【作者】 刘妍娟；

【导师】 曾清如； 储昭升；

【作者基本信息】 湖南农业大学 ， 环境工程， 2009， 硕士

【摘要】 结合07年夏季洋河水库的氮、磷、生物量的监测数据,采用三角瓶实验对低、中、高磷浓度级别的不同氮磷比培养条件下的螺旋鱼腥藻的生长及异形胞形成进行了研究；采用10L玻璃瓶实验对螺旋鱼腥藻在富营养底泥条件下水华爆发时土嗅素(Geosmin)产生情况进行了研究,并用固相微萃取和气质联用对鱼腥藻藻细胞内和细胞外的土嗅素进行了测定；对2008年6-9月巢湖西半湖南淝河河口区域的常规水质进行检测,并利用气质联用-固相微萃取法检测水样的异味物质,考察了异味物质与叶绿素、TN、TP、DTP、CODCr、pH、DO、温度、透明度的关系。研究结果表明：1.三角瓶实验结果表明,在氮充足时,螺旋鱼腥藻不易形成固氮异形胞,消弱了异形胞的固氮能力；而在低氮营养条件下,螺旋鱼腥藻容易形成固氮异形胞,特别是当N=0.1mg／L和N=0.2mg/L时,异形胞出现的频率最大；且由于高氮条件容易抑制异形胞的生成,导致螺旋鱼腥藻生长减慢,最大生物量减小,螺旋鱼腥藻生长能力受到氮的抑制,且高氮条件容易抑制螺旋鱼腥藻生成土嗅素；理想实验条件下与洋河水库实际情况的结果不一致,可能与洋河水库现场采样的螺旋鱼腥藻藻体未出现异形胞有关,可能与洋河水库现场采样的螺旋鱼腥藻藻体未出现异形胞有关,反而氮充足的区域发生了螺旋鱼腥藻的繁殖爆发。2.富营养底泥培养条件下,随着螺旋鱼腥藻生物量增加,土嗅素产生量随之增大,其最大产生浓度可达626ng／L,远超出人体可感知浓度(10ng／L)；螺旋鱼腥藻细胞分泌土嗅素与叶绿素的速率并不完全相同,嗅味物质在螺旋鱼腥藻生物量达到最大值前76h左右达到最高浓度；生长过程中,土嗅素主要分布在螺旋鱼腥藻藻细胞内,占总含量的85%-95%,远高于胞外含量；本试验培养初期底泥刚向水体中释放氮时,藻细胞更倾向利用类异戊二烯合成土嗅素,导致土嗅素与叶绿素含量比增大.随着水体中的氮含量逐渐充足,藻细胞内的土嗅素与叶绿素含量比值趋于稳定,维持在0.0015左右。因此,当野外水体的氮含量充分时,螺旋鱼腥藻土嗅素产生量的变化可通过叶绿素含量的变化得到反映。3.检测出2008年6-9月巢湖西半湖南淝河河口区域β-环柠檬醛为主要的异味物质,其浓度范围为1.077047-494.7695ng·L-1,且7月达到最大,7月平均浓度为114.4887ng·L-1。其中又以add3、add4这两点为最大,达到其它点位的2-400倍左右；巢湖南淝河河口区域水华暴发期在7月,可能与微囊藻的夏季爆发有关,河口add3点的藻华最为严重,这是由气候地理分布及TN、TP等营养盐的时空分布综合决定的；建议水处理厂特别应在夏季和秋季时,注意采取一定的方法处理饮用水的嗅味物质,而且控制饮用水异味物质的关键,是限制藻生物量水平。更多还原

【Abstract】 Combined with the data of nitrogen, phosphorus, biocess of Yang-he reservoir on July, 2007, flask experiments were applied to investigate the relationship between heterocyst formation and growth of Anabaena sp. at three phosphorus solutions with different nitrogen/phosphorus ratio,10L pyrex bottle experiments were applied to investigate the geosmin production and distribution of Anabaena sp. under eutrophic condition. Algal cell and media extracts were analyzed individually by solid-phase microextraction(SPME) and capillary gas chromatography-mass spectrometry(GC-MS). Lake Chao-hu is one of the fifth fresh water lakes in china with a surface area of 800 km2 and a water content of 20 billion m3. With increasing regional development in surrounding area, Lake Chao-hu, has shown abvious eutrophication over the years. The quality of water which gathered from Lake Chao-hu was detected, and off-flavor compounds were analyzed by solid-phase microextraction(SPME) and capillary gas chromatography-mass spectrometry(GC-MS).The results showed that:1. The flask experiments proved that Anabaena sp., under the sufficient nitrogen environment, was not likely to format heterocyst which can fix nitrogen, while low nitrogen condition can make Anabaena sp. format heterocyst easily and lead to the bloom of Anabaena sp., especially in N=0.1mg/L and N=0.2mg/L conditions. The result of flask experiments was not consist with that of reservoir Yang-he, this possibility because Anabaena sp. of Yang-he in 2007 had no heterocyst, so the highest TN content easily led to high concentration of algae.2. The result proved that geosmin produced by Anabaena sp. increases with the increasing Anabaena sp. cells numbers and the highest concentration recorded was 626ng/L, which was significantly above the perceptive concentration of human which is about lOng/L. Geosmin production was not synchronous with cells growth, and the highest concentration of geosmin was observed 76 hours earlier before the biomass of Anabaena sp. cells reached the highest point. Geosmin was found to be enriched in cell matrix rather than in medium that about 85～95% of total geosmin was concentrated in cell. The mechanism of such phenomena was also studied. The mud began to release nitrogen since the beginning of culturing and lower nitrogen concentration would induce the synthesis of geosmin using the isoprenoid precursors rather than the demand of chlorophyll accumulation. When the nitrogen concentration was sufficient in medium, the geosmin concentration can be calculated by monitoring the chlorophyll concentration since the geosmin/chlorophyll ratio would reach a stable value at-0.0015.3. The result proved thatβ-Cyclocitral was the principal off-flavor compounds, and its concentration range started from 1.077047-494.7695ng·L-1. Most of theβ-Cyclocitral was detected in July, the average concentration of which is 114.4887 ng·L-1, especially site add3 and add4, the concentration of which was 2-400 times than other sites. July was the period of algae bloom in Lake Chao-hu, especially in site add3. This is determined by climate-geography distribution and time-space distribution of nutrition such as nitrogen and phosphorous. It is suggested that water plant should take some method to treat off-flavor compounds of drinking water in summer and autumn, and the key of controling off-flavor compounds of drinking water is to limit biocess of algae or to separate algae and origin water.更多还原