TY - JOUR
T1 - Quantum yields and N2O formation from photolysis of solid films of neonicotinoids
AU - Wang, Weihong
AU - Aregahegn, Kifle Z.
AU - Andersen, Simone T.
AU - Ni, Anton Z.
AU - Rohrbacher, Andrea F.
AU - Nielsen, Ole John
AU - Finlayson-Pitts, Barbara J.
PY - 2019
Y1 - 2019
N2 -
Neonicotinoids (NN), first introduced in 1991, are found on environmental surfaces where they undergo photolytic degradation. Photolysis studies of thin films of NN were performed using two approaches: (1) transmission FTIR, in which solid films of NN and the gas-phase products were analyzed simultaneously, and (2) attenuated-total-reflectance FTIR combined with transmission FTIR, in which solid films of NN and the gas-phase products were probed in the same experiment but not at the same time. Photolysis quantum yields using broadband irradiation centered at 313 nm were (2.2 ± 0.9) × 10
-3
for clothianidin (CLD), (3.9 ± 0.3) × 10
-3
for thiamethoxam (TMX), and (3.3 ± 0.5) × 10
-3
for dinotefuran (DNF), with all errors being ±1s. At 254 nm, which was used to gain insight into the wavelength dependence, quantum yields were in the range of (0.8-20) × 10
-3
for all NNs, including acetamiprid (ACM) and thiacloprid (TCD). Nitrous oxide (N
2
O), a potent greenhouse gas, was the only gas-phase product detected for the photolysis of nitroguanidines, with yields of N
2
O/NN > 0.5 in air at both 313 and 254 nm. The atmospheric lifetimes with respect to photolysis for CLD, TMX, and DNF, which absorb light in the actinic region, are estimated to be 15, 10, and 11 h, respectively, at a solar zenith angle of 35° and 12, 8, and 10 h at a solar zenith angle of 15°.
AB -
Neonicotinoids (NN), first introduced in 1991, are found on environmental surfaces where they undergo photolytic degradation. Photolysis studies of thin films of NN were performed using two approaches: (1) transmission FTIR, in which solid films of NN and the gas-phase products were analyzed simultaneously, and (2) attenuated-total-reflectance FTIR combined with transmission FTIR, in which solid films of NN and the gas-phase products were probed in the same experiment but not at the same time. Photolysis quantum yields using broadband irradiation centered at 313 nm were (2.2 ± 0.9) × 10
-3
for clothianidin (CLD), (3.9 ± 0.3) × 10
-3
for thiamethoxam (TMX), and (3.3 ± 0.5) × 10
-3
for dinotefuran (DNF), with all errors being ±1s. At 254 nm, which was used to gain insight into the wavelength dependence, quantum yields were in the range of (0.8-20) × 10
-3
for all NNs, including acetamiprid (ACM) and thiacloprid (TCD). Nitrous oxide (N
2
O), a potent greenhouse gas, was the only gas-phase product detected for the photolysis of nitroguanidines, with yields of N
2
O/NN > 0.5 in air at both 313 and 254 nm. The atmospheric lifetimes with respect to photolysis for CLD, TMX, and DNF, which absorb light in the actinic region, are estimated to be 15, 10, and 11 h, respectively, at a solar zenith angle of 35° and 12, 8, and 10 h at a solar zenith angle of 15°.
KW - acetamiprid
KW - clothianidin
KW - dinotefuran
KW - neonicotinoids
KW - thiacloprid
KW - thiamethoxam
U2 - 10.1021/acs.jafc.8b05417
DO - 10.1021/acs.jafc.8b05417
M3 - Journal article
C2 - 30698961
AN - SCOPUS:85061500814
SN - 0021-8561
VL - 67
SP - 1638
EP - 1646
JO - Journal of Agricultural and Food Chemistry
JF - Journal of Agricultural and Food Chemistry
IS - 6
ER -