Assessing copper and lead interaction in contaminated sediments and their bioavailability and toxicity to larvae and embryos of medaka
| Autor: | Chia-Hua Lee, 李佳樺 |
|---|---|
| Rok vydání: | 2019 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 107 In the river system, sediment is considered as a long-term source of contaminants for aquatic organisms due to its high accumulating capacity. Among all contaminants, heavy metals are of high concern because of their non-biodegradable nature. The bioavailability of these metals may be affected by sediment properties, transportation behavior between sediment-water system and physiology of aquatic organisms. To understand the chemical and biological interaction of sediment-bound contaminants to the aquatic life, this study used the whole-sediment exposure method with intermittent water renewal system to evaluate the bioavailability and toxicity of two heavy metals [i.e. lead (Pb) and copper (Cu)]. Medaka (Oryzias latipes) embryos and larvae, which were used as model organisms, were exposed to a variety of Pb- and Cu-spiked sediments with different physicochemical properties for 7 days to evaluate the toxicity and bioavailability. Moreover, this study discussed the transportation and effect in the sediment between these two metals. The physiochemical properties of four sediments were totally different. ZZ sediment and WS sediment were sand, TS sediment was loamy sand and WB was loam. In these sediments, WB had the highest CEC, as well as ZZ and WS has lower OC. pH value from high to low were TS > WS > ZZ > WB. Survival rates of both treated embryos and larvae from TS were the highest, and those from ZZ were the lowest. As such, we believed that metals in lower pH, CEC, OC and more sandy sediment were more releasable, and larvae were more sensitive to metal toxicity than embryos. Moreover, the larval morphology i.e. body length and body weight in dual metal spiked sediments groups were significantly inhibited in very low concentrations. The trend of larval mortality spiked with single Cu into ZZ sediment was similar to that with dual metal at in same Cu concentration. Based on the results, the lethal toxicity was mainly affected by Cu, as the bioavailability of Pb was low. In this study, we also used several analytical approaches to assess the bioavailability of these two metals and the correlation (log-logistic model and linear regression) with observed toxic effects. The resuls showed that Chelex-100 resin extraction method can be an effective method for predicting and evaluating bioavailability of sedimental Cu and Pb to medaka no matter in single or dual metal polluted sediment. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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