Chapter 4 - Eco-Risk Assessments for Toxic Contaminants Based on Species Sensitivity Distribution Models in Lake Chaohu, China

Abstract

Abstract The concentrations of 16 priority polycyclic aromatic hydrocarbons (PAHs) and 18 organochlorine pesticides (OCPs) were measured in the surface water of Lake Chaohu, China. Based on the species sensitivity distribution (SSD) model and the probabilistic risk assessment (PRA) model, the indicators were calculated to assess the potential ecological risk of individual and multiple congeners of PAHs and OCPs and their probabilities. The results revealed that the average residual level of the total PAHs (PAH 16 ) in the water ranged from 95.2 to 370.1 ng/l, with a mean value 181.5 ± 70.8 ng/l, dominated by the low-molecular-weight congeners. The annual mean concentration for the OCPs in Lake Chaohu was 6.99 ng/l, including HCHs with a mean concentration of 1.76 ng/l and DDTs of 1.91 ng/l. The multi-substance potentially affected fractions (msPAFs) of the studied PAHs obtained by the SSD, from heavy to light, followed the inflow rivers (0.93%) > western (0.42%) > eastern (0.34%) lake, while similar sequence was found for OCPs. The same order of ecological risks calculated by the two models was found for the studied PAH compounds. The toxicity data might be the primary source of the ecological risk uncertainties, indicated by the greater values of coefficients of variation (CVs) for the toxicity. The combinations of multiple indicators based on the SSD and PRA models for the ecological risk assessment are necessary to provide more general information on the spatial variations and the probabilities of potential ecological risks of the individual and multiple congeners of PAHs.