Abstract:

Experiment points were set up in Liujiang river and a multi-index system of diatom is built up in order to effectively monitor water quality and improve physicochemical analysis. According to the results of correspondence analysis in different water functional zones of different water quality, AMIN, GOLI, DDEL, AMSA, ACLI, NAAN and NRHY are classified as clean species in the Liujiang river whereas Nitzschia and Luticola are stain species. Canonical correspondence analysis shows that the river water quality parameters are the main factors affecting the distribution of diatom communities. Nitrates, chlorides, total number of Fecal coliform and total phosphorus are the main variables, and physicochemical parameters are main variables based on the results of factor analysis. The results show that physicochemical variables are closely related with diatom indices IPS,IBD,TID, IDG and SLA. According to the water quality level from long-term monitoring and the data about clustering of water quality parameters and diatoms population, they are classified into three different water quality categories. IPS, IBD and CEE work well on the evaluation of water quality of the three categories while the diatom’s bio-diversity index are unsuitable for the evaluation. Through biological indices IBD and IPS, and VAN groups to divide eutrophic species percentages and physicochemical parameters, multi-index evaluation can be used to evaluate the quality of river water and ecological quality in order to improve the reliability of the evaluation.

Key words: Liujiang river, water function zoning, epiphytic diatom, diatom indices, water quality assessment