Degradation dynamics of commercial formulations of postharvest fungicides fludioxonil and pyrimethanil under laboratory conditions and in degradation pools in North Patagonia, Argentina

VEDELAGO S; LATINI L; DIBLASI L; AGUIAR B; VILLANOVA JL; ESPERT NURIA; VENTURINO A; LASCANO C; LUTZ MC

Montevideo

Congreso; SETAC Latin America 15th Biennial Meeting; 2023

SETAC LA

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 is generated, which is subjected to photolytic degradation in pools. However, their residence time in the pools is uncertain, as well as the efficacy of the treatment. Objectives: to determine if FLU and PIR are being degraded by photolysis in the sampled pools, and to establish their degradation kinetics under laboratory conditions. Methods: Water samples were taken from the input and output of degradation pools belonging to two different companies. FLU and PIR were identified and quantified in the samples after liquid-liquid extraction and injection into HPLC-UV. To evaluate the degradation kinetics under laboratory conditions, the commercial formulations Scholar® 23SC (Syngenta; FLU 23% w/v) and Penbotec® 40 SC (Janssen Pharmaceutica; PIR 40% w/v) were used to prepare stock solutions of known theoretical concentration, from which working solutions (10 mg/l) were then prepared. Aeration was evaluated as a variable in the assays. The glass trays containing the solutions were covered with cling film and were kept in a room with temperature 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 trays that 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, which coincides with its usage during the productive season. PIR was also detected, even though it was not actively being used. The concentrations measured in the output of degradation pools were superior to the concentrations of input. A decrease of FLU concentration was observed under laboratory conditions in the sampled water, but it was adsorbed to the sediment 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 and PIR from the effluents that are then discharged into the authorized receptors, that ultimately reach rivers or wastewater treatment plants. No degradation of PIR and FLU was observed under laboratory conditions.