Purpose: Propanil is a contact herbicide used in post emergence to control barnyardgrass and several other weeds in rice. Several years ago all European registrations of propanil dropped after the introduction of a new regulatory legislation in the EU. Over the last two year, the product have been granted in Italy with an emergency authorization for a double application at 0.5 kg a.s. /ha in combination with other herbicides to control resistance in several rice weeds. At present, very little is known about the dissipation pattern of some important metabolites of propanil in water environment. The study aimed to evaluate the dissipation in surface water of propanil and its metabolites: 3,4-dichloroaniline (3,4 DCA), dichloronitrobenzene (DCNB), N-hydroxy-3,4- Dichloroazobenzene (DCAB), and 3,4',4,4'-tetrachloroazobenzene (TCAB). Approach and methods used: The study was carried out in 2012 and 2013 at Vercelli, north-west of Italy, in two paddy fields of about 2000 m2 each, cultivated according the two most adopted rice management systems diffuse in Europe: conventional water seeding with rice seeded in flooded field (CON) and dry seeding with rice seeded in dry field and flooding starting from rice tillering stage (DRY). Propanil was applied in post-emergence at a field rate of 0.5 kg ha-1. Water samples, collected both in the flooded fields and from the inlet and outlet floodgates, were taken at different intervals from herbicide application up to about 2 months after the treatment. The molecules were extracted by SPE, and analyzed by LC-MS/MS and HPLC. Key results: Propanil, 3,4 DCA and DCNB were the only compounds found in waters. Residues of propanil in paddy water were detected up to 48 hs and 72 hs after the treatment, in system CON and DRY respectively. 3,4 DCA and DCNB showed a longer persistence in paddy water. A month after the treatment, residues of 3,4 DCA were not higher than 0.12 µg/L, meanwhile the concentrations of DCNB ranged from 0.3 µg/L to 0.6 µg/L. Residues of 3,4 DCA and DCNB were occasionally detected in inlet waters. Propanil, 3,4 DCA and DCNB were found in outlet waters at high concentrations mostly in the period close to the herbicide treatment. Synthesis and Applications: 3,4DCA and DCNB showed a high risk of water contamination.
Dissipation of propanil and its main metabolites in paddy water
MILAN, MARCO;FERRERO, Aldo;DE PALO, FERNANDO;PIANO, Serenella;VIDOTTO, Francesco
2014-01-01
Abstract
Purpose: Propanil is a contact herbicide used in post emergence to control barnyardgrass and several other weeds in rice. Several years ago all European registrations of propanil dropped after the introduction of a new regulatory legislation in the EU. Over the last two year, the product have been granted in Italy with an emergency authorization for a double application at 0.5 kg a.s. /ha in combination with other herbicides to control resistance in several rice weeds. At present, very little is known about the dissipation pattern of some important metabolites of propanil in water environment. The study aimed to evaluate the dissipation in surface water of propanil and its metabolites: 3,4-dichloroaniline (3,4 DCA), dichloronitrobenzene (DCNB), N-hydroxy-3,4- Dichloroazobenzene (DCAB), and 3,4',4,4'-tetrachloroazobenzene (TCAB). Approach and methods used: The study was carried out in 2012 and 2013 at Vercelli, north-west of Italy, in two paddy fields of about 2000 m2 each, cultivated according the two most adopted rice management systems diffuse in Europe: conventional water seeding with rice seeded in flooded field (CON) and dry seeding with rice seeded in dry field and flooding starting from rice tillering stage (DRY). Propanil was applied in post-emergence at a field rate of 0.5 kg ha-1. Water samples, collected both in the flooded fields and from the inlet and outlet floodgates, were taken at different intervals from herbicide application up to about 2 months after the treatment. The molecules were extracted by SPE, and analyzed by LC-MS/MS and HPLC. Key results: Propanil, 3,4 DCA and DCNB were the only compounds found in waters. Residues of propanil in paddy water were detected up to 48 hs and 72 hs after the treatment, in system CON and DRY respectively. 3,4 DCA and DCNB showed a longer persistence in paddy water. A month after the treatment, residues of 3,4 DCA were not higher than 0.12 µg/L, meanwhile the concentrations of DCNB ranged from 0.3 µg/L to 0.6 µg/L. Residues of 3,4 DCA and DCNB were occasionally detected in inlet waters. Propanil, 3,4 DCA and DCNB were found in outlet waters at high concentrations mostly in the period close to the herbicide treatment. Synthesis and Applications: 3,4DCA and DCNB showed a high risk of water contamination.
I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
