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研究长三角典型都市农业村镇不同土地利用下的氮素非点源输出特征,以期为治理该区域的面源污染提供科学依据.通过典型次降雨径流事件中氮形态和输出负荷变化的研究发现:监测点总氮(TN)的事件平均浓度(EMC)为20.01～22.83mg/L,其中溶解态氮(DN)占TN的比例最大;研究区非点源氮流失以溶解态为主,DN又以溶解态有机氮(DON)为主.耦合各形态氮浓度与径流量特征,发现非点源氮素输出呈现2个峰值,且出现在径流峰值之前4～55min;TN、DN和硝态氮(NO3--N)浓度随降雨时间增加呈现减少趋势;氮素负荷受其浓度和径流量的共同作用,基本上呈现与氮素浓度相同的变化特征,但起伏变化较为平缓.氮素污染负荷积累曲线分析表明,村域地表径流各形态氮素均存在初期冲刷效应.
This paper studies the characteristics of nitrogen non-point source output under different land use in typical urban agricultural villages and towns of the Yangtze River Delta to provide a scientific basis for the management of non-point source pollution in this area.By studying the nitrogen form and output load changes in typical sub-rainfall runoff events, The average concentration of total nitrogen (TN) in the monitoring sites was 20.01 ~ 22.83 mg / L, of which dissolved nitrogen (DN) accounted for the largest proportion of TN. In the study area, The dominant organic nitrogen (DON) was coupled with the characteristics of nitrogen concentration and runoff. The results showed that the nitrogen output of non-point source showed two peaks at 4 ~ 55min before the peak of runoff. The TN, DN and nitrate nitrogen (NO3 - N) concentration tended to decrease with the increase of rainfall time. The nitrogen load basically showed the same variation with the nitrogen concentration, but the fluctuation was more moderate. Accumulation curve analysis shows that there is an initial scouring effect on all forms of nitrogen in surface runoff in the village.