【作者】 王敏；

【导师】 张智；

【作者基本信息】 重庆大学 ， 城市环境与生态工程， 2009， 硕士

【摘要】 水体富营养化是当今人类面临的重大环境问题之一。三峡工程是一项集防洪、发电、航运综合效益于一体的大型水利枢纽工程,三峡库区水环境安全对库区和长江中下游的社会经济发展有着十分重要的意义。嘉陵江是三峡库区最大支流,是重庆城区的重要饮用水源,其出口段局部水域水质下降,近些年小环藻水华时有发生,随着三峡水库的运行,水流减缓,营养盐稀释减弱,藻类的活动空间和发生程度有加大的趋势。基于国内外湖、库的蓝藻水华研究多,而对江、河硅藻水华研究滞后的状况,小环藻水华不仅表明嘉陵江出口段水质降低,同时也给三峡库区水污染控制提出了新的要求。为了研究嘉陵江出口段小环藻“水华”发生规律及其生物学毒性,2007年1月~2008年3月对朝天门、化龙桥、磁器口的相关水体开展了现场调研和室内测试,通过环境因子与藻类相关性分析找出它们之间的关系,同时培养“水华”小环藻进行毒性实验。主要研究结果如下:①嘉陵江出口段早春发生水华藻类属硅藻门(Bacillariophyta),中心纲(Centricae),圆筛藻目(Coscinodiscales),圆筛藻科(Coscinodiscaceae),小环藻属(Cyclotella)的星肋小环藻(Cyclotella asterocoststs)。②小环藻水华是呈年周期性暴发。小环藻每年早春(1月下旬~3月上旬)发生,数量峰值明显,水华期间小环藻占总藻密度的60%~80%。③经SPSS16.0软件各理化指标与小环藻的分析比对可知,小环藻水华是各理化因素共同作用的结果,即在较缓的流速(0.05-0.20m?s-1)、充足的营养盐(TN:2.17-2.24mg?L-1,TP:0.07-0.14mg?L-1)、足够的光照(11.24h)等前提条件存在的情况下,加上较低的水温(8-11℃)才有可能发生“水华”。较短的生活世代(2-3d)使其在适宜环境中迅速增殖并在短期内成为优势藻种。在一定条件下,水温是小环藻发生水华的主导因子。④小环藻硅壳破碎效果是毒性实验的保证,直接关系到饮用水源的安全性。通过研磨法、反复冻融法、超声波破碎法三种破壁试验结果分析比较,超声波破碎法是小环藻的最佳破壁方法,通过正交试验选取频率22Khz、功率400W、超声波总作用时间20min、单次超声时间为15s、时间间隔5s为小环藻破壁试验的最优参数组合。⑤从异常毒性检测结果可以看出,注射经破碎后小环藻藻液的小白鼠在观察期间(48小时)进食、活动均正常,生长状况良好,无中毒症状及死亡,小环藻的异常毒性检测结果符合国家药典2005版的要求,实验认为小环藻属无生物毒性藻类。更多还原

【Abstract】 Water eutrophication is one of the important environmental problems which human beings face. The three gorges project is a large-scale water conservancy project which integrates various functions including flood control, generate electricity and ship. Thus, the water environment security of this artificial reservoir has very important significance in improving social economic development of the reservoir area and middle and lower of Yangtze River. The Jialing River is the biggest anabranch in Three Gorges Reservoir (TGR); also, it is one of the most important drinking water resources of Chongqing. Water quality condition of local water body of outlet section of the Jialing River had become deterioration. Water bloom which was mainly caused by Cyclotella had broken out frequently during recent years. With the operation of TGR, the flow velocity slowed down, nutrient dilution effect was weakened. As a result, both algous activity space and occurrence degree had an increasing trend. The study on Cyanobacteria bloom which broke out following a regular basis in lake or reservoir was common at home and abroad, but the study on diatom bloom which broke out in river basin was obviously lag. This phenomenon not only foreshowed water quality deterioration of outlet section of the Jialing River, but also put forward strict demand for water pollution control of TGR.In order to study the occurrence regularity and biological toxicity of Cyclotella bloom which broke out in outlet section of the Jialing River, field investigation and indoor test were carried out aimed at related water of ChaoTianMen, HuaLongQiao and CiQiKou from January 2007 to March 2008.Used correlation analysis to find out the relation between these environmental factors and algae, then, cultivated Cyclotella which caused diatom bloom for toxicity test. The principal conclusions of this paper were obtained as follows.①The appraisal result showed that the Cyclotella asterocoststs which belongs to Bacillariophyta, Centricae, Coscinodiscales, Coscinodiscaceae, Cyclotella was the dominant algae which caused the water bloom in outlet section of the JiaLing River in early spring.②The occurrence time of Cyclotella bloom showed a clear yearly periodicity regularity. The rapid proliferation of Cyclotella would cause water bloom in outlet section of the Jialing River in early spring (from January to March) each year and its amount had a statistically evident peak value. The proportion of Cyclotella density to total algae density reached to 60%~80%.③Physical and chemical indexes and the amount of Cyclotella were treated and statistically analyzed with SPSS16.0 software. Statistical analysis showed that Cyclotella bloom is result from the interaction of physical and chemical factors. That is to say, it might occur under these preconditions including lower velocity of flow (0.05-0.20 m/s), adequate nutrients (total nitrogen concentration is 2.17-2.24 mg/L and total phosphorus concentration is 0.7-0.14 mg/L), enough illumination time (11.24 hours), lower water temperature (8-11℃), and so on. A short generation time (between two and three days) could made itself proliferated rapidly in suitable living environment and then became the dominant algae species in outlet section of the JiaLing River in short order. It could be concluded that maybe water temperature was the dominant factor for the occurrence of Cyclotella bloom under certain conditions.④The crushing effect of silica shell of Cyclotella was the guarantee of toxicity test and it had a close bearing on the quality monitoring of drinking water. Ultrasonic cell-break was considered to the best crushing method for Cyclotella in terms of analyzing and comparing the crushing effect of grinding method, freeze-thaw method and ultrasonication. The result of orthogonal test showed that the frequency, power, total action time of ultrasonic, unit of action time and time interval of ultrasonic cell-break method under the optimum condition were 22 kilohertz, 200 wattages, 20 minutes, 15 seconds, 5 seconds, respectively.⑤The result of toxicity test showed that the food intake, vital movement and growth status of white mice were in order in the observation time (48 hours) after injected with cytolymph of Cyclotella, and there were no poisoning symptom or death phenomenon. This result could meet the requirement of State Pharmacopoeia (2005 edition). Therefore, it was considered that the Cyclotella which caused water bloom in outlet of the Jailing River does not have biological toxicity.更多还原