中文摘要：

2010年分4个季度对洪泽湖全湖20个样点的水质理化特征进行了定期监测，采用修正的卡尔森营养状态指数法（TSIm）综合评价了洪泽湖水质的营养状况，同时应用主成分分析（PCA）和自组织特征映射网络（SOM网络）分析了洪泽湖水质的时空变化特征。结果显示：除了水深（WD）和透明度（SD），洪泽湖的pH、EC、NHt-N、TN、TP、和COD。。等水质参数季节差异显著。TSIm综合评价结果表明洪泽湖4个季节的水质均呈富营养化状态，夏季富营养化程度最严重。PCA分析表明洪泽湖水质主要受离子和氮盐的控制，磷不是控制洪泽湖水质的最主要因素。SOM网络将全湖20个样点聚为G1、G2和G3三类，G1代表洪泽湖相对封闭的北部区域，有沉水植被分布，水质主要受围网养殖污染的影响；G2代表洪泽湖东部和南部区域，航运繁忙，直接承接淮河入湖河水，水质主要受淮河入湖河水和航运的影响；G3代表洪泽湖西部水域，沿岸密布养殖池塘且人口密度大，水质主要受养殖废水和城镇生活污水的影响。研究认为，控制外源污染和恢复沉水植被是防治洪泽湖富营养化的有效途径。

英文摘要：

The physicochemical characteristics of water samples collected from 20 sampling sites in the Hongze Lake were periodically monitored in 2010. Modified Carson＇s trophic state index （TSIm） was used to evaluate the nutritional status of water quality. Spatial-temporal distribution variation characteristics of water quality were analyzed by using principal component analysis （PCA） and self-organizing feature map （SOM）,and the spatial temporal differences were discussed.The results indicated that the water physicochemical parameters had significant seasonal variations except water depth （WD） and secchi depth （SD）. Total phosphorus （TP） and permanganate index （CODMn,） were the highest in winter, while nitrogen content was the highest in spring.The water quality was mainly influenced by the ionic and nitride concentration, and the total phosphor was not the dominating control factor.The results from TSI indicated that water quality was in the state of eutrophication at the four seasons and was the most severe in summer.The comprehensive evaluated scores based upon PCA were 0. 178,0. 404,--0. 651 and 0. 071 in spring, summer, autumn and winter, respectively, which also indicated that water quality in the Hongze Lake was the best in autumn and the worst in summer.In 2010,TP declined significantly and TN scarcely differed from that in 1989. However, the contribution of inorganic nitrogen such as ammonia nitrogen （NH4^＋-N） and nitrate-nitrogen （NO3^-N） to TN increased, which might be relevant to mass use of fertilizer and feed in the process of continuous development of planting,aquaculture and livestock industry in the watershed of the Hongze Lake.The results of spatial characteristics of water quality from SOM and hierarchical cluster analysis （HCA） had some differences, but most of the results were consistent with each other. Compared with the HCA, the SOM results were further accord with the actual situation and were able to more clearly and accurately reflect the spatial char