Variation Of Water Quality And Sediment Internal Loading In Shanzai Reservoir As The Second Drinking Water Source For Fuzhou City

Shanzai reservoir is one of the important freshwater resources in Fujian province, and also the second drinking water source for Fuzhou city, so the water quality directly affects Fuzhou citizen's health. Recently ,because of the wastewater discharge from living , net culturing, hoggery, runoff, etc., especially, excessive loading of dissolved and particulate organic matter and inorganic nutrients (N and P), the quality of reservoir has deteriorated. At the end of 2000, "The measures of protecting and managing Aojiang area" was promulgated by Fujian province, and excessive loading of nutrients was forbidden to enter the reservoir directly. In short term, the water quality has been gradually restoring in the surface water, but after a while a steady increase in eutrophication has been observed subsequently. Eutrophication may be maintained by internal loading, which corresponds to the release of nutrients from the reservoir sediment into the water column. Based on above background and the data obtained, the thesis discusses the essential reasons for the waterbody of eutrophication , furthermore, studies that potential internal loading of nutrients from the sediments to water column. This research not only provides the scientific base to manage and control Shanzai reservoir , but also has the advantage of other reservoirs' control in Fujian province.This thesis primarily draws several conclusions, as follows : 1 By comparison of the water quality in 10 years, some results are obtained .(1)For different seasons, the water quality of the wet season is the worst of all, and that of the dry season is better than that of the normal season ; for different sites ,the water quality of Huokou is worse than that of the other three sites ,and the water quality is worse at Rixi and Xiaocang, but the water quality of Baqian is improved ,which indicate temporal pattern has a direct relation with precipitation and domestic pollution source . (2)Chla has a remarkable correlativity with PH CODMn and the amount of alga.(3)Water quality is decreasing along current .DO and PH is decreasing along from surface to bottom , so the bottom of reservoir is anoxic and feeble acid condition, while TN and TP are increasing along vertical bearing at Shanxiuyuan and Baqian. 2 The adoption of Attribute recognition theory to evaluate eutrophicationfor different periods and inter-annual, the results showed that trophic state of 1997-1999 and 2003 is eutrophic ,and trophic state of 1996, 2000-2002 is in the middle of mesotrophic and eutrophic level; for one year , trophic state of Aug. Sep. and May is worst of a whole year ,and that of Feb, Mar, Apr, and Jun is worse, and Oct, Nov, Dec, and Jan is best .Furthermore, trophic state corresponds to different pollution well. 3 Nutrient exchange patterns between sediment-water interface was simulated with the soft-sediment core samples at different temperatures (due to seasonal changes) in the laboratory, and we drew several conclusions: The average speed of release of TP is 1.996 (15X2) mg/m2 d, 2.873 mg/m2d (25C) and NH/-N is 47.09 mg/m2 d (15C) ,59.45 mg/m2 d (25C) respectively .And then ,applying GIS photo of remote sensing and relief map ,the result shows that the internal loading of TP and NH/-N are 4.51t/a and 120.25t/a,respectiveIy. At the same time, the release intensity is increasing along current.