TY - JOUR

T1 - OH radical reactivity of pesticides adsorbed on aerosol materials

T2 - First results of experiments with filter samples

AU - Palm, Wolf Ulrich

AU - Millet, Maurice

AU - Zetzsch, Cornelius

N1 - Copyright 1998 Academic Press.

PY - 1998/9/1

Y1 - 1998/9/1

N2 - Preliminary results of a new method to investigate the OH radical reactivity of semi-volatile organic compounds (e.g., pesticides) are presented. Terbuthylazine, simazine, sodium benzoate, and bromoxynil were adsorbed on highly disperse silicon dioxide powder as an unreactive carrier at a thickness well below one monolayer. The coated material was suspended in air as an aerosol, sampled on filters, and exposed in an 840-liter Duran chamber to OH radicals, produced by photolysis of hydrogen peroxide in the gas phase. Sunlamps on top of the chamber were used as cold light sources [T(aerosol) ≃ 25°C]. OH radical concentrations (105< c(OH) (cm-3) < 3 x 106) were monitored in the gas phase using a set of four hydrocarbons with well-known OH reactivities as reference compounds. The triazine terbuthylazine (k(OH)=1.1 x 10-11 cm3 s-1) was used as a reference compound in the filter samples. Simazine and isoproturon were found to react with a comparable OH rate constant with respect to terbuthylazine. Sodium benzoate reacts about a factor of 3 slower. Rapid degradation was observed for bromoxynil, explained mainly by photolysis. Besides the characterization and discussion of the experimental setup used, the rate constants obtained are discussed and compared with estimated values.

AB - Preliminary results of a new method to investigate the OH radical reactivity of semi-volatile organic compounds (e.g., pesticides) are presented. Terbuthylazine, simazine, sodium benzoate, and bromoxynil were adsorbed on highly disperse silicon dioxide powder as an unreactive carrier at a thickness well below one monolayer. The coated material was suspended in air as an aerosol, sampled on filters, and exposed in an 840-liter Duran chamber to OH radicals, produced by photolysis of hydrogen peroxide in the gas phase. Sunlamps on top of the chamber were used as cold light sources [T(aerosol) ≃ 25°C]. OH radical concentrations (105< c(OH) (cm-3) < 3 x 106) were monitored in the gas phase using a set of four hydrocarbons with well-known OH reactivities as reference compounds. The triazine terbuthylazine (k(OH)=1.1 x 10-11 cm3 s-1) was used as a reference compound in the filter samples. Simazine and isoproturon were found to react with a comparable OH rate constant with respect to terbuthylazine. Sodium benzoate reacts about a factor of 3 slower. Rapid degradation was observed for bromoxynil, explained mainly by photolysis. Besides the characterization and discussion of the experimental setup used, the rate constants obtained are discussed and compared with estimated values.

KW - Aerosol

KW - Bromoxynil

KW - Filter samples

KW - Isoproturon

KW - OH concentration

KW - OH rate constants

KW - Pesticides

KW - Simazine

KW - Sodium benzoate

KW - Terbuthylazine

KW - Chemistry

UR - http://www.scopus.com/inward/record.url?scp=0031696742&partnerID=8YFLogxK

U2 - 10.1006/eesa.1998.1664

DO - 10.1006/eesa.1998.1664

M3 - Journal articles

C2 - 9756687

AN - SCOPUS:0031696742

VL - 41

SP - 36

EP - 43

JO - Ecotoxicology and Environmental Safety

JF - Ecotoxicology and Environmental Safety

SN - 0147-6513

IS - 1

ER -