Determination of residual concentrations of organophosphorus pesticides in surface and groundwater sources supplying drinking water of Tehran city

Pollution of water resources by increased use of pesticides is one of the environmental problems. The aim of present research is the determination of residual Diazinon and Chlorpyrifos in surface and groundwater resources of Tehran city (2018). 12 samples were taken from 6 water source stations in 3 geographical regions on Tehran city. we designed new experiments to evaluate the rate of decomposition of pesticides in water, consider the two states of stagnant and current water, each sample was impregnated with 3 Liters of water with 50 mg/L, the active ingredient of the formulation of each of the pesticides studied, then the extraction method was performed at intervals of 0, 5, 10, 15, 20 and 25 days. The liquid-liquid extraction method was used and residual pesticides measurement was accomplished by GC/ NPD. In the stagnant water samples of all the stations, the results of the mean concentration of 3 replicates show a decreasing trend of the residual concentration of the pesticides in over time, but in the 25th day of extraction, the residual amount of pesticides did not reach zero, but in the current water samples, the results showed that the residual concentration of the pesticides was not measurable from the 15th to the 25th day of extraction. The simulation of the current state of the water using the aquarium pump is likely to increased oxidation of pesticides has increased their rate of degradation.