methoxylated phenols showed a substantial capacity for enhancing the transformation. Mass spectrometry indicated that cyprodinil cross-coupled with free radicals of phenols formed at birnessite surfaces. The extent of cyprodinil transformation in the presence of syringaldehyde, m-methoxyphenol, or vanillin increased with the amount of birnessite. In reactions with o- and p-methoxyphenol and vanillic acid, cyprodinil transformation was unaffected by the amount of birnessite, but it increased with increasing phenol concentration. The addition of various humic acids at low concentrations (5-10 mg/L) had little effect on cyprodinil transformation in the presence of o-methoxyphenol or syringaldehyde. At higher concentrations, however, humic acids inhibited the transformation (by 5-20%) when o-methoxyphenol was a mediator, but showed no effect in the presence of syringaldehyde.
authors.affiliation: Environmental R&D Team, Technology Research Institute, Daelim Industrial Co., Ltd., 146-12 Susong-dong Jongno-gu, Seoul 110732, South Korea.
authors.forename: Ki-Hoon
authors.initials: KH
authors.lastname: Kang
authors.forename: Jerzy
authors.initials: J
authors.lastname: Dec
authors.forename: Heekyung
authors.initials: H
authors.lastname: Park
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Bollag
mesh_terms: D001711:Biotransformation; D006812:Humic Substances; D008277:Magnesium Oxide / Q000737:chemistry*; D013058:Mass Spectrometry; D010084:Oxidation-Reduction; D011743:Pyrimidines / Q000378:metabolism*; D013696:Temperature; D014867:Water / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000378:metabolism*
chemical_list: D006812:Humic Substances; D011743:Pyrimidines; D014874:Water Pollutants, Chemical; D014867:Water; D008277:Magnesium Oxide; C108338:cyprodinil