| Summary: | 碩士 === 國立屏東科技大學 === 環境工程與科學系所 === 102 === This study utilized freshwater amphipods (Hyalella azteca) as the sediment toxicity test species for testing sediment-associated contaminants in order to screen for contamination risk levels in the Erren River (ER1~ER10) and San Ye River (SY1~SY5).In addition, toxicity identification evaluations (TIE)involving the manipulation of whole sediment and porewater samples were conducted to identify causative contaminants. Impacts to the aquatic environment were then evaluated in order to explore how industrial development led to contaminants accumulating in sediments and the biological effects that can result. Furthermore, biological impacts from accumulation or biomagnification in the aquatic food chain were explored. Whole-sediment TIE indicated that the major toxicant at sampling sites ER8 and SY5 was ammonia and that its toxicity was significantly reduced by the addition of zeolite. Toxicity at sampling sites ER4 and ER9 was induced by ammonia and heavy metals (Zn, Cd, Cr, As),where as metallic Cr was at toxic levels at ER6. Furthermore, the major toxic contaminant in porewater at ER8 was ammonia, and again zeolite significantly reduced its levels. Toxicity at sampling sites ER2 was induced by ammonia and ΣPAHs at sampling sites ER3, SY1, and SY3, and is caused by heavy metals (Zn, Ni, Pb, Cd, Cr, As) identified by adding a chelating agent (EDTA). TIE can be used to confirm that a causative toxicant has been correctly identified and quantitatively correlate its measured toxicity to its concentration. This study revealed that different compounds (organic or inorganic) in whole sediment and porewater are highly characteristic of specific toxicants; however, other factors, chemicals, or organic carbons defy identification and are still cryptic. Due to the different toxicities of whole sediment and porewaters, TIE studies conducted to assess risks and correlations are discussed in order to reveal the causes of toxicity.
|
|---|
