benzovindiflupyr (ISO); N-[9-(dichloromethylene)-1,2,3,4-tetrahydro-1,4-methanonaphthalen-5-yl]-3-(difluoromethyl)-1-methyl-1H-pyrazole-4-carboxamide

Phototransformation in water

Description of key information

photo-degradation in aqueous solution: rapid in natural water (DegT50: 5.0 days, indirect photolysis) but slower in buffer solution (DegT50; 44.2 days, direct photolysis)

Additional information

DegT50 and DegT90 values for SYN545192 under irradiated conditions

Test System	Direct photolysis [0.01M pH 7 phosphate buffer]					Direct and Indirect photolysis [natural water]
	DegT50[days]	DegT90[days]	χ^2%	r^2	Prob>t	DegT50[days]	DegT90[days]	χ^2%	r^2	Prob>t
Irradiated (experimental result)	44.2	146.7	3.6	0.6	1.1e^-7	5.0	16.7	10.1	0.9	1.6e^-12
Dark control (experimental result)	Stable					Stable
Corrected DegT50for different latitudes
Summer Sunlight 30-50ºN (OECD)	95.2	316.1	3.6	0.6	1.2e^-7	10.4	34.6	10.0	0.9	1.5e^-12
Tokyo Spring Sunlight (JMAFF)	307.1	>1000	3.6	0.6	1.1e^-7	33.7	112.0	10.1	0.9	1.6e^-12

 

Photo-degradation of SYN545192 in aqueous solution was rapid in natural water but slower under direct photolysis, indicating that indirect photolysis is likely to be a significant degradation mechanism for the compound in surface waters. Experimental half-lives (DegT50) of 44.2 days (phenyl and pyrazole combined) and 5.0 days (phenyl and pyrazole combined) were determined in buffer and natural water, respectively. The equivalent degradation rates in days summer sunlight at 30-50°N were 95.2 days for direct photolysis and 10.4 days for natural water photolysis. Degradation in the dark control samples was not observed.

Direct photolysis of SYN545192 resulted in cleavage between the ring systems and ultimately in mineralization. Two degradates, NOA449410 and SYN508272, which were specific to the pyrazole label, reached maximum levels of 8.5% and 2.6% AR respectively. No phenyl specific degradates were identified. A number of other minor components were observed in both labels but none exceeded levels of >5% of the applied dose. Levels of 14CO2 increased over the course of the experiment, reaching maximum mean values of 6.3% AR and 1.1% AR in the phenyl and pyrazole labelled samples respectively by the end of the irradiation period.

The photolytic degradation pattern for SYN545192 was similar in irradiated natural water samples. The pyrazole specific degradates NOA449410 and SYN508272, were formed and reached maximum levels of 36.4% and 23.5% AR respectively by 15 DAT. A number of minor components were observed, none of which exceeded levels of >5% of the applied dose. 14CO2 reached maximum mean levels of 25.1% AR and 11.1% AR in the 15 DAT phenyl and pyrazole samples respectively.