中文摘要：

为了保护极度濒危的长江江豚（Neophocaena asiaeorientalis asiaeorientalis）,了解其生活水域长江新螺段白鱀豚自然保护区水质的时空变化特征,探究水质状况的季节变化与地理变化差异,选用1992-2008年长江新螺段的水质监测数据资料,利用Kendall非参数趋势检验法分析枯水期、平水期和丰水期水体中溶解氧（DO）、氨氮（NH3-N）、总磷（TP）和总氮（TN）的变化趋势,并于2013年4月至2014年1月对该江段18个监测点的水温（T）、溶解氧（DO）、电导率（EC）、p H、总氮（TN）、总磷（TP）、硝态氮（NO3-N）、亚硝态氮（NO2-N）、氨氮（NH3-N）和六价铬[Cr（Ⅵ）]共10种水质指标进行监测分析。Kendall检验结果表明,1992-2008年长江新螺段水质状况整体无显著性变化,其季节性变化特征为枯水期水体污染物浓度高于平水期和丰水期。2013-2014年的水质监测结果表明,与2008年前相比,长江新螺段水质状况明显恶化,水体中的TN、TP和Cr（Ⅵ）污染情况较为严重,其中TP和Cr（Ⅵ）的平均浓度均超过Ⅳ类水质标准,且水质季节性变化特征也发生了相应改变。层次聚类分析将长江新螺段的18个监测点分为5个地理组,水质指标差异比较结果表明,陆溪河口的水质状况最好;临湘市化工园区排污口的水质状况最差,是长江新螺段的主要污染源;洪湖市生活废水的输入可能是新港码头附近水域中NH3-N浓度较高的原因。

英文摘要：

The Yangtze finless porpoise （Neophocaena asiaeorientalis asiaeorientalis）, the only freshwater subspe- cies of finless porpoise, lives exclusively in the main channel of the Yangtze River and Poyang and Dongting lakes, both linked to the river. The population of the Yangtze finless porpoise has dropped significantly in the past 30 years and the decline is accelerating. Water pollution is one of the primary factors threatening the species. The Xin- luo section, along the middle of the Yangtze River, is important habitat for the Yangtze finless porpoise. The dra- matic population decline in this section demands a better understanding of habitat conditions. In this study, the temporal and spatial variations of surface water quality were investigated in the Yangtze Xin-Luo Baiji National Na- ture Reserve. Water samples were collected at 18 sampling sites in April, July, October of 2013 and January, 2014. 100 mL water samples were collected at a depth of 50 - 80 cm and water quality parameters were determined within 36 hours. Water temperature （T）, dissolved oxygen （DO）, electrical conductivity （EC）, and pH were de- termined in situ using a YSI proplus multi-parameter water quality analyzer. Nitrate nitrogen （NO3-N）, nitrite ni- trogen （NO2-N）, ammonia nitrogen （NH3-N） and hexavalent chromium [ Cr （VI）] were determined using a Smartchem 200 automatic chemical analyzer. Total nitrogen （TN） and total phosphorus （TP） were determined with a Hach DR/2400 portable spectrophotometer. Water quality data for the Xinluo section from 1992 to 2008 （ provid- ed by environment monitoring station of Honghu, Hubei Province） were also assimilated and the variations of DO, NH3-N, TP and TN in dry, normal and wet seasons were analyzed using the Mann-Kendall non-parametric test method. The analysis indicates no significant change in the water quality in Xinluo section of the Yangtze River from 1992 to 2008 and that pollutant concentrations were higher in the dry season than in the wet and norm