运用主成分分析法评价北京市代表性河流的水质与毒性状况

以北京市3条具有不同功能的代表性河流(清河:纳污排洪;京密引水渠:供水水源;小月河:景观用水)作为研究对象,分析测定了33个水质指标,采用内梅罗指数法与大型蚤急性毒性测试法对3条河流的水质与毒性状况进行了评价,同时运用主成分分析法对毒性产生的原因和影响水质的因素进行了初步探讨.结果表明,1)3条河流已受到不同程度的污染,水质和毒性状况均不容乐观.作为纳污排洪的清河大部分采样点水质较差,生物毒性极高;作为景观用水的小月河水质一般,具有一定的生物毒性;作为供水水源的京密引水渠水质一般,但毒性较低.2)水样生物毒性与Cl-、Ca、K、Li、Mn、Na、Cr、Ni等指标有关;内梅罗水质指数与NO2-、Cl-、K、Na、Ni等指标有关.3)某些指标(如NO2-)超标会对水质分级产生较大影响,但对生物毒性贡献不大,而低浓度的重金属,不会对水质分级产生贡献,却会对生物的生理活动产生影响,综合化学指标和毒性指标共同评价水质更为合理.

Study of River Water Quality and Bio-toxicity in Beijing by Principal Component Analysis Method

Three representative rivers with different function in Beijing(Qing River: waste drainage river; JingMi diversion canal: potable water supply; XiaoYue River: not directly osculant recreational water)were selected. Water samples collected from three representative rivers were analyzed for thirty three various physical-chemical characters. Water quality and bio-toxicity of three representative rivers were evaluated by Nemerow Index method and Daphnia acute toxicity test, respectively. The results showed that three rivers were contaminated at varied extent. The toxicity of Qing River as waste drainage river was extremely high and water quality was bad. XiaoYue River as not directly osculant recreational water had some toxicity and water quality was moderate. The reason and factors affecting water-quality and toxicity were simply discussed by Principal Component Analysis method. The results showed that the toxicity had relation with Cl-,Ca,K,Li,Mn,Na,Cr and Ni. And Nemerow Index had relation with NO2-,Cl-,K,Na and Ni. Some factors(eg. NO2-)exceeding standard can affect water quality classification but not contribute to bio-toxicity. Low concentration of heavy metals can bring bio-toxicity to organisms but may not affect water quality classification.