【作者】 吴雪峰；

【导师】 李小平；

【作者基本信息】 东华大学 ， 环境工程， 2010， 硕士

【摘要】 湖泊富营养化及随之暴发的藻类水华成为中国以及世界许多国家面临的重大环境问题,尤其是作为城市饮用水水源的湖泊富营养化问题更是对城市供水的安全构成严重威胁。本文以上海市淀山湖为研究对象,以保障上海市安全供水为目标,在分析了淀山湖历史（1986-2007年）营养物水平和当前水质现状（2008-2009年）的基础上,系统的研究了淀山湖浮游植物增长营养物限制情况及其与营养盐之间的关系。（1）通过分析淀山湖22年（1986-2007）间水质监测数据表明淀山湖生态系统发生了重大变化,湖泊富营养化水平也从贫营养化转变成重度富营养化状态。TN、TP和COD等指标含量持续增加,直接导致溶解氧下降、透明度降低和湖泊富营养化;淀山湖浮游植物优势种类由中营养型藻类逐步向富营养型藻类转变,硅藻在浮游植物中比例逐年减少,而绿藻和蓝藻优势种的比例逐年增加,造成浮游植物种类数呈下降趋势,生物多样性锐减;（2）通过实验室藻类增长的生物学评价（Nutrient EnrichmentBioassay）试验研究淀山湖浮游植物增长营养物限制表明10-12月份添加PO₄^3--p能提高相对比较系数,增加浮游植物的现存量和增长率,而添加NO₃^--N和NH₃-N对相对比较系数、浮游植物的现存量和增长率影响不大,添加磷+硝氮能够显著增加生物量,但从主效应分析看磷与硝氮之间不存在交互作用,仅是磷促进浮游植物生长,10-12月磷是限制浮游植物增长的限制性因子;在2-3月间由于淀山湖水体中有充足的氮磷（总磷0.3mg/L,总氮7mg/L）,湖体能提供足够的营养盐供浮游植物生长,再增加营养盐对浮游植物的生长影响不大,在这期间营养物不是限制浮游植物生长主要因素。（3）现场藻类增长的生物学评价试验表明在4-6月份添加PO₄^3--p能提高相对比较系数,增加浮游植物的现存量和增长率,而添加NO₃^--N和NH₃-N对相对比较系数、浮游植物的现存量和增长率影响不大,说明在4-6月份磷对浮游植物生长有明显促进作用,磷是限制浮游植物增长的限制性因子;在7-9月份添加磷对浮游植物的生长影响不大,而添加氮（氨氮和硝氮）能提高相对比较系数和增加浮游植物的现存量,淀山湖浮游植物生长的限制性因子已经由4-6月份的磷限制转变成7-9月份氮（NO₃^--N和NH₃-N）限制。因此,淀山湖浮游植物增长营养物限制全年经历了磷限制（10月-12月）到不受营养物限制（2月-3月）再到磷限制（4月-6月）最后转为氮限制（7月-9月）这么一过程。（4）分析2008-2009年水质监测数据和生态数据得出:TP出现两个峰值分别为10-3月份和5-7月份,TN出现两个峰值分别为1-3月份和6-7月份,而叶绿素-a的两个峰值在3-5月和6-7月,营养盐与叶绿素-a呈错开分布,且可被浮游植物直接利用的氨氮+硝氮在总营养盐中的比例变化非常大,相比之下采用氨氮+硝氮/磷酸盐比TN/TP更好的判断浮游植物增长营养物限制,当（氨氮+硝氮）/磷酸盐≤57时,淀山湖浮游植物增长属于氮限制;当57＞（氨氮+硝氮）/磷酸盐＜71时,氮磷对浮游植物增长都不具有显著性;当（氨氮+硝氮）/磷酸盐≥71时,淀山湖浮游植物增长属于磷限制。更多还原

【Abstract】 Lake eutrophication and the outbreak of algal bloom subsequently become major environmentalissues facing in China and over the world. In particular, as the urban drinking water resource, thelake eutrophication exerts a serious threat on the security of the water supply. This paper, in order toprotect the safety of water supply in Shanghai, taking the Dianshan Lake as the research object, carryout the study about the nutrient limiting factors of the phytoplankton growth and its relationship withthe nutrients, based on the nutrient levels over the history （year 1986-2007） and the current status ofwater quality （2008-2009）.（1） By analyzing the water quality data during the past 22 years （1986-2002）, the ecosystem ofLianshan Lake have undertaken great changes, with the water eutrophication level from poor tosevere. The water parameters such as TN, TP and COD experience continuous increase, with DOand transparency decrease as a result. The dominant species of phytoplankton transform gradually tonutrient-rich, the proportion of diatom gradually decrease while the green and blue algal increasewhich leads the species of phytoplankton and the diversity decrease sharply.（2） The Nutrient Enrichment Bioassay in Laboratory is conducted to study the nutrientsrestriction of phytoplankton growth. The result shows that the enrichment of PO₄^3--P during Oct-Deccan increase the relatively coefficient, phytoplankton biomass and growth rates, while theenrichment of NO₃ - N and NH₃-N have little impact. But the addition of P and NO₃-N can increasethe biomass significantly. However, the main effect analysis shows that there is no interactionbetween P and NO₃-N, with the P promote the growth of phytoplankton only, P is the limiting factorduring Oct-Dec. In Feb-Mar, for the sufficient N and P content in the lake which has no significanteffect on the growth of phytoplankton, nutrient is not a major factor during this period.（3） Nutrient Enrichment Bioassay on site is conducted to show that the enrichment of PO₄^3--Pduring April-June can increase the relatively coefficient, phytoplankton biomass and growth rates,while the enrichment of NO₃ - N and NH₃-N have little impact. It indicates that P promote the growth of phytoplankton during April-June which is the limited factor for the growth ofphytoplankton; However, during July-Sep, the addition of P has little impact on the growth ofphytoplankton, while the addition of NO₃ - N and NH3-N can increase the relatively coefficient andphytoplankton biomass that is the limited factor for the growth of phytoplankton this period. Thelimiting factor of phytoplankton growth experiences a changing all over the year, from P-limitation（Oct-Dec） to no limitation （Feb-March） then N-limitation （July-Sep）.（4） The analysis of the water quality data and ecological data during 2008-2009 is conducted toshow that: TP has two peaks in Oct-March and May-July, respectively; while the peaks of TN inJan-March and June-July, respectively and the Chlorophyll-a have two peaks in March-May andJune-July, respectively. The distribution of nutrients and chlorophyll-a is staggered, and theproportion of dissolved nutrients in the total nutrients change greatly, so the （NH₃-N+NO₃^--N）/PO₄^3--P can be a better parameter used to judge the nutrients limited status compared to TN/TP.When （NH₃-N+NO₃^--N） /PO₄^3--P≤57, the growth of phytoplankton can be limited by N; while the57≥（NH₃-N+NO₃^--N） /PO₄^3--P≤71, the growth of phytoplankton is not limited by either N or P;while （NH₃-N+NO₃^--N） /PO_<sup>3--P≤71, the growth of phytoplankton can be limited by P.更多还原