Effect of phenolic mediators and humic acid on cyprodinil transformation in presence of birnessite.
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.
Kang
Ki-Hoon
KH
Environmental R&D Team, Technology Research Institute, Daelim Industrial Co., Ltd., 146-12 Susong-dong Jongno-gu, Seoul 110732, South Korea.
Dec
Jerzy
J
Park
Heekyung
H
Bollag
Jean-Marc
JM
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*
D006812:Humic Substances; D011743:Pyrimidines; D014874:Water Pollutants, Chemical; D014867:Water; D008277:Magnesium Oxide; C108338:cyprodinil