Application of microcosm and species sensitivity distribution approaches in the ecological hazard assessment of 4-tert-butylphenol

<p>In order to evaluate the ecological hazard of 4-tert-butylphenol (4-TBP), species abundances and physicochemical properties were monitored for 63 days in a microcosm system containing planktonic algae, rotifers, shrimps and <i>Daphnia</i>. The 63 days-NOEC (no observed effect concentration) of 4-TBP for this system was calculated. At the same time, species sensitivity distribution curves were constructed based on the toxicity data of EC<sub>10</sub>, EC<sub>50</sub> and NOEC derived from laboratory single-species toxicity tests, which further gives no obvious hazard concentrations for 95% species in the ecosystem (HC<sub>5</sub>). In both the microcosm and the single-species tests, the shrimp (<i>Neocaridina</i> sp<i>.</i>) was the most sensitive species to 4-TBP exposure, while most algae species were relatively insensitive compared to the zooplankton. For the microcosm exposed to 4-TBP, significant changes occurred to the community structure instead of the community function, resulting in a NOEC<sub>microcosm</sub> of 265.38 μg L<sup>–1</sup> which approached the EC<sub>10</sub>-based HC<sub>5</sub> (0.376 mg L<sup>–1</sup>). Nevertheless, EC<sub>50</sub>-based HC<sub>5</sub> was higher than the NOEC<sub>microcosm</sub>, and the NOEC-based HC<sub>5</sub> was lower. The data showed that the EC<sub>10</sub>-based HC<sub>5</sub> was protective at the similar level with the result of microcosm for 4-TBP, providing supportive data for chemical risk assessment.</p>