基于硅藻完整性指数的辽河上游水质生物学评价

2010年9月对辽河上游12个采样点的着生硅藻进行了生物调查,同时测定了ρ(DO)、pH、ρ(TP)、ρ(TN)、ρ(NH3-N)、ρ(CODCr)和ρ(BOD5)等水质参数.共检测到硅藻16属,以针杆藻属(Synedra sp.)、舟形藻属(Navicula sp.)、异极藻属(Gomphonema sp.)、桥弯藻属(Cymbella sp.)为优势种.根据硅藻香农多样性指数确定了5个相对清洁采样点和7个受污染采样点,对10个硅藻生物指数进行了辨别力分析和Pearson相关分析.结果表明,硅藻香农多样性指数、敏感性硅藻百分比和IDP硅藻指数最适合辽河上游的水质生物学评价.采用5、3、1生物指数记分法统一量纲后,获得变化范围在3～15的D-IBI(硅藻完整性指数).利用四分法划分辽河流域水质级别的标准,13～15为较好,10～12为一般,7～9为较差,3～6为差,并对12个采样点进行了重新评价,评价结果与水质参数的评价结果一致.总体看来,该D-IBI基本适宜于评价辽河上游的水质状况.

Bioassessment of Water Quality Based on Diatom Index of Biotic Integrity in the Upstream of Liaohe River

In September 2010,diatom assemblages were collected from 12 sites in the upstream of Liaohe River.Dissolved oxygen,pH,total phosphorus,total nitrogen,chemical oxygen demand,ammonium nitrogen,and biochemical oxygen demand after five days were measured.A total of 16 kinds of algal genera were identified,which were dominated by Synedra sp.,Navicula sp.,Gomphonema sp.and Cymbella sp.Based on the Shannon diversity index of diatom discriminatory criteria,five sites were distinguished as clean,while the others were polluted.The result of discriminatory power analysis of 10 metrics showed that five metrics were suitable for bioassessment of water quality in the upstream of Liaohe River: percent sensitive diatoms,Shannon diversity index of diatoms,PTI,TDI and IDP.The result of Pearson’s correlation analysis of the five metrics indicated that Shannon diversity index of diatoms,percent sensitive diatoms and IDP were the most suitable for bioassessment of water quality in the upstream of Liaohe River.A score on a scale ranging from 3 to 15 for diatom index of biotic integrity(D-IBI) was obtained after a score of 5,3 or 1 was assigned to each metric for metric standardization.Four levels of discriminatory biocriteria for water quality were eventually proposed by quarters: 13 to 15 is good,10 to 12 is fair;7 to 9 is slightly poor and 3 to 6 is poor.The results of re-evaluation of the 12 sites using the four levels of discriminatory biocriteria were the same as the water quality parameters.Therefore,D-IBI was proven to be a biocriterion which is suitable for the assessment of the water quality in the upstream of Liaohe River.