Seasonal Dynamics on Concentration of Fipronil Compounds through the Upstream of Water Source and Degradation during the Water Purification

Abstract

Seasonal dynamics of concentration of phenylpyrazole insecticide compounds, fipronil (FIP), fipronil sulfone (FIP+O) and fipronil sulfide (FIP-O) were surveyed through the upstream of the Sengari Reservoir for Kobe City. As a result, high concentration of FIP, FIP+O and FIP-O were detected immediately after rice planting. In the laboratory examination, FIP and FIP+O were promptly changed to fipronil sulfone chloramine ((FIP+O) Cl) after addition of sodium hypochlorite. On the other hand, the degradation of FIP-O were very low, and (FIP+O) Cl was not generated. Each of fipronil substance, FIP, FIP+O and FIP-O was effectively removed through activated carbon (powder activated carbon and granular activated carbon) treatment. However, removability of (FIP+O) Cl was low. Therefore, it is concluded that activated carbon treatment before the chlorine addition is effective to remove FIP compounds during water purification.