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Aquatic ecosystems are often polluted with more than one type of contaminant, and information on the combined toxic effects of mixed pollutants on aquatic organisms is scarce at present. Acute toxicity of aromatic compounds and their ternary mixtures to the alga (Scenedesmus obliquus) was determined by the algae growth inhibition test. The median effective concentration (EC50) value for a single aromatic compound and EC50mix values for mixtures were obtained. the logarithm of n-octanol/water partition coefficient (logPmix) and the frontier orbital energy gap (ΔEmix) for mixtures were calculated. Based on the quantitative structure-activity relationship model for single chemical toxicity log(1/EC50) =0.426logP -1.150ΔE +12.61 (n=15, R2=0.917 and Q2=0.878), the following two-descriptor model was developed for the ternary mixture toxicity of aromatic compounds: log(1/EC50mix)=0.682logPmix-0.367ΔEmix+ 4.971 (n=44, R2=0.869 and Q2=0.843). This model can be used to predict the combined toxicity of mixtures containing toxicants with different mechanisms of action.
Aquatic ecosystems are often polluted with more than one type of contaminant, and information on the combined toxic effects of mixed pollutants on aquatic organisms is scarce at present. Acute toxicity of aromatic compounds and their ternary mixtures to the alga (Scenedesmus obliquus) was determined by the median effective concentration (EC50) value for a single aromatic compound and EC50mix values for mixtures were obtained. the logarithm of n-octanol / water partition coefficient (logPmix) and the frontier orbital energy gap (ΔEmix) for Based on the quantitative structure-activity relationship model for single chemical toxicity log (1 / EC50) = 0.426 logP -1.150 ΔE +12.61 (n = 15, R2 = 0.917 and Q2 = 0.878), the following two-descriptor model was developed for the ternary mixture toxicity of aromatic compounds: log (1 / EC50mix) = 0.682 log Pmix-0.367 Δ Emix + 4.971 (n = 44, R2 = 0.869 and Q2 = 0.843). This model can be used to predict the combined to xicity of mixtures containing toxicants with different mechanisms of action.