我国民营企业社会责任披露活动案例研究毕业论文_会计学毕业论文

我国民营企业社会责任披露活动案例研究毕业论文

2021-04-08更新

摘 要

近年来全国各地的湖泊、河流、水库等水质资源都不同程度的受到大面积爆发藻类的影响,有害的藻类对于人类生活如水产养殖业、供水行业等都有着一定的危害,同时也破坏了水域的景观生态平衡,产生一系列严重的环境、经济和社会问题。目前常见且较受关注的淡水水华优势种是铜绿微囊藻(Microcystis aeruginosa),其产生的微囊藻毒素具有极强的致肝癌性,并且微囊藻毒素可通过食物链进行富集进而影响人类及其他动物的健康,危害极大。因此,如何有效地控制富营养化水体中有害藻类水华的爆发成为当前环境工作者研究的热点及前沿问题。

近些年来,研究发现植物之所以能够对藻类生长产生抑制作用,是因为植物会分泌化感物质,而这些物质就是抑制藻类生长的根源。实验采用生长对数期的铜绿微囊藻样本,分别在不同浓度的丁二酸条件下培养,每隔24小时对其早细胞密度、叶绿素a浓度、叶绿素荧光参数以及上清液中蛋白质和核酸的含量进行测定。

结果显示,低浓度的丁二酸对铜绿微囊藻的光合作用并没有明显影响,当化感物质丁二酸的浓度达到60mg/L时,藻密度显著降低,叶绿素a含量显著下降,藻细胞最大光化学效率降低,五天后藻细胞死亡;高浓度的丁二酸会对细胞膜产生损伤导致细胞内蛋白质和核酸外泄。研究表明,当丁二酸浓度较高时,铜绿微囊藻受到胁迫,光合作用被抑制。

本研究旨在通过研究梭鱼草(Pontederia cordata L.)根茎提取物丁二酸对铜绿微囊藻光合作用的影响,探索水生植物的化感抑藻机理,为当今合理利用水生植物控制蓝藻水华的大面积生长和开发生态安全的植物源抑藻剂等实践提供坚实的理论基础。

关键词:丁二酸;化感作用;铜绿微囊藻;光合作用

Effects of rhizome extraction of Pontederia cordata L. on photosynthesis of Microcystis aeruginosa

ABSTRACT

In recent years, water resources such as lakes, rivers, and reservoirs all over the country have been affected by large-scale algal blooms in varying degrees. Harmful algae have certain harms to human life such as aquaculture and water supply industries, and it also destroys the landscape ecological balance of the waters which produces a series of serious environmental, economic and social problems. Microcystis aeruginosa is a common and more popular species of freshwater blooms, the microcystins produced by them have strong liver cancer resistance. And microcystins can be enriched through the food chain and affect the health of humans and other animals. Therefore, how to effectively control the outbreak of harmful algal blooms in eutrophic water has become a hot topic and frontier problem for current environmental workers.

In recent years, studies have found that plants can inhibit algae growth because plants secrete sensitizing substances, which are the roots that inhibit algae growth. The experiment used a logarithmic phase of Microcystis aeruginosa samples, which were cultured under different concentrations of succinic acid. Their early cell density, chlorophyll a concentration, chlorophyll fluorescence parameters and supernatant proteins and nucleic acids were observed every 24 hours.

The results showed that the low concentration of succinic acid had no significant effect on the photosynthesis of Microcystis aeruginosa. When the concentration of allelochemical succinic acid reached 60mg/L, the algae density decreased significantly, the chlorophyll a content decreased significantly, the maximum photochemical efficiency of algae cells decreased, and the algae cells died after five days; the high concentration of succinic acid caused damage to the cell membrane, which leads to the leakage of proteins and nucleic acids in cells.Studies have shown that when the concentration of succinic acid is high, Microcystis aeruginosa is stressed and photosynthesis is inhibited.

The purpose of this study was to investigate the effects of succinic acid extracted from the rhizome extract of Barracuda grass on the photosynthesis of Microcystis aeruginosa, and to explore the allelopathic mechanism of aquatic plants, and to control the large-scale growth of cyanobacterial blooms for rational use of aquatic plants. And it provides a solid theoretical basis for the practice of rational use of aquatic plants to control the large-scale growth of cyanobacterial blooms and the development of ecologically safe plant-derived algaecides.

Key words:Succinic acid; Allelopathy; Microcystis aeruginosa; Photosynthesis

目 录

1 绪论 1

1.1 藻类水华的成因 1

1.1.1 蓝藻水华及其特征 1

1.1.2 藻类水华形成原因 1

1.2 铜绿微囊藻概述 1

1.2.1 铜绿微囊藻生物学特性 1

1.2.2 铜绿微囊藻水华的危害 2

1.2.3 控制铜绿微囊藻水华的手段 2

1.3 水生植物化感抑藻相关进展 2

1.3.1 植物化感物质对藻类的抑制作用 3

1.3.2 植物化感物质抑藻机理 4

1.3.3 常见植物化感物质 4

1.4 本实验的研究目的及意义 5

1.5 研究内容 6

2 材料与方法 6

2.1 实验材料 6

2.1.1 藻种 6

2.2.2 化感物质 6

2.2 实验指标的测定 7

2.2.1 不同浓度的丁二酸对藻细胞密度的影响 7

2.2.2 不同浓度的丁二酸对叶绿素a浓度的影响 7

2.2.3 不同浓度的丁二酸对荧光动力学曲线以及荧光参数的影响 8

2.2.4 细胞膜完整性的测定 8

2.2.5 数据分析 8

3 结果与分析 9

3.1 不同浓度的丁二酸对藻细胞密度的影响 9

3.2 不同浓度的丁二酸对叶绿素a浓度的影响 10

3.3 不同浓度的丁二酸对荧光动力学曲线以及荧光参数的影响 11

3.4 细胞膜完整性的测定 12

4 讨论与结论 13

4.1 梭鱼草根茎具有抑藻作用 13

4.2 梭鱼草根茎提取物对铜绿微囊藻生长的影响 13

4.3 结论 14

5 致谢 15

6 参考文献 15

1 绪论

藻类水华的成因

蓝藻水华及其特征

社会发展带动着工业的发展,一方面推动着人类生活水平的提高,另一方面却造成了不经处理的工业污水、生活污水的大量排放。大量污水进入水体,造成了水体的富营养化,为藻类生长提供了适宜的环境,导致藻类大量繁殖,取代水体内高等植物成为所在生态系统内部的优势种群,使水体变色并产生严重异味。这种自然现象称为水华。

大部分的淡水藻类在适宜的水体环境下都可能形成水华,因此当今的藻类水华主要存在于淡水中。过多的藻类覆盖于水体上,与水体内其它水生动植物形成营养竞争的关系,减少了水体内部的氧气含量使其变为“死水”,对水体的生态系统以及景观效果造成了较大的危害,同时对人类的生活也造成了一定的影响。

藻类水华形成原因

水体富营养化之所以能造成水华大面积的爆发,原因在于各类污水与水体融合后,其中的无机元素譬如氮、磷等大量进入水体,导致水体内此类元素无机盐含量升高,为藻类的生长繁殖提供了必需的无机物质[1]

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