密云水库上游流域非点源氮流失特征研究

利用密云水库上游流域2001年、2004年地表水质监测数据,从流域土地利用和景观格局特征出发,分析了非点源氮流失的时空差异以及影响因素。结果表明:雨季中水体中氮污染物的浓度明显高于雨季后的浓度,硝态氮(NO3--N)是是氮在地表水环境的主要存在形式,而且与总氮(TN)呈很好的线性关系;村庄、农地等人类活动比较剧烈的流域,氮的季节变异较大;而在有稳定水源或径流季节变异较小的流域,氮的季节变异较小;不同的景观分布格局也对氮的流失产生影响,源景观更靠近监测点氮污染物浓度要高于汇景观更靠近监测点的氮污染物浓度;在坡度较大的东北和西北地区,(TN)和(NO3--N)的浓度要明显大于坡度较小的库北地区。

LOSS OF NITROGEN AT THE WATERSHED OF THE MIYUN RESERVOIR

The temporal and spatial variations of nitrogen loss and the effect of watershed characteristics on nitrogen loss of the Miyun Reservoir were studied in this paper.The result showed that the concentrations of nitrogen in rainy seasons are higher than those in normal seasons,and NO3--N which is linearly related to the total N is the main existing form;the seasonal variation of nitrogen at the watershed with strong influence of human activity is much more significant than that at the watershed with steady water source;woodland and grassland can prevent and filtrate nitrogen effectively,landscape pattern also has an important effect on nitrogen loss,concentration of nitrogen in sampling site near the source landscapes is higher than that of the sampling site near the sink landscapes;the northwestern and northeastern areas with high slopes have much higher concentrations of nitrogen than in the northern area.