Abstract
Aquatic microcosm tests were performed to determine the ecotoxicological effect of alcohol ethoxylate (AE, C12, EO7). Compared with the control system, the population did not decrease in the system with 2 mg•L-1 AE. In the systems with 10 and 25 mg•L-1 AE, the population of fewer species decreased but recovered immediately. A massive decrease or increase in the population was observed in the systems with 50 and 100 mg•L-1 AE, and the microcosm compositional balance was changed. Through the analysis of production (P) and respiration (R) using the change in the dissolved oxygen concentration in the microcosm, it was found that the system with 2 mg•L-1 AE showed no significant difference from the control. However, there were significant differences in the 10 and 25 mg•L-1 systems. Thus, it can be judged that the AE has an effect when its concentration is over 10 mg•L-1. In addition, the ecosystem function recovered at the second day after the addition of 10 mg•L-1 AE and at the seventh day after the addition of 25 mg•L-1 AE. The ecosystem function was not recovered after 14 days in the systems with 50 and 100 mg•L-1 AE. These results suggested that the measurements of P and R could be used to evaluate the equivalent population transition. The no-observed-effect concentration of the microcosm in this study has a high correlation with the results determined by the mesocosm test.
