Degradation Dynamics of Commercial Formulations of Postharvest Fungicides Fludioxonil and Pyrimethanil under Laboratory Conditions and in Degradation Pools in North Patagonia, Argentina

VEDELAGO, SOFÍA AYELEN; LATINI, LORENA; DI BLASI, LORENA; AGUIAR, BELEN; VILLANOVA, JORGELINA; ESPERT, NURIA GUADALUPE; VENTURINO, ANDRÉS; LASCANO, CECILIA INÉS

Montevideo

Congreso; SETAC Latin America 15th Biennial Meeting; 2023

SETAC

Commercial formulations of the postharvest fungicides fludioxonil (FLU) and pyrimethanil(PIR) are employed for conventional production of pears and apples in North Patagonia.During the productive season, a considerable volume of fungicide-contaminated water isgenerated, which is subjected to photolytic degradation in pools. However, their residencetime in the pools is uncertain, as well as the efficacy of the treatment. Objectives: todetermine if FLU and PIR are being degraded by photolysis in the sampled pools, and toestablish their degradation kinetics under laboratory conditions. Methods: Water sampleswere taken from the input and output of degradation pools belonging to two differentcompanies. FLU and PIR were identified and quantified in the samples after liquid-liquidextraction and injection into HPLC-UV. To evaluate the degradation kinetics under laboratoryconditions, the commercial formulations Scholar® 23SC (Syngenta; FLU 23% w/v) andPenbotec® 40 SC (Janssen Pharmaceutica; PIR 40% w/v) were used to prepare stocksolutions of known theoretical concentration, from which working solutions (10 mg/l) werethen prepared. Aeration was evaluated as a variable in the assays. The glass trayscontaining the solutions were covered with cling film and were kept in a room withtemperature control and photoperiod. The degradation kinetics was studied for 30 days.Samples were taken at different intervals, and were analyzed by HPLC-UV.Physico-chemical parameters were monitored. At the end of the analysis period, the traysthat contained FLU were rinsed with 10 ml of methanol and these samples were analyzed.Results: FLU was detected in all water samples collected from the degradation pools, whichcoincides with its usage during the productive season. PIR was also detected, even though itwas not actively being used. The concentrations measured in the output of degradationpools were superior to the concentrations of input. A decrease of FLU concentration wasobserved under laboratory conditions in the sampled water, but it was adsorbed to thesediment that settled on the bottom of the trays. PIR concentrations did not change.Conclusions: The photolytic degradation pools analyzed are not able to remove FLU andPIR from the effluents that are then discharged into the authorized receptors, that ultimatelyreach rivers or wastewater treatment plants. No degradation of PIR and FLU was observedunder laboratory conditions.