【作者】 王媛媛；

【导师】 郑有飞； 陈非洲；

【作者基本信息】 南京信息工程大学 ， 环境科学， 2008， 硕士

【摘要】 微囊藻（Microcystis spp.）是太湖夏季蓝藻水华的优势类群,磷是微囊藻生长的限制因子;而沉积物的内源释放对湖泊的富营养化具有显著的影响,因此,研究微囊藻水华与沉积物营养盐的消长作用,对于了解湖泊蓝藻水华暴发的机理具有非常重要的理论意义,同时也能为湖泊富营养化的控制提供理论参考。本文通过野外调查和室内模拟实验,研究了微囊藻细胞内总氮、总磷和氮磷比的时空变化;微囊藻分解对沉积物营养盐含量的影响以及细菌对微囊藻分解的影响;微囊藻和沉积物中营养盐含量的周年变化。（1）微囊藻群体中的总氮、总磷含量及氮磷比都与时间（地点）和群体粒径及两者的交互作用之间存在着显著的线性相关关系。在时间尺度上,微囊藻群体中总磷含量的变化与温度的升降成正比;氮磷比的变化与温度的升降呈负相关的关系;在空间尺度上,氮磷比的变化不显著。通过对微囊藻群体组成的分析可知粒径为150～200μm的微囊藻是水华中的主体。（2）通过添加底泥和革兰氏阴性菌抑制剂NaN₃对不同粒径微囊藻分解的影响实验表明:小颗粒微囊藻（＜25μm）分解的速度最快;添加底泥和NaN₃处理微囊藻的分解率高于添加底泥而无NaN₃的处理,说明存在于底泥中的革兰氏阳性菌对微囊藻的分解起重要的作用。添加NaN₃后水中总溶解磷含量会快速升高,说明微囊藻群体中的磷可能大部分积聚在革兰氏阴性菌中;在无底泥处理中,总溶解磷占总磷的比例为64%-82%。分解实验表明微囊藻分解—沉积物—细菌之间存在较为复杂的关系。（3）沉积物与微囊藻中氮磷含量的季节变化表明,沉积物中总氮和总磷含量与微囊藻中的氮磷含量呈现负相关关系。沉积物中总氮和总磷含量8月份最低,而微囊藻中总氮和总磷含量却是8月份最高。沉积物中氮磷比夏秋季最高,其它季节较低。本研究说明微囊藻水华暴发期间,微囊藻的分解和对营养盐的吸收对沉积物中的氮磷含量影响较大。更多还原

【Abstract】 Microcystis spp. is a dominant taxa during the cyanobacteria blooms in Lake Taihu. Phosphorus is limited factor to the growth of Microcystis, and nutrients released from the sediments have great influence on the eutrophication process of the lake. Our studies aimed to study the influence of Microcystis on the nutrient contents of the sediments, which would further help to understand the mechanism of cyanobacteria bloom and eutrophication control in the lake. Thus, through the field investigation and simulation experiment in the laboratory, we studied the temporal and spatial dynamics of total nitrogen and phosphorus in the colonies of Microcystis, relationship among Microcystis decomposition, the nutrients of the sediment and bacterial, temporal dynamics of the nutrient content in Microcystis and the sediment.（1） The contents of total nitrogen （TN） and total phosphorus （TP） in the colonies of Microcystis showed significantly linear relation with time （site）, the colonial size and their interactions. In the time scale, the TP content had positive relation with temperature, while TN/TP had negative relation with temperature. TN/TP showed no significant difference in the space scale.（2） We conducted simulation experiment in the laboratory to study the effect of the sediment and gram-negative bacterial inhibitor （NaN₃） on the different sizes of the colonial Microcystis. The highest decomposed rates were recorded for the smallest size Microcystis fraction （<25μm）. The decomposed rates were higher in the treatment with the sediment and NaN₃ than with the sediment and no NaN₃, which meant the important role of gram-positive bacterial in the Microcystis decomposition. The total dissolved phosphorus （TDP） increased sharply in the beginning of the experiment in the treatments with NaN₃, which means the most phosphorus accumulated in the gram-negative bacterial cells around the colony. The ratios of TDP concentration to initial TP concentration were 64%-82% in the no-sediment treatments. Our results suggest that both gram-negative and gram-positive bacteria play an important role in the decomposition of Microcystis cells and in the release of phosphorus from Microcystis colonies.（3） The field investigations on the nutrient contents in the sediments and Microcystis were made during 2006-2007. The contents of TN and TP in the sediments negatively related with the contents of TN and TP in Microcystis. The lowest contents of TN and TP in the sediment appeared in August when the highest values occurred in Microcystis. TN/TP in the sediments showed higher values in summer and autumn than in other seasons. Our results suggested that the contents of TN and TP in the sediment were affected by the decomposition and nutrient assimilation of Microcystis.更多还原