| 英文摘要 |
A TRIAD risk assessment project was carried out for the Daan (DA1~DA3) and Erren River (SYR, SY1 and SY2) basins, which included chemical analyses (16 regulated PAHs in sediment quality guidelines), toxicity (Daphnidae, Chironomidae, and Amphipoda), and ecological evaluations (evenness index, abundance index, diversity index, and Hilsonhoff family biological index). The main objective of this project was to understand the applicability of an integrated approach to assess the ecological risks from contaminated sediments in different regions of Taiwan during different seasons.
For the dry season, the analytical results for 16 PAHs in all sediment samples were lower than the SQG-low values. In the wet season, the concentrations of the 13 PAHs were all below the SQG-low values, with the exception of four PAHs detected at site SY2, namely Ant, DBA, Flu and Phe with concentrations between the SQG-low and SQG-high values.
The results of toxicity testing showed that (1) the survival rates of D. magna exposed to porewater at all sampling sites were greater than 80%; an exception was station SY2 with 30% mortality (dry season) and 25% mortality (wet season); (2) in the wet season, the endpoints of five different biological tests at sampling station DA1 revealed chronic toxicity effects only in C. riparius; (3) at station DA2, the effect of chronic toxicity on the growth of H. azteca was significantly different from the control group (p < 0.05), and the endpoint survival rate of the chronic C. riparius test were on average 20% lower than the control group; and (4) no toxic effects were shown during acute and chronic toxicity testing for H. azteca and C. riparius at station DA3. Except for head capsule width index of C. riparius at site SY2, the toxicological endpoints survival rate of the chronic toxicity test of C. riparius from the Erren River sites was significantly different from the control. In the ecological survey, four families and seven species of fish and 45 orders and 61 species of aquatic species were recorded from the Daan River. A total of 40 species belonging to 55 families were recorded from the Erren River. Ecological assessment indices such as Shannon-Weaver, Evenness, EPT, and the Hilsonhoff family were evaluated. Our results showed that the Daan River was relatively less polluted than the Erren River.
In our survey, the three-tiers evaluation results of the integrated weight data for sediment quality (chemical, toxic, and ecological) showed that the frequency of the significant adverse effects on the aquatic ecosystem caused by sediment contamination at stations DA1~DA3 were 0 %, 25%, and 75%, respectively. Only one result showed no adverse effects at station DA1 during the wet season investigation in 2020. As for the Erren River, the sediment contamination indicated at SYR, SY1 and SY2 stations with 33%, 100%, and 100%, respectively, posed significant adverse effects, respectively. The results showed that the potential ecological risk for the Erren River watershed was higher than that of the Daan River watershed, and the pollution levels of both watersheds were increasing from the upstream to the downstream. Overall, compared to the traditionally used single aspect of sediment quality guideline, TRIAD can provide a more comprehensive and integrative contamination survey that combines chemical, toxicity, and ecological risk evaluations of sediments and their porewaters.
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