Characteristics Of Diatom Community And Influence Factors Analysis Of Yintan Wetland

Diatom as a kind of single-cell algae responds to changes of water condition sensitively, such as eutrophication, organic pollution, heavy metal, temperature, pH, specific conductance, metallic element and other environmental variables, all changes of these factors will influence the structure and quantity of diatom. The cytoderm of diatom is formed of Si, which can be kept in sediments for a long time. Because of these, diatom is used as biological indictor to evaluate water quality and reconstruct paleoenvironment. By now, many people have used diatom successfully in these fields. Yintan wetland is the sole wetland park in Lanzhou and the water is led from Yellow river. It plays an important role in climate regulation. This paper aims to monitor the water quality of Yintan wetland by surveying the diatom community. At the same time, the environmental factors are measured to analysis the correlation. We get the following conclusions.First, both the characteristics of diatom community and CCA, PCA analysis show that the water is polluted. The water is polluted by organic matter and heavy metal. What’s more, the alkaline water is of better condition in the riverway than in the abyssal region. In spring and autumn, the diatom population is more abundant than in summer and winter.Second, in this research, Navicula and Nitzschia are the dominant species. The diatoms are characterized by the benthonic and settled species. Navicula exigua、Gyrosigma scalproides and Cymbella can be the indictors of low concentration of nutriment. On the contrary, Gyrosigma acuminatum, Nitzschia palea and Fragilaria brevistriata can be the indictors of eutrophication. Nitzschia palea, Navicula viridula var.rostellata, N.veneta and N.simplex stand for the environment which is polluted by organic matters. Navicula exigua and N. radiosa show the same feature, but they can only endure low concentration of organic matters.Third, the analysis of diatom assemblages and environmental factors show that TOC, Cl", Fe, Si, Ca, Mg, SC, pH and T (℃) play an important role in the distribution of diatom assemblages. Because much of the diatoms are organic polluted species, so TOC, Cl-,Si, SC, pH and T (℃) play a more important role. Other factors mainly influence the species favour of clean water.