吳郭魚於暖化與二氧化碳酸化淡水之協同效應對奈米銅之生物累積

Synergistic effects of warming and carbon dioxide induced freshwater acidification on bioaccumulation of tilapia (Oreochromis niloticus) exposed to copper nanoparticles

郭晉良(Jin-Liang Kuo)

指導教授 ： 陳韋妤

高雄醫學大學/生命科學院/生物醫學暨環境生物學系碩士班/碩士(2018年)

摘要

近年奈米銅多應用在積體電路板及燃料電池等產品，且因大量生產及使用，導致奈米銅流入水域環境中。此外，大氣二氧化碳不斷增加，引起全球暖化和酸化現象，亦會改變奈米銅之物理及化學特性，而影響水域生物對其生物累積程度。然，前人研究多探討單一環境因子對奈米銅生物累積之效應，缺乏多重效應對其之生物累積。因此，本研究目的為評估暖化與二氧化碳酸化是否協同增加奈米銅對吳郭魚Oreochromis niloticus之生物累積。本實驗設計不同的暖化(26、28及30°C)與酸化(pHs 7.5、6.5及5.5)條件下，吳郭魚暴露於25 nm奈米銅，其濃度為0.3 mg L-1之環境，進行7天之吸收試驗，接續移至乾淨水體進行7天之排除試驗，並分析吳郭魚鰓及肌肉之銅累積程度。結果顯示鰓與肌肉在吸收期間不會受到暖化影響。然，鰓於排除期間第7天高暖化組別(30°C/pH 7.5)之累積濃度3.68 ± 0.89 µg g-1顯著高於控制組(26°C/pH 7.5)1.00 ± 0.46 µg g-1 (p<0.05)。而肌肉於排除期間第1天，高暖化組別之銅累積濃度1.63 ± 0.20 µg g-1顯著高於控制組0.61 ± 0.04 µg g-1 (p<0.05)，因此，於排除期間鰓及肌肉都會受到暖化影響導致銅濃度不易排除。酸化效應之結果顯示，鰓於吸收期間第7天，高酸化的組別(26°C/pH 5.5)之累積濃度8.75 ± 0.83 µg g-1顯著高於控制組之累積濃度5.10 ± 0.68 µg g-1 (p<0.01)，然而在排除期間第7天，所有酸化組別之銅累積濃度[弱酸化組(26°C/pH 6.5)：4.09 ± 0.32 µg g-1；高酸化組(26°C/pH 5.5)：2.89 ± 0.14 µg g-1]皆顯著高於控制1.01 ± 0.46 µg g-1 (p<0.001)。此外，肌肉於吸收期間不會受到酸化影響；然，高酸化組於排除期間第1天1.45 ± 0.12 µg g-1及第7天1.39 ± 0.16 µg g-1，皆顯著高於控制組0.6 ± 0.04 µg g-1 (p<0.001)。因此，酸化會增加吸收期間鰓之銅累積程度，然而排除期間，鰓及肌肉皆會受酸化影響導致銅濃度不易排除。鰓於多重效應下，吸收期間第1天弱暖化與弱酸化組別(28°C/pH 6.5)顯著影響鰓之累積程度(p<0.001)，直至第7天卻無顯著影響。然，在排除期間第7天，多重效應皆顯著影響鰓之銅濃度不易排除(p<0.05)。此外，肌肉在多重效應下吸收期間第1天及第7天，多重效應組別與控制組無顯著差異。而於排除期間第1天未受到多重效應影響，反而於第7天，多重效應顯著影響銅濃度之排除(p<0.01)。最後，本研究指出酸化為主要增加奈米銅對吳郭魚鰓之累積，而多重效應則協同導致排除期間鰓及肌肉之銅濃度不易排除。

關鍵字

吳郭魚 ； 奈米銅 ； 生物累積 ； 二氧化碳酸化 ； 暖化 ； 協同作用

並列摘要

Copper nanoparticles (CuNP) are widely applied in piezoelectric devices and fuel cells. Large-scale production and consumption of CuNP-containing products could lead to discharge of CuNP into aquatic ecosystems. In addition, increasing atmospheric carbon dioxide (CO2) resulted in warming and acidification of aquatic ecosystem, further affecting on physicochemical properties of CuNP and its accumulated by aquatic organisms. However, previous studies investigated the effects of single environmental factor on the CuNP bioaccumulation. The effects of multiple factors on bioaccumulation of CuNP are still unknown. The purpose of this study is to assess whether warming and CO2 induced acidification synergistically increase the bioaccumulation of CuNP in tilapia (Oreochromis niloticus). Tilapia were exposed to waterborne 25 nm CuNP for 7-day uptake and transferred to clean water for 7-day in following different environmental scenarios, combined with acidification groups (pHs 7.5, 6.5 and 5.5) and warming groups (26, 28 and 30°C), and to analyze accumulation of gill and muscle. Results indicated that warming factor did not increase accumulation of the CuNP concentration in gill and muscle for uptake phase. At 7-day depuration phase of warming experiment, the accumulated concentration of high warming group (30°C/pH 7.5) in gill was 3.68 ± 0.89 µg g-1, and significantly higher than control (26°C/pH 7.5; 1.00 ± 0.46 µg g-1, p < 0.05). Moreover, the concentration of muscle in high warming group (1.63 ± 0.20 µg g-1) was also significantly higher than control (0.61 ± 0.04 µg g-1) at 1-day depuration phase (p<0.05). It revealed that warming would slow-down the copper depuration in gill and muscle. Results of acidification effects demonstrated that the accumulated concentration of high acidification group (26°C/pH 5.5) in gill was 8.75 ± 0.83 µg g-1, which significantly higher than control (5.10 ± 0.68 µg g-1) at 7-day uptake phase (p < 0.01). However, concentration of gill in all acidification groups during depuration phase [low acidification (26°C/pH 6.5): 4.09 ± 0.32 µg g-1; high acidification (26°C/pH 5.5): 2.89 ± 0.14 µg g-1] were significantly higher than control (1.01 ± 0.46 µg g-1, p < 0.001). The acidification factor did not increase the CuNP concentration in muscle for uptake phase, whereas the concentrations of high acidification group at 1- and 7-days of depuration phase were 1.45 ± 0.12 µg g-1 and 1.39 ± 0.16 µg g-1, respectively, and significantly higher than control (0.6 ± 0.04 µg g-1, p < 0.001). Therefore, acidification would increase the copper uptake in gill, and slow down the copper depuration in gill and muscle. Under multiple factors scenarios, the low warming and acidification (28°C/pH 6.5) significantly affected the bioaccumulation of CuNP in uptake phase (p < 0.01), but there was no effect at 7 days. The multiple factors would also significantly slow down the copper depuration in gill (p < 0.05). Moreover, there was no significantly difference among CuNP concentration of control and multiple factors groups in muscle at 1- and 7-days of uptake phase. In depuration phase, multiple factors significantly affected the accumulated concentrations at 7-day (p < 0.01), but did not at 1-day. In conclusion, this study suggested that acidification mainly increases the bioaccumulation of CuNP in tilapia, and multiple factors synergistically retard the depuration of CuNP in gill and muscle for depuration phase.

並列關鍵字

Tilapia ； Copper nanoparticles ； Bioaccumulation ； Carbon dioxide induced acidification ； Warming ； Synergistic

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