Research On Nitrogen And Phosphorus Pollution Of The Great Canal In Hangzhou City And Hydrodynamics Of Phosphorus Release From The Sediments

The Great Canal is the culture lightscape and traffic venation of Hangzhou city. Since the 1980's, water quality of the Great Canal had degenerated as a result of the long-term negligence of environment protection. Thanks to the environment protection for the Great Canal since the 1990's, organic pollution has been decreased obviously, but the eutrophication has not been controlled effectively. Eutrophication control will take the place of organic pollutant removal to become the most important way of the Great Canal treatment. As a substaintial component of river, the sediments are important storeroom of N and P. Under certain conditions, the internal Phosphorus can be released into water which can deteriorate the eutrophication or hamper the restoration process. Coupled with analysis of historical data and field survey, the evaluation of the N and P pollution in water and P pollution in sediments were undertaken. At the same time, taking internal P as object, hydrodynamics effect on the release and stability of different P forms was studied and a relative model was established based on it.The investigation results of pollution status of N and P in the Great Canal indicated that the pollution was serious, especially for N, whose indicator far exceeded the standard of IV water quality classification. Although P pollution was lightened to a certain extent, the N/P index went beyond 7.2 far away which demonstrated P as a restricted factor for eutrophication in Hangzhou city's rivers.The P accumulation of sediments in Dongxin river was at a high value, whose average value was 1.5g/kg. The major forms of inorganic P were Al-P or Ca-P. More Fe-P or Al-P was found in the sediment with the productive waste water as the major input, but for the sediment with the domestic waste water as the major input, Ca-P was the main form.Geostatistics and GIS were integrated to produce point vector graphs for spatial out-fall and sediment samples distribution. The results showed that point-pollution made significant contribution to P loading in sediment whose concentration has notable relationship with the number of out-fall, P concentration in polluted water and...