白洋淀府河中氮的来源与迁移转化研究

采用δ15N示踪法对白洋淀府河中含氮污染物来源以及氮的沿程迁移转化进行了研究.结果表明,府河氨氮(NH 4+-N)和硝氮(NO 3--N)中δ15N分别为1.35‰～8.01‰,-6.69‰～8.36‰.府河氮污染物的主要来源为保定市生产生活废水,农业面源对河流氮污染的贡献不大.枯水期,府河水体与沉积物之间的物质和能量交换频繁,硝化作用和反硝化作用受水体与沉积物二者的共同影响.丰水期,河流NH 4+-N主要通过植物吸收去除;NO 3--N减少约86.3%,其中反硝化作用贡献为44.6%,水生植物吸收占到55.4%.因此,通过恢复府河水生植物,可以强化植物对河流NH 4+-N和NO 3--N的吸收,从而缓解白洋淀富营养化状况.

Sources and Transformations of Nitrogen in the Fuhe River of the Baiyangdian Lake

The sources and transformations of nitrogen in the Fuhe River were investigated by application of nitrogen isotope methods. The results showed that the values of delta15N in ammonium and nitrate were 1.35 per thousand-8.01 per thousand and -6.69 per thousand-8.36 per thousand, respectively. The industrial and municipal wastewater from the Baoding City contributed high ammonium to the river. In drying season, the processes of nitrification and denitrification were affected by both of water and sediment. In wetting season, ammonium was mainly absorbed by plants, and loss rate of nitrate was about 86.3%. The nitrate removal by denitrification reached 44.6%, whereas that by plant uptake was 55.4%, indicating the importance of vegetation in nitrogen removal. Thus, restoration of local vegetation in the river would be the key to relieve eutrophication in the lake.