RISK ASSESSMENT FOR SOIL SPREADING OF CLOTHIANIDIN AS TERMITICIDE—ESTIMATION OF ADSORPTION BEHAVIOR ON SOIL PARTICLES OF SPREADING AGENTS BASED ON MULTI-PHASE AND MULTI-COMPONENT FLOW MODEL UNDER THE ENVIRONMENT OF SOIL AND GROUNDWATER—

Abstract

 In this study, on the basis of transport phenomena of chemical substances in soil and groundwater and estimation of exposure on human body, we aim at risk assessment for soil spreading of clothianidin as termiticide.
 We firstly described a numerical analysis model for multi-phase and multi-component systems considering a series of physical phenomena with soil spreading of termiticide. Then, for the purpose of estimation of adsorption behavior on soil particles, batch and column tests targeting multi-component systems consisting of IPBC, IAA and CIAA as model substances for antiseptic and fungicide in addition to clothianidin were conducted. As a result, it was found that the sorbability of each agent component on soil grain surface ranged from 1/10 to 1 compared with the results from batch tests due to the difference of the contact condition between dissolved components and soil grain in the micro pore space. Furthermore, using the numerical model, we optimized adsorption parameters for each agent through history matching for breakthrough curves obtained from a series of column tests.