The Study On Phytoplankton Structure Characteristic In Excavating Coal Subsidence Pool

In recent years, along with the increasing of the exploitation of coal, the area of excavate coal subsidence are extended and it caused the mineral area ecological environment to get worse. Excavating coal subsidence pool was caused by the exploitation of coal in mine, result in earth's surface descend and cave and become water body that is similar to lake. But compared with lake, subsidence pool is the special component of the surface water. So far, there are very few study cases to confirm the ecological environment difference between excavating coal subsidence pool and non-mineral area lake. In this paper, we selected Xieer Mine subsidence pool and natural lake -Gaotang Lake for a comparative analysis. In order to discussing the difference of the characteristic of phytoplankton structure and its influencing factors, we studied the characteristic of phytoplankton structure. This study provides a theoretical basis for the improvement of ecological environment of excavating coal subsidence pool.Xieer Mine subsidence pool and Gaotang Lake were investigated monthly from April in 2005 to March in 2006. Such physical-chemical indices as water temperature, depth, transparency, pH value, conductivity, chloride, total hardness, DO, BOD₅, COD as well as Chla and such nutrient indices as TN, TP'were measured, the phytoplankton species and abundance were identified and counted with microscope at the same time. The monthly ecological feature of phytoplankton community including the species composition and their abundance, the dominant species, the indicator of pollution, the succession and similarity as well as the character index( diversity index, evenness index, abundance index, prevalence index and simplicity index )were preliminary studied in Xieer Mine subsidence pool and Gaotang Lake.The main conclusions were summarized as follows: The organic pollution of Xieer Mine subsidence pool is serious than Gaotang Lake, the chloride and total hardness are twice as Gaotang Lake, seasonal variation of nutrient salt are different. To some extent, because of the difference of physical-chemical factors and nutrient salt that arc the factors affecting the composition of phytoplankton dominated by the species of green-blue algae, the dynamic variety in phytoplankton abundance was influenced by temperature and nutrient in Xieer Mine subsidence pool. While thedominant species are blue-green algae and diatom in Gaotang Lake, the change in temperature influenced the phytoplankton abundance significantly. Annual variations of the phytoplankton in Xieer Mine subsidence pool show a typical double-season alteration and it in Gaotang Lake show a multiple alteration.