Deriving the aquatic predicted no-effect concentrations (PNECs) of three chlorophenols for the Taihu Lake, China

Abstract

The Predicted No-Effect Concentration (PNEC) is a key for ecological risk assessment. In this paper, the aquatic species existing widely in the Taihu Lake were selected, and their toxicity data to 2,4-dichlorophenol (2,4-DCP), 2,4,6-trichlorophenol (2,4,6-TCP) and pentachlorophenol (PCP) were collected. The PNECs of 2,4-DCP; 2,4,6-TCP; and PCP were derived using three different approaches, i.e., the assessment factor (AF), species sensitivity distribution (SSD) as well as an eco-toxicological model (AQUATOX). As the results, PNECAFs were 2.18 μg L−1, 2.53 μg L−1 and 0.26 μg L−1, and PNECSSDs were 77 μg L−1, 197 μg L−1 and 10 μg L−1, respectively for 2,4-DCP; 2,4,6-TCP; and PCP respectively. Based on the aquatic conditions of the Taihu Lake, the derived site-specific PNECAQUATOXs were 15 μg L−1, 67 μg L−1 and 4 μg L−1, respectively. In general, the PNECs for three chlorophenols derived from different approaches followed the declined order of PNECSSD> PNECAQUATOX> PNECAF. The ratios of PNECAF to PNECSSD and PNECAQUATOX to PNECSSD for three chlorophenols were 0.013-0.028 and 0.19-0.4, respectively. It indicated that PNECs obtained using different approaches may vary and the one based on the AF was the lowest. Therefore, PNECAF can be seen as overprotective. The PNECAQUATOX values for three chlorophenols were less than the corresponding PNECSSD values, mostly because the indirect effects were considered in the ecological model.