Study On Behavior And Mechanism Of The Nutrient Release From Urban River Sediment At Plain River Network Area

Water eutrophication is a phenomenon of water pollution. At plain river network area, channels are densely distributed. Most of the inner channels don't connect with the outer water system. The water flow is slow and sediment deposition is serious. And water quality of urban channels has become worse. When the environmental conditions changes, pollutants accumulated in sediments will release to the overlaying water, increasing pollution load of water body. Therefore, it's significant for restoring the ecosystem of urban channel to strengthen the researches on pollutant release from sediment and the control measures.This study is one of the main research contentses of the third topic of the key national high-tech program(863) during the tenth-five year period in China —"water envirment improvement and demonstration in Suzhou ", "overall plan for water envirment improvement at the old city area of Suzhou ". And this paper studied the internal source pollution of urban channels through bench scale experiments of pole-core sample taken from urban channels. The main study contents are as following.(1) Study on the effects of environmental factors on the nitrogen release from urban channel sediments. This paper is focused on the NanYuan River in Suzhou City. We studied and discussed the nitrogen release from sediment under different environmental conditions such as nutrient level, DO level, temperature, Eh etc.(2) According to the statistical analysis of the experimental results, the exchange principle of pollutant between water and soil was discussed. The main factors which affect the release rate were selected.(3) According to the nitrogen release rate gained from experiments, the release amount of nitrogen from the urban channels was estimated. In this paper, the channels in old city area of Suzhou were divided into 70 segments. The release amount of nitrogen of all the channels was estimated by surface area method. It can provide theoretical basis for calculation of internal pollution load of urban channels.