| Summary: | 碩士 === 國立臺灣大學 === 環境工程學研究所 === 102 === Nanoscale zero-valent iron (NZVI) has been used for the remediation of contaminated groundwater as a reductant. In order to enhance its mobility, NZVI has been surface-modified with polymers or surfactants to increase its stability in aqueous phase. Hydrophobic modifiers will also improve the affinity of NZVI with non-aqueous phase liquids. Although great amount of NZVI may be to release to the environment, the fate and ecotoxicological effects of NZVI remain unclear. In this study we investigated the toxicity of bare NZVI, polyacrylic acid (PAA), polymethylmethacrylate (PMMA) or cetyltrimethylammonium bromide (CTAB) modified NZVIs in different solution phases, Fe2O3 nanoparticles and Fe2+ on nematodes, Caenorhabditis elegans (C. elegans), by using different toxic endpoint such as lethality, reproductivity and morphological change. Under acute exposure (24 h), C. elegans were slightly affected by various types of NZVI suspensions, Fe2O3 and Fe2+. After 48h of exposure, the lengths of C. elegans were affected by all types of NZVI suspensions, as well as Fe2+ solution. After 72h of expose, the reproductivity of C. elegans was significantly decreased by NZVI suspensions and Fe2+ solution. Fe2O3 showed no toxicity to C. elegans. We have also observed the ‘bag of worms’ phenotype, which is characterized by failed egg-laying and may occur in the stressed environment which is produced by the oxidation of NZVI and the release of Fe2+ and reactive oxygen species. From the observation under the microscope, we found that NZVI particles were attached on C. elegans and inside its intestinal track which would react with internal substances and produce ROS causing the toxicity. The experimental results showed that although the stable NZVIs may not cause death in C. elegans, but it does pose adverse effects other than death, which are the potential impact of NZVI.
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