Dissipation of Carpropamid from Water: Effect of pH, Temperature and Concentration

The wide spread concern over the adverse effect of pesticides on aquatic environment makes it pertinent to study the dissipation of pesticides in water. Dissipation of carpropamid (a fungicide for control of rice blast) was studied in water under different pH, temperature and concentrations. Residues of carpropamid in water were extracted by partitioning with dichloromethane. In all the treatments the residues of carpropamid persisted beyond 120 days. The dissipation rate was found to be the fastest at pH 4 (t_½ 334.4 days) followed by pH 9.2 (t_½ 430 days) and pH 7 (t_½ 376.3 days) and the rate was slightly faster at 40°C (t_½ 334.4 days) as compared to 4 and 25°C (t_½ 376.4 days). The faster dissipation of the compound at higher temperature and acidic/basic pH could be due to the hydrolysis of the amide linkage in the molecule. It was also found that there is no effect of fortification level on the dissipation of carpropamid in water.