北京市北运河水系河道水质变化及其对河岸带土地利用的响应

Variation of Water Quality in Urban Rivers of North Grand Canal in Beijing and Its Response to Land Use in Riparian Zone

以再生水为主要补充水源的高度人工化的城市河道已经成为城市水生态系统的主要载体。与自然河道相比,人工化河道水源较为复杂,河道与城市内部的水、热、污染物迁移转化及其响应更为敏感。以北京市再生水补水典型河段清河、北小河、坝河、通惠河为研究对象,分别在2004年和2011年春季和夏季,对再生水补水河道水质进行监测;综合运用Pearson相关分析和DCCA排序分析方法,研究水质要素及其对河岸带不同尺度缓冲区土地利用结构变化的生态响应,通过因子分析,识别水质的污染源。结果表明,与2004年相比,2011年北京市北运河水系河道中,与氮、磷、酸和碱污染相关的水质要素含量的变异系数显著增大,水中有机污染物含量的变异系数明显减小;水体受非点源污染程度在减小,河岸带水域和交通用地对河道水质的影响的空间尺度在缩小,再生水对河道水质的人为调节作用大于生态廊道中其他土地类型的自然调节作用;河道各水质要素的空间分布格局各异。2004年,影响北京市北运河水系河道水污染以氮、磷、酸和碱等的无机污染为主,这不仅与河岸带林地的非点源磷贡献有关,还与有机物降解和硝化作用等影响;2011年,河道水污染偏重于化学需氧量和铵态氮等有机污染,而且还有氮、磷、酸和碱等无机污染。

The highly artificialized urban river course mainly supplemented with reclaimed water has become the main carrier of city aquatic ecosystems. Compared with the natural river, water source in artificialized urban river is much more complex, the transport and transformation of water, heat and pollutants between river and inner-city and their response mode have become more sensitive. In this paper, the typical urban rivers supplemented with reclaimed water （Qinghe River, Beixiaohe River, Bahe River, Tonghuihe River） in Beijing were selected. Water quality was monitored in spring and summer in 2004 and 2011 respectively, through statistical analysis the characteristics of water quality parameters, and combining with the structure variation of land use for the buffers in riparian zones at different scales, integrating Pearson correlation and DCCA analysis, the ecological response mode was explored. Possible pollution sources by Factor Analysis were also analyzed. The results showed that compared to the year of 2004, the variability of water quality associated with nitrogen and phosphorus increased but which associated with organic contamination was reduced in 2011. The influence of non-point source of water was diminishing. The artificial regulation effect of reclaimed water on water quality was greater than those of other types of land in the natural ecological corridors. The spatial patterns of elements of water quality were different. The main factors of water pollutant in 2004 were inorganic matters such as nitrogen, phosphorus, acid and alkali, that can be explained as point source phosphorus contribution from cultivated and wood lands, which was the main pollution sources, accompanied by degradation of organic matter, nitrification and other effects in 2004; in 2011, the main water pollution sources turned to organic matters such as COD and NH4^＋, and also inorganic matters such as nitrogen, phosphorus, acid and alkali.