Improving the Estimation Accuracy of the AIST-SHANEL Model by Traction Coefficient Calibration of Multiple Surfactants

Abstract

General and precise environmental exposure models are required for exposure evaluations in environmental risk assessments of chemical substances. In this study, to understand the practical use of exposure models, the performance of the model AIST-SHANEL ver. 3.0 was evaluated by estimating the concentrations of five surfactants with different physicochemical properties [linear alkylbenzene sulfonate (LAS) , amine oxide (AO) , alcohol ethoxylate (AE) , ester-amide-type dialkyl amine salt (EA) , and triethanolamine quaternary salt (TEAQ) ] in rivers. Furthermore, the relationship between the organic carbon-water partition coefficient (K_oc) , which is related to adsorption onto soil particles, and the traction coefficient in mathematical models, which represents parameters of wet-weather effluent load in the sediment, was investigated. Good estimation performances were confirmed using a traction coefficient of 30 m^-1 for chemical substances with relatively small K_oc values (LAS, AE, and AO; in the order of 1×10³ L kg^-1) , and traction coefficients of 300-1000 m^-1 for chemical substances with high K_oc values (EA and TEAQ; in the order of 1×10^5-6 L kg^-1) . By selecting the appropriate traction coefficient on the basis of the K_oc value of chemical substances, the AIST-SHANEL model can be used as an exposure analysis tool to precisely estimate concentrations of various chemical substances.