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

VL - 67

SP - 1638

EP - 1646

JO - Journal of Agricultural and Food Chemistry

JF - Journal of Agricultural and Food Chemistry

SN - 0021-8561

IS - 6

ER -