The impact of two insecticides on the pollutant cycle and quality of surface and groundwater resources in the irrigated lands of Yasuj, Iran

The increase in the need for food and agricultural development has led to an increase in the use of insecticides. The use of insecticides leads to air, soil and water pollution. This study investigated the pollutant concentration cycle in the environment by analyzing diazinon and deltamethrin in a river and groundwater sources affected by an agricultural area. The samples were analyzed based on the standard method for insecticides in water using a GC-MS. The results showed that the quality of the surface water affected by the agricultural effluents decreased so that the changes of dissolved oxygen, nitrate, turbidity, TOC, BOD, and COD were 15.2%, 189.6%, 00%, 53%, 176%, and 57.5%, respectively. The concentration of diazinon and deltamethrin in agricultural wastewater was 86 μg/L and 11.62 μg/L. The self-treatment capacity of the river reduced the concentration of diazinon in the distance of 2 km and 15 km by 80.8% and 90.3%, respectively. These conditions were observed for deltamethrin in 74.8% and 96.2%, respectively. Also, the concentration of the two insecticides in water resources has temporal and spatial variation. The difference between the maximum and minimum concentration of diazinon and deltamethrin at different times was 183.5 and 1.73, respectively. The concentration of diazinon and deltamethrin in the downstream groundwater of the studied irrigated area was 0.3–0.7 μg/L, respectively. Although the soil structure and the self-purification capacity of the river caused a significant reduction of insecticides, the remained concentration of these pollutants in underground and surface water resources can still be a health and environmental concern.