中文摘要：

湖泊水华存在复杂的生消过程，然而目前较多研究聚焦在水华持续阶段对湖泊生态系统的影响，却较少关注水华生消过程对湖泊水体和沉积物理化性质的影响．以巢湖为对象，根据历史资料确定水华区和非水华区，在相同位点分别于水华形成前期、形成期、持续期和消亡期采集水体和沉积物样品，分析水华生消过程对湖泊水体和沉积物理化指标及营养盐的影响．结果表明，巢湖研究区域水华形成期为5月中旬至6月中旬，持续期为6月中旬至9月上旬，之后进入水华消亡期．水体透明度、pH值和溶解氧在水华区与非水华区大部分时间存在显著差异，且随水华生消过程呈现不同的变化趋势，但水温、氧化还原电位和电导率在水华区和非水华区无显著差异，并随水华生消过程呈现相同的变化趋势．非水华区水体和沉积物中各形态氮、磷浓度明显低于水华区，且随时间变化幅度相对较小．在水华区，水体氮、磷浓度（总溶解性氮、硝态氮、氨氮、总氮、总溶解性磷、磷酸盐）在水华形成期和水华持续前期呈下降趋势，但在水华持续后期和水华消亡期呈增加趋势；沉积物氮、磷浓度（总氮、总磷）和总有机质含量显著高于非水华区，三者在水华区和非水华区随水华生消过程呈现不同的变化趋势．研究表明，水华生消过程对湖泊营养盐和水体及沉积物性质有不同的影响，这对湖泊富营养化治理和水华防治具有重要意义．

英文摘要：

Algal bloom （AB） is a complex process of algal formation, outbreak and extinction in lakes. Many previous studies have focused on impacts of AB outbreak on aquatic eco-environment, but limited attention has been paid to the effects of AB forma- tion, outbreak, and extinction on physieo-chemical properties of water and sediment in lakes. In this study, the AB and the free algal bloom （FAB） regions were determined in Lake Chaohu on the basis of previous reports and monitoring data. Water and sedi- ment samples were taken by sequential mode from May to September in 2012 to investigate effects of AB formation, outbreak and extinction an physico-chemical properties of water and sediment as well as nitrogen and phosphorous concentrations in sediment. Results showed that AB formation process occurred from May 15 to June 20 in Lake Chaohu, outbreak process lasted from June 20 to September 5, and then extinction process started. In most eases, water transparency （ SD）, water pH and water dissolved oxy- gen （DO） showed significant differences between the AB and FAB regions and presented different change trends with sampling time respectively. However, water temperature, oxidation-reduction potential （ORP） and electrical conductivity （EC） did not show difference between the two regions. The concentrations of various forms nitrogen and phosphorus in water of the FAB region were significantly lower than those in water of the AB region, and fluctuated slightly with sampling time. In the AB region, howev- er, the concentrations of TDN, NO3 - -N, NH4 ＋ -N, TN, TDP and PO43- -P in water showed downward trend during the AB for- mation process and the early stage of AB outbreak process, followed by upward trends during the later stage of AB outbreak and the AB extinction process. The concentrations of total nitrogen, total phosphorus and total organic matter in sediments of the AB region were significantly higher than those in sediment of the FAB region, and they showed different change trends with samplin