Biological Monitoring Technology Of Water Quality By Using Benthic Diatoms In Longjiang River

In recent years, the river water pollution incidents have occurred frequently.It is an urgent need to improve the water quality monitoring technology. In order to effectively prevent and treat,warn or predict the pollution of the river, it is necessary to adopt efficient and reliable means of monitoring water quality. Diatom water quality monitoring technology is used and researched widely, and it is an ideal means of water quality and ecological quality monitoring of the river.This paper studies the characteristics of benthic diatom communities and the relationship with the environment in Longjiang River basin, We use several mathematical methods to select diatom index evaluation of water quality of Longjiang River Basin, and evaluate the Longjiang water quality and ecological quality using benthic diatoms. Conclusion and innovation as follows:First. In May, diatom assemblages were collected from14sites in Longjiang River Basin.Altogether2classes6orders8families and30genera110species were identified; In September, diatom assemblages were collected from20sites in Longjiang River Basin.Altogether2classes6orders8families and30genera163species were identified. The dominant genera of two samples are both Navicula, Achnanthes and Cymbella, but there are great differences in the dominanted species; The distribution of the various samples of algae reflects heterogeneity of the diatom communities in different time and space, but the widespread distribution of the species is much the same.Second. Studied the effect of environmental factors on the benthic community variability and spatial distribution of diatoms in Longjiang River. RDA analysis showed that eight environmental factors explained51.3%of the variation in the diatom community, and filter out dissolved oxygen temperature, conductivity and altitude to influence diatom communities and spatial variability the distribution of significant factors could explain30.9%variation in the diatom community structure, environmental factors explained60.23%of the total amount. Diatoms relative density, the number of diatom species and environmental factors related to analysis, cluster analysis and regression analysis showed that there is no significant correlation between the number of diatom species and environmental factors, and the relative density of the diatoms and there is a significant elevation correlation.Third. The applicability of16diatom indices were studied by correlation analysis, principal component analysis, optimal segmentation classification, box-whisker plot method, stepwise discriminant analysis and two-way indicator species analysis and other mathematical methods in the river water quality biological monitoring about the Longjiang River. Physical and chemical water quality composite score derived by principal component analysis, the optimal method of water quality in turn divided into four categories. Box-whisker plot method and correlation analysis method first elected EPI-D, IBD, IPS, IDP, TDI index. Use principal component analysis score again, and then the best method to sample split into four categories, for five diatom indices stepwise discriminant analysis, consider the introduction of a combination of different indices all31kinds of classification. combination of IPS and TDI twice a correct classification rate of100%and94.4%, respectively, the two-dimensional clustering effect of Fisher discriminant function is also the best, have the best water quality classification ability. Continue through two-way indicator species method, considering the ecological properties of diatom communities and produced four different groups, IPS and TDI of water quality classification of the box-whisker plot showing a reasonable trend. The results show that the IPS and TDI index showed reasonable trend sample as well as Box-whisker Plot, at the same time, the IPS and TDI had a good correlation with environmental factors, other diatom indices and each other, which indicated that the IPS and TDI were applicated to water quality biological monitoring and evaluation.Fourth. A combination of diverse index, diatom biological index, diatom ecological groups and the physical and chemical indicators of evaluation method validation method combined with GIS technology Longjiang water quality evaluation, and proposed DIR, water-based comparative evaluation of diatom indices.Discover the diversity index of water quality is not suitable for the evaluation of Longjiang, various evaluation methods have their own characteristics, for scientific and practical research, the joint adoption of a variety of water quality assessment methods are necessary.Fifth. Overall, the water quality in longjiang in May is poorer than that in September; the diatom relative density of upper reaches is greater than the downstream, and the water quality is relatively good. Diatom species of diatoms trends substantially opposite relative density changes, but changes in water quality and the number of species showed no obvious regularity.