无机砷在牟氏角毛藻中的化学行为及其毒理效应

发布时间：2018-05-05 01:41

本文选题：无机砷 + 牟氏角毛藻　；参考：《上海海洋大学》2017年硕士论文

【摘要】：砷是一种较常见且持久性的污染物,可以被海洋生物富集并通过食物链传递,海产品中的高含量砷已引起人们的普遍关注。砷在海洋环境中有多种存在形态,主要分为无机砷和有机砷两大类,其对海洋生物的毒性作用受砷形态的影响,不同砷形态的化合物毒性各不相同,现在一般认为砷的毒性级别是无机砷有机砷,无机砷中As(III)As(V),但是对于不同生物砷化物的毒性也存在一定特异性。牟氏角毛藻(Chaetoceros mulleri)作为海洋浮游植物中的优势种群,可以对环境变化快速响应,是研究海洋环境污染与全球气候变化的重要生物种类,具有重要的研究价值。本文研究了无机砷As(III、V)暴露及其与海水酸化耦合对牟氏角毛藻生长、光合的影响,查明了牟氏角毛藻对无机砷的富集与转化及其基因组DNA甲基化水平的变化。主要结果如下:1、无机砷暴露对牟氏角毛藻生长、光合作用的影响。(1)对其生长的影响:As(III)暴露使牟氏角毛藻生长率随着时间呈下降趋势,暴露浓度低于1000μmol/L时,牟氏角毛藻生长率随砷浓度的升高呈下降趋势;浓度高于1000μmol/L时,在初期牟氏角毛藻生长率随砷浓度升高而升高,随着实验进行,生长率下降。300μmol/L As(III)暴露48h时,藻体生长率降至0以下。(2)对其叶绿素a含量和叶绿素荧光参数的影响:As(III)暴露使牟氏角毛藻叶绿素a含量随时间下降,但是变化不显著(P0.05);而随着砷浓度升高,叶绿素a含量整体呈下降趋势;As(III)暴露浓度低于70μmol/L条件下,牟氏角毛藻最大光能转化效率(Fv/Fm)和实际光能转化效率(Yield)随时间变化不显著,但砷浓度高于70μmol/L时对藻细胞荧光参数有显著的抑制作用。As(V)暴露同样导致牟氏角毛藻的生长率随着时间呈下降趋势。低浓度As(V)对牟氏角毛藻生长率无明显影响,且As(III)暴露浓度在120μmol/L时,藻的生长率迅速下降,在浓度为300μmol/L时又缓慢上升。但在实验浓度范围内,As(V)暴露时,牟氏角毛藻生长率均大于0;而对叶绿素a含量和叶绿素荧光参数都无显著影响。结果表明,无机砷As(III)和As(V)对牟氏角毛藻的生长具有不同的影响,其抑制作用表现为As(III)As(V)。2、无机砷与海水酸化共同作用对牟氏角毛藻生长、光合作用的影响。(1)As(III)与海水酸化共同作用对牟氏角毛藻生长、光合作用的影响:As(III)暴露与海水酸化耦合作用于牟氏角毛藻时,藻的生长率随CO2浓度升高而升高,但是升高的趋势随As(III)浓度的增加越来越弱。当海水酸化单独作用时,牟氏角毛藻中叶绿素a的含量和荧光参数Fv/Fm和Yield无显著变化;当与As(III)共同作用条件下,通入1000ppm CO2时,藻体中叶绿素a含量随时间变化波动较大,且随As(III)浓度升高荧光参数Fv/Fm和Yield明显下降,但下降的趋势减弱。(2)As(V)与海水酸化共同作用对牟氏角毛藻生长、光合作用的影响:As(V)暴露与海水酸化耦合作用时,藻的生长率和叶绿素a含量在砷试验范围内无显著变化,而叶绿素荧光参数Fv/Fm和Yield在As(V)暴露96h时表现为随CO2浓度增大而显著下降。结果表明,海水酸化可以促进牟氏角毛藻的生长,无机砷与海水酸化共同胁迫时,这种促进作用减弱;在低浓度无机砷时,叶绿素荧光参数Fv/Fm和Yield降低,但是所有实验中As(III)对藻细胞生长和叶绿素荧光参数的抑制作用均比As(V)强。3、牟氏角毛藻对无机砷的生物富集与形态转化。As(III)暴露时,牟氏角毛藻对砷的富集量总体上随As(III)浓度的增大而增加,但是在As(III)浓度为100μmol/L时下降。牟氏角毛藻中砷的富集量y(μg/105cells)与暴露As(III)的浓度x(μmol/L)可推导为二次多项式y=8×107x2+0.004x+3.3143。在96h,在较低暴露浓度组(50-300μmol/L),藻细胞中As(V)占总砷的比例随着暴露浓度的升高呈增加的趋势;但在高浓度组(500-7000μmol/L),随着暴露浓度增加藻细胞中As(V)的比例变化不明显,但1000μmol/L暴露组为最大值。As(V)暴露时,牟氏角毛藻中砷的富集量y(μg/105cells)与暴露As(V)的浓度x(μmol/L)也可推导为二次多项式方程y=-1×10-5x2+0.078x+13.015,在实验浓度范围内富集量最大值达171.10μg/105cells。牟氏角毛藻对As(V)形态的转化作用不明显。4、无机砷暴露对藻细胞基因组DNA甲基化水平的影响。研究表明,一定浓度范围的As(III、V)暴露可以引起DNA甲基化水平明显升高,但长期暴露高浓度As(III)后DNA甲基化水平则与对照无显著差异。
[Abstract]:Arsenic is a more common and persistent pollutant, which can be enriched by marine organisms and passed through the food chain. The high content of arsenic in marine products has attracted widespread attention. Arsenic in the marine environment is mainly divided into two major categories: inorganic and organic arsenic. The toxicity of arsenic to marine organisms is affected by arsenic form. The toxicity of the compounds with different arsenic forms is different. Now it is generally believed that the toxicity grade of arsenic is organic arsenic of inorganic arsenic, As (III) As (V) in inorganic arsenic, but it also has certain specificity for the toxicity of different biological arsenide. The Chaetoceros mulleri (Chaetoceros mulleri) is the dominant species in marine phytoplankton, and can change the environment quickly. The rapid response, which is an important biological species for the study of marine environmental pollution and global climate change, has important research value. In this paper, the exposure of As (III, V) and its coupling with sea water acidification on the growth and Photosynthesis of M. montae were studied, and the enrichment and transformation of the inorganic arsenic in monk's horn and its genomic DNA methylation water were found out. The main results were as follows: 1, the effect of the exposure of inorganic arsenic on the growth and Photosynthesis of monzolus monkhae. (1) the growth rate of As (III) exposure made the growth rate of Mu's horns descended with time and the exposure concentration was lower than 1000 u mol/L, and the growth rate of Mao Zao of monkhorus monkhorus decreased with the increase of arsenic concentration; the concentration was higher than 1000. In the initial stage, the growth rate of Mu mol/L increased with the increase of arsenic concentration. When the experiment was carried out, the growth rate of.300 mu mol/L As (III) was reduced to less than 0. (2) the effects of the chlorophyll a content and chlorophyll fluorescence parameters on its chlorophyll a content and chlorophyll fluorescence parameters: As (III) exposure made the content of chlorophyll a content decreased with time, but changed, but changed with time. However, the content of chlorophyll a decreased with the increase of arsenic concentration, and the maximum light energy conversion efficiency (Fv/Fm) and actual light conversion efficiency (Yield) of As (III) exposed to As (III) were not significant, but the fluorescence parameters of algae cells were significantly higher than that of 70 u mol/L when the concentration of As (As) was higher than that of the time. The inhibitory effect of.As (V) exposure also resulted in a downward trend in the growth rate of monzolus monzoliti with time. Low concentration of As (V) had no obvious effect on the growth rate of Mu's horn, and when As (III) exposure concentration was 120 u mol/L, the growth rate of algae declined rapidly and increased slowly at the concentration of 300 u mol/L, but in the range of experimental concentration, As (V) was exposed, The growth rate of Mu's angle hair algae was greater than 0, but had no significant influence on chlorophyll a content and chlorophyll fluorescence parameters. The results showed that inorganic arsenic As (III) and As (V) had different effects on the growth of Mu's horn. The inhibition effect was As (III) As (V).2, and the combination of inorganic arsenic and seawater acidification on the growth and Photosynthesis of monk's horn (1) (1) the effect of As (III) and seawater acidification on the growth of Mu's horns and the effect of photosynthesis: when As (III) exposure and sea water acidification are used for the use of the alga monkspa, the growth rate of the algae increases with the increase of CO2 concentration, but the trend of the increase is weaker with the increase of As (III) concentration. There was no significant change in the chlorophyll a content and the fluorescence parameters Fv/Fm and Yield of Mao Zaozhong. When the As (III) was combined with 1000ppm CO2, the content of chlorophyll a in the algae fluctuated with the time, and the fluorescence parameter Fv/Fm and Yield decreased with the increase of As (III) concentration, but the decline was weakened. (2) together with the acidification of sea water The effect on the growth and Photosynthesis of Mu's horn: when As (V) exposure is coupled with the acidification of sea water, there is no significant change in the growth rate of algae and the content of chlorophyll a in the range of arsenic test, while the chlorophyll fluorescence parameters Fv/Fm and Yield significantly decrease with the increase of CO2 concentration when As (V) is exposed to 96h. The results show that the acidification of sea water can be obtained. To promote the growth of Mu's horn, the promotion effect was weakened when the inorganic arsenic and sea water acidification were co coercion, and the chlorophyll fluorescence parameters Fv/Fm and Yield decreased in the low concentration of inorganic arsenic, but the inhibitory effect of As (III) on the growth of algae cells and the chlorophyll fluorescence parameters in all experiments were stronger than that of As (V), and the production of inorganic arsenic from monzolus monacolus. The concentration of.As (III) increased with the increase of As (III) concentration, but decreased when the concentration of As (III) was 100 mu mol/L. The concentration x (mu g/105cells) of Mao Zaozhong arsenic in Mu's angle and the concentration x (MU) of exposed As (III) could be deduced to two times polynomial. In 96h, the ratio of As (V) to total arsenic in the algal cells increased with the increase of exposure concentration in the lower exposure concentration group (50-300 mu mol/L), but in the high concentration group (500-7000 mu mol/L), the proportion of As (V) in the algal cells increased with the increase of exposure concentration, but the 1000 mu mol/L exposed group was the maximum.As (V) exposure, in the monk's horn. The concentration of arsenic concentration y (mu g/105cells) and exposed As (V) concentration x (mu mol/L) can also be derived from the two polynomial equation y=-1 x 10-5x2+0.078x+13.015. The maximum concentration of the concentration in the experimental concentration range is 171.10 mu. The transformation of As (V) is not obvious, and the inorganic arsenic exposure to the genome of the algae cell genome is not obvious. The study showed that the level of As (III, V) exposure in a certain concentration range could cause a significant increase in the level of DNA methylation, but the level of DNA methylation was not significantly different from that of the control after long-term exposure to high concentration of As (III).

【学位授予单位】：上海海洋大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X173;X171.5

【参考文献】