【作者】 王书航；

【导师】 孙世群； 姜霞；

【作者基本信息】 合肥工业大学 ， 环境科学， 2010， 硕士

【摘要】 为识别巢湖藻类水华暴发的主要影响因素,采用为期一年的现场采样及野外模拟实验相结合的方法,研究了2008水华暴发现状及优势种的变化;采用多元统计方法对入湖河流进行了聚类和污染等级分级,并判别了藻类生物量与河流营养盐输入负荷的关系;分析了各水环境因子对藻类生物量的影响,并筛选出对对藻类生物量相对重要的因子;估算了水-沉积物界面氨氮的扩散通量,并利用氮形态的连续分级提取法研究了沉积物氮形态的季节性变化,并探讨了不同季节对有效氮形态起主要作用的氮形态;通过现场观测及围隔模拟试验,定量研究了水华暴发的整个过程,同时观测了风浪对巢湖水华藻类水平迁移和垂直混合的影响。研究结果表明:（1）蓝藻在巢湖水华藻类中常年占优势,但优势种群有所差别,春季鱼腥藻占优势,微囊藻次之;夏、秋两季微囊藻占绝对优势.表层沉积物中藻类生物量从1月到夏初呈下降趋势,最小值出现在6～7月份之间,然后逐渐升高,最大值出现在冬季.温度是巢湖藻类生物量变化最为显著的影响因子。（2）入湖河流可分为三类,为城市污染河流、清水产流河流和水质保持河流,其中城市污染河流输入到巢湖中CODMn、NH₄⁺-N、TN、TP量分别占全部入湖河流污染负荷的41.29%、89.49%、72.27%和60.14%;因子分析显示有机污染是入湖河流主要污染来源,九条环湖河流污染分级排序为:南淝河>十五里河>派河>双桥河>柘皋河>裕溪河>白石山河>兆河>杭埠河;入湖区藻类生物量与入湖河流NH₄⁺-N、TN、TP的输入量呈正相关,但TN的输入量更能显著增加藻类生物量。（3）巢湖水环境自西向东分为重度污染区、中度污染区和轻度污染区,Chla、DTN可作为巢湖水环境空间显著性差异的指示因子。各监测点污染分级排序为:南淝河入湖区>十五里河入湖区>塘西河入湖区>西半湖湖心>派河入湖区>杭埠河入湖区>忠庙>兆河入湖区>坝口>东半湖湖心>造船厂>中垾乡；水环境质量月平均污染分级排序为:8月>6月>9月>4月>5月>7月>10月>1月>3月>12月>11月>2月。不同季节筛选出对藻类生物量相对重要的环境因子不同,全年总磷、总氮、温度、硝氮、氨氮与藻类生物量较为密切。（4）上覆水中NH₄⁺-N含量随水华暴发强度的增加而减小,溶解性总氮（DTN）含量在水华暴发后明显升高,而NO₃^--N含量只在水华暴发严重时才明显减少.上覆水中DTN的主要组成部分在大规模水华暴发前（4月～5月）是NO₃^--N和NH₄⁺-N,在水华暴发后则是DON.间隙水中以NH₄⁺-N为主,其浓度随温度的增加而升高;DON呈先下降后上升的趋势.通量计算结果表明,沉积物作为NH₄⁺-N的“源”一直由间隙水向上覆水释放,西半湖扩散通量在13.06 mg/（m²·d）～32.94 mg/（m²·d）之间,东半湖扩散通量在4.54 mg/（m²·d）～17.41 mg/（m²·d）之间.（5） FN、EN呈夏季低而秋、冬季节高的分布趋势;HN在冬季含量较高,而春、夏季节含量较低;RN含量的季节性变化不明显;TN含量在夏较低而秋、季节较高;MN含量的季节性变化顺序为冬季>春季>秋季>夏季.不同季节对有效氮起主要作用的氮形态不同,春季为酸解氨基酸态氮（AAN）,夏季、秋季为可交换态氮（EN） ,冬季为游离态氮（FN）.（6）充足的营养来源是藻类异常增殖的关键,沉积物作为水华暴发营养物质的内源和“种源”,为浮游藻类的生长提供必要的营养和“种子”;风浪的扰动加速了藻类的增殖以及藻类在水-沉积物界面的交换量;在风速小于3 m·s-1时,团状水华在水面漂移速度与风速呈指数相关性,相关性系数为0.91,当风速大于3 m·s-1时,藻类上下混合沉入水中;主导风向决定了水华的分布状况,试验期间,同一采样点,当其处于下风向时,湖水表层生物量是处于上风向时的8.8倍。更多还原

【Abstract】 In order to identify the main factors that influencing of alga blooming in Chaohu Lake,Situ observation and constructed enclosure simulation experiment were conducted for one year.Algae distribution in Chaohu Lake and Variation of dominant species was investigated.the inflow rivers are clustered and the pollution levels are classified by statistical methods and the correlation between algal biomass and the river nutrients input loads are derived.Inorganic nitrogen fluxes at water-sediment interface was analyzed, seasonal occurrence characteristics of the free nitrogen , the exchangeable nitrogen , the acid hydrolysable nitrogen and the residual nitrogen in the surface sediment of Chaohu Lake were studied by sequential extraction methods. Quantitative research on alga blooming process was conducted and horizontal transference and vertical hybrid effects of blooming alga caused by wind waves in Chaohu Lake were also observed.The results indicates that:（1） cyanobacteria algae dominated in bloom algae all the year round in Chaohu Lake, but different dominant species appeared in different seasons. Anabaena dominanted in spring with microcystis as subdominant specie; Microcystis dominated through the whole summer and autumn. The algae biomass in surface sediments had a tendency to gradually decrease from January to early summer, and minimum appeared between June and July ,while it increased through mid-summer and autumn, maximum appeared in winter. Multiple stepwise regression showed that temperature was the most significant factor which impacted the variation of algae biomass in Chaohu Lake.（2） the inflow rivers could be classified into three types, namely urban pollution rivers, clear aquatic flow rivers, and water quality stable rivers. The input load of CODMn、NH₄⁺-N、TN、TP from urban pollution rivers to the whole lake are 41.29%、89.49%、72.27% and 60.14% to all inflow rivers Respectively. Organic pollution is the main pollution resource of inflow rivers by factor analysis. The pollution rank of nine inflow rivers are as follows: Nanfei river>Shiwuli river>Paihe river>Shuangqiao river>Zhegao river>Yuxi river>Baishishan river>Zhaohe river>Hangbu river. The algal biomass and the NH₄⁺-N, TN, TP inputs of inflow rivers are positively correlated, while the TN inputs could increase the algal biomass more significantly.（3） Chaohu Lake could be divided into severe polluted area, moderately polluted area, and mildly polluted area from the west to the east. The Chla and DTN are the directive factors for the significantly spatial differentiation of water environment. The pollution classification sequence of monitoring sites was Nanfei river inlake area> Shiwuli river inlake area> Tangxi river inlake area> West lake center area> Paihe river inlake area> Hangbu river inlake area> Zhongmiao area> Zhaohe river inlake area> East lake center area> Ship factory> Zhonghan town area. The classification sequence of monthly average water environment quality was August> June> September > April> May> July> October> January> March> December> November> February. The screened relatively important environmental factors to algal biomass vary with seasons. The TP, TN, temperature, NO₃^--N and NH₄⁺-N are closely related to algal biomass all the year round.（4） NH₄⁺-N decreased as the algal bloom intensity increased, while dissolved total nitrogen increased apparently after algal bloom, NO₃^--N decreased only during serious algal bloom period in overlying water. NO₃^--N and NH₄⁺-N were the main part of nitrogen before algal bloom （in April and May） and then DON was the main part after that. In pore water, NH₄⁺-N was the main part of nitrogen which increased as temperature rised. Dissolved organic nitrogen decreased first and then increased. Fluxes calculation results suggested that the sediment was the source of NH₄⁺-N which dissolved from pore water to overlying water, NH₄⁺-N fluxes were ranged from 13.06 mg/（m2·d）～32.94 mg/（m2·d） in west semi lake, and were ranged from 13.06 mg/（m2·d）～32.94 mg/（m2·d）in east semi lake; The sediment was the pool of NO₃^- -N before algal bloom period, but was the source of NO₃^--N which increased nitrate concentrations in overlying water after that.（5） The concentrations of FN and EN was lower in summer and higher in autumn and winter; HN had a higher level in the winter and a lower level in spring and summer; While RN varied little; The TN concentrations had a lower level in summer and higher level in autumn and winter; the seasonal order of mineralizable nitrogen （MN） content was winter> spring> autumn> summer. The nitrogen forms playing a major role on available nitrogen had a disparity in difference seasons, which was the amino acid nitrogen （AAN） in spring, EN in summer and autumn, FN in winter.（6） sufficient nutrient sources played a crucial role in algal blooming process. Sediment supplied nutrients and seeds for this process as the resource of nutrients and algae seeds. Hybrid caused by wind waves accelerated alga multiplication and alga sedimentation and suspension on water-sediment interface. When wind speed was less than 3m·s-1alga clusters drifted on water surface with speed which was exponential dependent on wind velocity with dependent coefficient equaling 0.9052. When wind speed was larger than 3m·s-1, alga mixed up-down together and sunk into lake water. Leading wind directions dominate the distributions of alga blooms. During the test period alga biomass on surface water in leeward wind is 8.8 times as that on upper drift.更多还原