Two-dimensional numerical, eco-toxicological modeling of chemical spills

Abstract

Chemical spills of various sizes happened everywhere in the world nowadays due to paramount production, storage, usage of chemicals. The safety and normal function of aquatic eco-system have thus been increasingly threatened by spilled chemicals. How to evaluate the effect of chemical spills on aquatic nontarget organisms has been a challenge due to the fact that aquatic eco-systems are an integrated entity with numerous organisms of varying species, body sizes and numbers. Based on a review of current three ecotoxicological models of chemical fate, i.e., ACQUATOX model of US-EPA, Hudson River Model of PCBs, and CBR model and DEBtox model, this paper presented an uncoupled ecotoxicological model in the sense that it simulates chemical transport and transformation of chemical spills and mortality of an organism caused by the chemical separately. The chemical fate was simulated by a chemical transport model. Organism killings were simulated by the extended threshold damage model, which was developed originally for experimental cases and extended here for natural water bodies. Due to extreme scarcity of data, this model was applied in a hypothetical case: a certain amount of pentachlorophenol spills upstream of a lake. Theoretical analysis and simulated results indicated that this model is capable of reasonably predicting acute effects of chemical spills on aquatic ecosystem or organism killings.