三种藻胞外氨基酸释放及其对水体DON的贡献

发布时间：2018-07-15 12:08

【摘要】：近年来,随着人类工农业生产与各种生物活动加剧,营养物质在湖泊中不断富集,水体富营养化程度加剧,造成藻类大量繁殖,水华频繁爆发。水体中氨基酸及溶解有机氮(DON)是生物地球化学循环及生命过程的重要环节,是水体中重要的生物可利用性营养物质,对藻类生长繁殖及分布具有重要意义。藻类胞外有机物(EOM)作为水体氨基酸及DON的重要内源,开展对EOM中氨基酸及DON含量及组成的研究,对理清湖泊富营养化发生机理意义重大。本文通过对比藻生长过程中DON与氨基酸的类型与组成,探讨了不同藻类间及藻类在水体中氨基酸的释放规律及其对有机氮的贡献。选取3种典型淡水藻铜绿微囊藻(Microcystis aeruginosa)、四尾栅藻(Scenedesmus quadricauda)及喙头舟形藻(Navicula rhynchocephala)作为室内培养研究对象,并结合典型藻型湖泊滇池,进行培养实验与实际水体的对比分析。采用三维荧光光谱-平行因子分析法(EEMs-PARAFAC)、柱前衍生高效液相色谱(HPLC)分析3种藻在生长时期及水华爆发与消亡时期,DON特征与胞外游离氨基酸(DFAA)、结合氨基酸(DCAA)的含量组成等差异,并对藻源氨基酸对DON的贡献问题进行了探讨。对培养实验研究发现,藻在生长过程中有机质被大量释放,且不断将无机氮转化为DON释放到水体,DON逐渐变为主要氮形态。藻类生长指数期及稳定期会产生对TDN的大量吸收利用,在湖泊中藻类生长过程中对水体有一定的脱氮作用,但在藻类衰亡过程中,藻类氮释放量增加,水体氮含量会大量增加。EEM-PARAFAC对藻生长时期EOM分析得出类色氨酸(C1)、类腐殖质(C2)、类蛋白质(C3)及类酪氨酸(C4)4种组分,类色氨酸、类酪氨酸与类腐殖质3组分含量均随生长过程不断增加,且类色氨酸与类酪氨酸荧光组分在总荧光强度中占比不断增加。培养实验中DFAA与DCAA在藻生长期均呈不断累积趋势,且在衰亡期初期均大量释放,与荧光结果分析相同;铜绿微囊藻在生长期代谢的DON、DFAA与DCAA含量及其对DON贡献率均最高,在衰亡期会吸收DFAA维持生长,且在衰亡后NH4+及DCAA为主要氮形态,这可能是蓝藻水华持续时间长,治理难度高的重要原因。对滇池水华爆发期及消亡期研究发现,藻向水体释放了大量氮营养物质,TDN、NH4+及DON浓度分别增加了2.65 mg/L、1.21 mg/L及0.82 mg/L,有机质在水华消亡期也有大量的释放,与培养实验结果相同。通过EEM-PARAFAC模型识别出滇池样品中4个荧光组分,类色氨酸(C1’)、陆源类腐殖质(C2’)、类酪氨酸(C3’)、陆源类腐殖质(C4’)。类色氨酸及类酪氨酸组分与培养实验识别出相同,且类色氨酸(C1’)与类酪氨酸(C3’)在藻消亡期释放量均有明显增加,与培养实验结果相同。水华消亡过程中,DFAA增加了7.99μmol/L,DCAA增加了19.9μmol/L,对水体氨基酸的代谢量较大,藻类代谢是藻型湖泊氨基酸的主要来源。水体氨基酸单体中甘氨酸、精氨酸及丙氨酸浓度均较高,与室内培养实验得到的结果相似。DFAA对水体DON贡献率为4.7~26.2%,DFAA对水体DON贡献率为14.2~43.6%,THAA对水体DON的贡献率为14.7~69.5%。因此表明,蓝藻等藻类生长及衰亡是湖泊有机氮的重要来源,其产生的藻源型有机氮物质及氨基酸是湖泊DON的重要内源,为湖泊水华爆发提供了营养条件。因此,解决湖泊富营养化问题仅靠切断外源有机氮物质的输入可能难以取得较好效果。
[Abstract]:In recent years, with the intensification of human industrial and agricultural production and various biological activities, nutrients are enriched in lakes and the degree of eutrophication is aggravated, resulting in a large number of algae reproduction and frequent eruptions of water bloom. The amino acids and dissolved organic nitrogen (DON) in water bodies are important links in biological geochemical cycle and life process, and are important in water bodies. Bioavailability of nutrients is of great significance to the growth, reproduction and distribution of algae. As an important endogenous source of amino acids and DON in water, the study on the content and composition of amino acids and DON in EOM by algae (EOM) is of great significance to clarify the mechanism of eutrophication in lakes. This paper compares DON with DON in the growth process of algae. Type and composition of amino acids, the release of amino acids in different algae and algae and their contribution to organic nitrogen were discussed. 3 typical freshwater algae (Microcystis aeruginosa), four Scenedesmus quadricauda (Scenedesmus quadricauda) and scaphoid scaphoid (Navicula rhynchocephala) were selected as indoor culture research. Images, combined with the typical algae Lake Dianchi, were compared with the actual water body. The three dimensional fluorescence spectrum parallel factor analysis (EEMs-PARAFAC) and pre column Derivatization High Performance Liquid Chromatography (HPLC) were used to analyze the growth period and the eruption and extinction period of 3 kinds of algae, the characteristics of DON and the extracellular free amino acids (DFAA), and the amino acids (the amino acids). The difference in the composition of the content of DCAA) and the contribution of the algae source amino acids to the DON were discussed. In the culture experiment, it was found that the organic matter was released in a large amount during the growth process, and the inorganic nitrogen was converted to DON to the water body, and the DON gradually became the main nitrogen form. The growth index period and the stable period of the algae would produce a large amount of TDN. Absorption and utilization of algae in the algae growth process has a certain denitrification effect on the water body, but in the process of algae decay, the release of nitrogen in algae increases and the nitrogen content in water will increase by.EEM-PARAFAC, 4 components of tryptophan (C2), class of humus (C2), protein like (C3) and tyrosine (C4), and tryptophan The 3 components of acid, tyrosine and humus like compounds increased with the growth process, and the proportion of tryptophan and tyrosine like fluorescent components increased continuously in the total fluorescence intensity. In the culture experiment, DFAA and DCAA were all accumulated in the growth period of the algae, and were released in the early decay period. The contents of DON, DFAA and DCAA and their contribution to DON during the growth period were the highest. In the decay period, the growth of DFAA was maintained, and after the decay, NH4+ and DCAA were the main nitrogen forms. This may be an important reason for the long duration of cyanobacteria bloom and the high difficulty of treatment. The study of the outbreak and extinction period of Dianchi water bloom found that algae release to the water body. The concentration of TDN, NH4+ and DON increased by 2.65 mg/L, 1.21 mg/L and 0.82 mg/L respectively. The organic matter was also released in a large amount in the extinction period of water bloom, which was the same as that in the culture experiment. By the EEM-PARAFAC model, 4 components of the Dianchi sample, tryptophan (C1 '), terrigenous humus (C2'), and tyrosine (C3) were identified. "), terrigenous humus (C4"). Tryptophan and tyrosine like components are the same as that in culture, and the release of tryptophan (C1 ") and tyrosine like (C3 ') in the extinction period of algae is obviously increased, which is the same as that in the culture experiment. In the process of extinction, DFAA increased by 7.99 mu mol/L, DCAA increased by 19.9 mu mol/L, and the amino group was amino. The metabolic amount of acid is large. Algae metabolism is the main source of amino acid in algae type lakes. The concentration of glycine, arginine and alanine in the amino acid monomer of water body is higher. The contribution rate of.DFAA to water body DON is 4.7~26.2%, DFAA to DON of water body is 14.2~43.6%, and the contribution rate of THAA to water DON is 14.. 7~69.5%. therefore indicates that the growth and decay of cyanobacteria and other algae are important sources of organic nitrogen in lakes. The algae source organic nitrogen substances and amino acids produced by algae are important endogenous sources of Lake DON, and provide nutritional conditions for the outbreak of Lake bloom. Therefore, it may be difficult to solve the problem of eutrophication in lakes only by cutting off the input of exogenous organic nitrogen. Good results.
【学位授予单位】：南昌大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X524

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