中文摘要：

对苏州市古城区南园水系的水质和藻类1a的监测结果表明,研究区域水质污染主要以NH4＋-N和TN的严重超标为特征,最大超标倍数可达到5倍以上[按地表水环境质量标准（GB 3838-2002）Ⅴ类水作为基准];经镜检,底栖附泥藻类共34种,种类数以硅、绿和蓝藻类占优势,其数量和生物量极高,达到2 145.5×10^4个/mL,生物量3.524 mg/mL,远高于相同点位浮游藻类监测结果,数量和生物量以硅藻和蓝藻占绝对优势;各门藻类在各河段中分布极不均匀,优势种群多属异养型或两型营养特征,且与河道的污染特征有较密切关系,这些典型藻类包括：蓝藻门（Cyanophyta）中的两栖颤藻（Oscillaria amphibian）,硅藻门（Bacillariophyta）中的小环藻（Cyclotellasp.）、直链藻（Melosirasp.）、冠盘藻（Stephanodiscus hantzschii）、舟形藻（Naviculasp.）、菱形藻（Nitzschiasp.）、异极藻（Gomphonema）等.其数量季节变化表现为：夏季〉秋季〉春季〉冬季;而生物量则为：冬季最高,春、夏、秋相对较低,且变幅不大.相关研究成果可为城市重污染河道生态恢复提供参考．

英文摘要：

The water quality and algae community of Nanyuan Water System in the old city area of Suzhou were monitored for a year. Results showed that the water pollution in the studied area was mainly related to nitrogen （NH4^＋ -N and TN）. Sometimes, they even exceeded the Environmental Quality Standards for Surface Water （ GB 3838-2002, PRC ） more than 5 times. 34 species of benthic epipelic algae were observed by microscope, and the species amount of diatom algae, green algae and blue algae are more than others. Their abundance and biomass are far higher than that of the pelagic algae in the same sites, and reach 2 145.5 × 10^4 cells/mL and 3.524 mg/mL, respectively. The dominant species of benthic epipelic algae in Nanyuan＇s water system are diatom algae and blue algae, most of which belong to the heterotrophic type or bi-trophic type algae, the typical genera include ： OsciUaria amphibian （ affiliated to Cyanophyta ）, Cyclotelln sp., Melosira sp., Stephanodiscus hantzschii, Navicula sp. , Nitzschia sp. , Gomphonema （affiliated to Bacillariophyta） and so on. And their distribution of species and abundance are very nonuniform in different reach of heavily polluted city river, which relates to the pollutant characteristics of the river. The seasonal variety trend of the abundance for benthic algae showed that ： summer 〉 autumn 〉 spring 〉 winter, and that of biomass for benthic algae showed that：the biomass in winter is the most of four seasons and change extent of the biomass is not obvious in spring, summer and autumn. The research results can provide reference for the ecology restoration of city heavily polluted river.