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Thesis Advisor潘响亮
Degree Grantor中国科学院大学
Place of Conferral新疆乌鲁木齐
Degree Discipline工程硕士
Keyword蓝藻水华 H2O2 铁盐催化 胞外聚合物 cyanobacterial bloom H2O2 ferric salt EPS
AbstractCyanobacterial bloom is one of the hot environmental issues which should be resolved for domestic and international researchers. Many freshwater lakes in China at present are in a state of moderate or severe eutrophication, and faced with blooms outbreak constantly, H2O2 has strong oxidizing properties, and can generate strong killing-effect to water bloom cyanobacteria, the final products are H2O and O2, which will not cause environmental pollution. Ferric salts can catalyze H2O2 to generate much more ·OH, consequently enhance the oxidation properties significantly, therefore a small amount of iron addition can not only reinforce the algae-killing effect of H2O2, but also save the dosage of H2O2, this process provides a new approach for the control of water bloom cyanobacteria.Dominant species include many common and specific water-blooming cyanobacteria when the blooms break out in china lakes, and the algicidal effect of H2O2 to specific water-blooming cyanobacteria is different. the catalysis of ferric salt and light is quite important during controlling algal bloom, and exopolymers also play a key role in the algicidal process of H2O2, it’s therefor necessary to study the impact of above-mentioned factors.the aim of this research is to investigate the algicidal effect of H2O2 with organic and inorganic iron as a catalyst. Chlorophyll fluorescence Fv/Fm is regarded as an index, this assay also studies the function and changes of extracellular polymers(EPS) and cell membrane during H2O2 killing the cyanobacteria by batch experiments , the main results were as follows:(1) The effectiveness of iron salts is assessed by Chlorophyll fluorescence, the algicidal effect of H2O2 is ralatively poor with FeSO4 as catalyst, while the effect of H2O2 to kill algae under light with EDTANaFe as catalyst is quite good. Light radiation can significantly enhance the algicidal effect of H2O2 in the process of algae control.(2) Algae-killing effect of H2O2 with FeSO4 as catalyst is not good, the reason is summarized as follows; at neutral or slightly alkaline condition, Fe2+ is oxidized into Fe3+ and the partical size of solution increases, consequently forming precipitation when adding FeSO4, and leading to interruption of Fenton reaction, while EDTANaFe can keep the iron at the state of complexation, and mantain the Fenton reaction.(3) By comparison of killing effect between main eight kinds of cyanobacteria with H2O2 using EDTANaFe as catalyst, we find that the algicidal effect of H2O2 differences along with various algae, Microcystis ichthyoblabe is scarcely damaged by H2O2 and EDTANaFe(H2O2=10 mg L-1, Fe2+=3 mg L-1), Microcystis aeruginosa is also not easy to damaged by H2O2 and EDTANaFe, while other cyanobacterias are strongly damaged by H2O2 and EDTANaFe .(4) Extracellular polymers (EPS) play an important role when H2O2 kills algae, cyanobacteria cells without EPS are quite sensitive to H2O2, but the damage of H2O2 to them is still different among the species. As for Microcystis ichthyoblabe, H2O2(10mg L-1) has little impact on it even though the aglae has been extracted EPS, but for other algaes, the decline in Fv/Fm of Cell-EPS is 1.5~2 times of that of Cell+EPS after adding same H2O2, which shows that EPS could scavenge about half of H2O2. (5) H2O2 can increase the permeability of cell menbrane as well as damage the cell membrane, and the level of damage is positively correlated with the decilne in Fv/Fm, therefore the permeability change of cell membrane can be regard as an index of damaging to algae(6) TOC changes little during the algicidal process by low-concentration H2O2, while half of protein and parts of polysaccharide are suffered structure changes including the decrease in molecule weight .
Other Abstract蓝藻水华是国内外亟待解决的重大环境问题之一,我国目前很多湖泊处于中度甚至重度富营养化状态,时刻面临水华爆发的威胁。H2O2具有强氧化性,能够对水华蓝藻产生很强的灭杀效果,最终产物是H2O和O2,铁盐能够催化H2O2产生更多的·OH,使得其氧化效果显著增强,因此加入少量的铁盐就能增强H2O2的杀藻效果,同时也能够节省H2O2的用量,本身不会对环境造成太多污染,该过程为水华蓝藻的治理提供了一种新的思路和方法。我国不同湖泊爆发蓝藻水华时其优势种包括很多常见的水华蓝藻却又不尽相同,H2O2对不同水华蓝藻的杀伤效果也不尽相同;在H2O2杀藻过程中,铁盐的催化和光照催化起到重要的作用,同时胞外聚合物(EPS)也扮演着及其重要的作用。本论文以有机铁和无机铁作为催化剂,以叶绿素荧光最大光量子产率Fv/Fm为指标,通过批实验,研究了铁盐催化H2O2对主要水华蓝藻的灭杀效果;通过荧光探针、激光共聚焦成像、红外光谱和高效液相色谱等手段研究了EPS和细胞膜在H2O2杀藻过程中的作用和变化,主要研究结果如下:(1)通过叶绿素荧光的技术手段,确定无机铁盐FeSO4催化H2O2杀藻效果较差,而有机铁盐EDTANaFe催化H2O2在光照下杀藻效果良好。在H2O2杀藻过程中,光照能够显著增强H2O2的杀藻效果。(2)FeSO4催化H2O2杀藻效果较差的原因是在中性或弱碱性条件下,Fe2+被氧化成Fe3+后,粒径增大,形成沉淀颗粒,很难再次被还原为Fe2+,导致Fenton反应不能持续下去,而EDTANaFe能够始终使铁保持络合状态,维持Fenton反应的发生。(3)利用EDTANaFe催化H2O2对主要的8种蓝藻进行灭杀效果对比,发现各个蓝藻之间存在差异,在设定浓度下(H2O2=10 mg L-1,Fe2+=3 mg L-1)H2O2几乎不会对鱼害微囊藻造成影响,铜绿微囊藻也不容易被杀死,其它蓝藻较容易被杀死并且灭杀效果相差不大。(4)EPS对H2O2杀藻效果产生重要影响,分离掉EPS的蓝藻细胞对H2O2变得非常敏感,但是不同蓝藻即使去除EPS,H2O2对其灭杀的效果仍然有差异。对于鱼害微囊藻,即使去除EPS,10mg L-1的H2O2仍然对其影响不大,对于其它蓝藻藻株,把没有去除EPS加入H2O2的藻液看作对比组,去除EPS再加入H2O2的处理组测定的Fv/Fm下降值是对比组的1.5~2倍,说明EPS大约能清除一半左右的H2O2毒害作用。(5)H2O2的加入能够使细胞膜渗透性变大,或者使细胞膜受损,受损程度与叶绿素荧光Fv/Fm值下降关系比较统一,细胞膜渗透性变化的大小,可以认为是H2O2对各种蓝藻杀伤程度的衡量指标之一。(6)在低浓度H2O2杀藻过程中,胞外聚合物的TOC变化不大,但是有一半左右的蛋白质类物质结构会发生变化,多糖类物质也会被部分降解,其中H2O2的加入能够将大分子组分打碎成较小分子量的物质。
Subject Area环境工程
Document Type学位论文
First Author Affilication中国科学院新疆生态与地理研究所
Recommended Citation
GB/T 7714
李雷. H2O2杀灭水华蓝藻效率优化及胞外聚合物作用分析[D]. 新疆乌鲁木齐. 中国科学院大学,2017.
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