An ecological assessment of toluene in accidental spill scenario using AQUATOX model in rivers

Abstract

Huge chemical spill on environmental water system affect not only water quality but also ecological systems. However, site-specific monitoring of damage of chemical spill on ecological system costs lots of money and labor power. As a reason for that, modeling assessment of fate and interaction of the chemical accident is important. AQUATOX is a powerful ecological model with sufficient verification of literature studies. This Model considers parameters including water quality, toxic materials, and aquatic organisms. Some studies using AQUATOX already have calculated the site-specific impact of chemicals. This study strengthened the hydrodynamics of water flow by using the EFDC model and apply the new methodology to calculate chemical spill accident case. Toluene was selected by considering both possibilities of accident and hazard. And Jeonju River was targeted by taking into account total dealings of the chemicals at the instant industrial area and ecological value of the site. The hydraulic dynamics was modeled by EFDC and the ecological interaction was modeled by AQUATOX. To consider hydrodynamics, using the output data of the EFDC model which are flow rate and mean depth as input data into each segment of AQUATOX model. Ecotoxicity of toluene in the accidental situation at Jeonju River was calculated by biomass change of organisms by AQUATOX model. Chemical accident scenarios of spilling 3,000kg of toluene during a day and 30,000kg of toluene during a day or two days are simulated. The area between Sam-cheon2 and 2.5km from Sam-Cheon 2 point is the target site and the area is divided into 5 segments to consider the spatial variation of chemical concentration. From assessing toluene in the median state of Jeonju River, the biomass of species in Jeonju River decreased negligibly, each of them loses maximum 0.015% and 0.4% of the biomass of most vulnerable species. And also result of AQUATOX simulation shows toluene is eliminated too easily from the natural water system to affect ecology. Results of ecological modeling of the aquatic system show toxicity of a chemical are affected by environmental interactions.