中文摘要：

地表水环境问题对城市经济社会发展、水质改善及人居生活质量有较大影响。为了解近年来苏州市吴中区水质状况,提高水体服务功能,利用2011—2013年苏州市吴中区各监测站水质监测及我们实时观测等数据对吴中多年城市水质特征进行了定量评价。研究结果表明,吴中区水质状况月际变化明显,整体来看化学需氧量（COD）、生化需氧量（BOD）在11—2月份较高,3—6月份较低,7—10月份升高;总氮（TN）和总磷（TP）的变化趋势趋于一致;上游南支流浒光河和木光河各项指标浓度均最低,其水质最好,中游苏东运河COD、BOD、粪大肠菌群值都较高,下游吴淞江TP、TN含量较高,水质较差。水质指数评价得出,吴中区2011—2013年整体水质尚好,主要污染因子是TN、TP和COD,平水期和丰水期水质优于枯水期。

英文摘要：

Surface water environment issues have a great impact on urban economic and social development, as well as people＇s life quality. To understand the water quality and to improve the service function of water in the Wuzhong District ,Suzhou, the water quality data from the monitoring station in 2011--2013 were used to evaluate the water quality characteristics. The integrated water quality index （WQI） was also evaluated to demonstrate the condition of water quality. The results showed that the inter-monthly varia- tion of water quality was obvious, chemical oxygen demand （COD） and biochemical oxygen demand （BOD） from March to June were lower and higher from November to February; the changing trend of total nitrogen （TN） and total phosphorus （TP） were similar; Huguang River and Muguang River, the northern branches of upstream, had the best water quality, for the pollution indexes were low-est; Sudong Canal, the middle reaches, was higher in COD, BOD and fecal coliforms, Wusong River, the downstream, was higher in TP and TN. The WQI results showed that the water quality in Wuzhong District was in fine condition, the major pollutant were TN, TP and COD, the water quality in rain and normal seasons were better than that in dry season.