北京城市湖泊沉积物中微生物磷脂的分布特征

以北京市城市湖泊八一湖柱状沉积物为研究对象,通过Bligh和Dyer萃取方法,萃取4个采样点柱状沉积物每2 cm分层中的磷脂,使用水质总磷的钼酸铵分光光度法（GB 11893-89）测定分层中磷脂浓度,按照Findlay给出的转换因子（1 nmol磷相当于3.4×107个微生物细胞）,估算出各样点平均微生物含量及分层的微生物量含量。现场测定水体中的pH值、DO、叶绿素等指标,表明八一湖整体水质状况良好。结果表明：八一湖4个采样点磷脂的平均含量分别为1.581μg/gdw,6.741μg/gdw,0.696μg/gdw,2.143μg/gdw。水平分布上,位于湖泊中心的2号采样点磷脂平均含量远高于其他三个采样点的磷脂含量。湖中心水流速缓慢,水流基本没有流动,大量的外源营养物质不能够及时扩散,大部分都会沉淀下来。在垂直分布上,各采样点磷脂含量均随沉积物深度的增加而降低。表层（0 cm～4 cm）磷脂含量的下降趋势相似,均呈现出2 cm分层磷脂含量为4 cm分层磷脂含量的2～3倍;而（4 cm～10 cm）各采样点磷脂含量的下降趋势各不相同。根据Findlay给出的转换因子,沉积物中微生物的含量变化趋势和磷脂含量一致表层（0～6 cm）沉积物微生物含量高,微生物活动活跃,深层（6 cm～10 cm）微生物含量低,微生物活动缓慢。

The Vertical Distribution of Sedimentary Microbial Biomass on Urban Lake in BeiJing

Sediment samples for phospholipids analysis were collected from four sites in Beijing Ba Yi Lake.By Bligh and Dyer extraction method extracted the phospholipids of four sampling spots in the Layer of each sediment core.By ammonium molybdate spectrophotometric method(GB11893-89)methods measured the phospholipids in sediments of four sampling sites.According to Conversion factor given by Findlay(1nmol P is equivalent to 3.4×107 microbiological cells),the average microbial biomass of various sites were estimated.pH value,DO,Chlorophyll and other indicators of water determinate by at spot show that the overall water quality of Beijing Ba Yi Lake is consistent.The results show that the phospholipids content of four samples range from 1.581 μg/gdw,6.741 μg/gdw,0.696 μg/gdw,2.143 μg/gdw.Because of the center of the Lake water flow slowly,the nutrients can’t be spread in time,Most of the nutrients will settle down,Regarding to the vertical distribution of sediment in the Lake center,phospholipids content of sample at No.2 sites higher than the other three sites.Microorganisms increased with the decrease of sediment depth in all sampling sites.In the surface(0 cm~4 cm) phospholipids contents in the downward trend is similar,both showed 2 cm Layered phospholipids contents in 4 cm Layered phospholipids contents in 2 ~ 3 times;And(4 cm~10 cm) all sampling points phospholipids contents in the downward trend each are not identical.According to the Findlay conversion factors,the content of the microorganism in trends and phospholipids contents is agreement Ba Yi Lake sediment microbial surface 0~6 cm high content of active microbial activity,microbial content of 6 ~ 10 cm deep low,microbial activity slowly.