用硅藻群集指数(DAIpo)和河流污染指数(RPId)评价珠江广州河段的水质状况

用硅藻计于1990年采集珠江广州河段的9个采样点的附着硅藻群落．共得硅藻24个属，170个分类单位，其中，适腐性种8个，广腐性种84个，仍腐性种78个．群落相似性聚类分析表明，位于前、后航道中部的员村（st3），新造（st8），沙浴村（si10）三点的硅藻群落结构是为相似，向上，下游相似性逐渐减小．用硅藻群集指数（DAIpo）和河流污染指数（RPId）对各采样断面的水质进行分析表明：大盛（st12）和莲花山（st5）两点受污染最轻，属β-寡污带，黄沙点（st2）污染最严重，属α-中污带．对照点鸦岗（St1）也受到一定的污染，属α-寡污带，其它点的污染程度在α-寡污带与β-中污带之间．DAIpo值与BODS存在着显著的负相关（r＝0．86）．珠江广州河段的前、后航道的污染程度相差不大（RPId=56．42，56.26），均属中度污染．

EVALUATION OF WATER QUALITY OF THE PEARL RIVER BY USING DIATOM ASSEMBLAGE INDEX (DAIpo) AND RIVER POLLUTION INDEX (RPId)

Diatom assemblages on the diatometers were collected from 9 sampling sites ofthe Pearl River at Guangzhou section. Twentydriur genera with 170 diatom taxa wereidentified. Amng them, there were 8 eusaprobic, 84 eurysaprobic and 78 casually saprobictaxa. Conunnity sindlarity cluster analysis showed that the connnnity composition wasmost similar among sites at Yuancun (st3), Xinzao (st8) and shalu0cun (st10) situated atthe middle of Guangzhou section, the commnity sindlarity being reduced gradually at theupper or lower reaches of the river. The diatom assemblage index (DAIpo) values indicatedthat Lianhuashan (st5) and Dasheng (st12) were least polluted which belonged tothe goligosaprobic type, while Huangsha (st2) was most seriously pol1uted and was ofacoosaprobic type- As a site for comparision, Yagang (st1) was also slightly affectedwith pollution, indicating the axiligosaprogic character. The polution of the remaining siteswere between axiligosaprobic and gasesosaprobic. DAIpo had a good negative correlationWith bio1ogical oxygen demand (BOD5) (r=O.86). River pollution index raPId) values ofthe front raPId=56.42) and rear channels (RPId=56.26) of the Guangzhou sectionindicated that the water in these two channels were polluted at a ndddle level.