Southern Shandong Mine Subsidence Bred Water Environment Assessment And Water Purification Effectionn Study

China is the largest producer and user of coal in the world. About4%of these is strip mining, and96%is underground mining. The Mined-outareas, which were formed by underground mining, usually lead to surfacecollapse. At present the area of broken land has already exceed4million ha,and is still on the increase with the speed of33,000~47,000each year. Thelarge-scale coal mining throughout the year and the lower ground waterlevel resulted in ground movement, land subsidence, ponding in basin andthe farmland were inundated by flood, so the mining coal collapse watersarea would be formed. The main water sources of collapse area are coalmine water, underground water and atmospheric precipitation. These watersources had pollutants. They would import many ions, such as calcium,magnesium and potassium, organics, nitrogen and phosphorus to collapsewaters area. It could change the physicochemical environment of collapsearea, and make the area showing the characteristics of coal mining area.Aquaculture pond is an artificial system, and the ecosystem of it isvery different with natural ecosystems. The cultural aquatic animals has agreat advantage in the community of system. This advantage was formed by human beings. The high-density and intensive farming mode caused alot of residual feed, excretion and remains of plants and animals depositingon the bottom of the pond. At the same time, a lot of artificial feed,disinfectants, antibiotics, pesticides and heavy metals were put intoaquaculture system. The structure and function of the system had a series ofchanges, which resulted in the lower ecological buffering capacity andvulnerability. The huge biomass of cultural aquatic animals would destroythe ecological system and biological diversity.This article chose two collapse areas of Zhoucheng City and YutaiCounty, Jining City as the research area. Based on the investigation data inaquaculture ponds and large water surface of these two areas. The waterquality and nutrient condition of these areas were also evaluated. Thepurification function experiment with Ipomoea aquatic used the currenteconomic and efficiency biological floating repairing mode in aquacultureponds in Zhoucheng City. The purification function experiment withEichhornia crassipes, Pistia stratiotes and Alternanthera philoxeroides wasmade in the aquaculture ponds, which were changed from collapse areas inYutai County. This research would provide scientific basis for ecologicalculture and efficient water-saving in collapse areas.Based on the investigation data in the large water surface, big pondsand aquaculture area in Zhoucheng City, Jining City from May2012to October2012, the variation tendencies and characteristics of surface watertemperature, pH, transparency (SD), dissolved oxygen (DO), chemicaloxygen demand (COD), sulfate (SO42+), Chl a, common heavy metal ionsand nutrients were analyzed. And the water quality and nutrient conditionof these areas were also evaluated on the basis of investigation data. At thesame time, the purification function experiment with Ipomoea aquatic wasmade in aquaculture ponds in Zhoucheng City from May2012to October2012. The purification function experiment with Eichhornia crassipes,Pistia stratiotes and Alternanthera philoxeroides was made in theaquaculture ponds in Yutai County from May2013to October2013. Themonitoring projects involved pH, dissolved oxygen (DO), chemical oxygendemand (COD) and nutrients. Based on the experimental results, thepurifying effect of floating beds of different coverage area and differentaquatic plants. Results are as follows:(1) The water quality in collapse area in Zhoucheng City compliedwith the Grade Ⅲ or even worse than Grade Ⅲ, TN, TP and COD evencomplied with the Grade Ⅴ. The variations of nutrients concentration wasrising gradually with the extension of culture, and the every indicator of thelarge water surface was less than this in other two cultivation areas.(2) The eutrophication results show that the three indicators of waterquality are above slight eutrophication level, the eutrophication level of big pond and intensive pond is higher, reaching moderate eutrophication level.(3) that the pool with Ipomoea aquatic floating bed had significantbetter purification effect than that without Ipomoea aquatic floating bed onTN and TP. And with the greater coverage, the floating bed reached betterpurification effect on TN, TP, NH4+-N, NO2--N, COD. The present studyshowed that, mining subsidence aquaculture water was good purified byIpomoea aquatic floating bed, and when the area of floating-bed was30%,the ecological benefit achieved to the optimum level.(4)To Pistia stratiotes, TN and TP of30%coverage is evidently lowerthan the20%coverage and the10%coverage, NH4+-N、NO3--N、NO2--Nshows a similar trend. That shows the best purification of Pistia stratiotesis30%coverage.(5)To Eichhornia crassipes, TN and TP of10%coverage is the highest,TN and TP of20%coverage is the lowest, NH4+-N、NO3--N、NO2--N showsa similar trend. That shows the best purification of Eichhornia crassipes is20%coverage.(6)The TN and TP of each experimental group are declining orunchanged,which indicated that these three selected plants purifysubsidence area water. The results of comparison in these three plantsshows that the TN of Alternanthera philoxeroides and Pistia stratiotes ishigher than Eichhornia crassipes, the TP of Alternanthera philoxeroides is higher than Pistia stratiotes and Eichhornia crassipes. The differenceamong NH4+-N, NO3--N, NO2--N, COD, DO and pH in these three plantswas not significant. This explained that under the conditions in theexperimental, the best purification in subsidence area is Eichhorniacrassipes, and the best coverage is20%.