不同下垫面暴雨径流氮赋存形态分布特性及控制技术

以重庆地区5种用地类型为例,探讨了城市暴雨径流中氮赋存形态的分布特性。研究结果表明,总氮的场次降雨平均浓度（Event Mean Concentrations,EMCs）以交通干道最高（10.6mg/L）,校园汇水区最低（2.4mg/L）;交通干道和商业区暴雨径流氨氮的EMCs（3.4～4.6mg/L）明显大于水泥屋面和瓦屋面（1.2～1.6mg/L）。尽管初期暴雨径流总氮的平均浓度（Partial Event Mean Concentrations,PEMC10）大于EMCs,但氮赋存形态构成并未发现明显区别;氮以溶解性总氮为主（占总氮的73%～82%）,而溶解性总氮中又以无机氮为主（占总氮的63%～82%）;商业区、水泥屋面、校园综合汇水区、瓦屋面暴雨径流中氮赋存形态所占比例最高的均为硝酸根,分别占各自总氮浓度的39%、39%、44%和52%,而城市交通干道的总氮浓度中比重最大的组分为氨氮,占总氮的43%。改良暴雨管理措施可有效提高暴雨径流中总氮的去除率,其关键为人工创造反硝化所需要的条件,延长暴雨径流在控制系统内的水力停留时间,并选择低氮含量的填料作为控制系统的使用材料。

Distribution Characteristics and Control Measures of Nitrogen Composition in Urban Stormwater Runoff from Different Underlying Surfaces

Nitrogen composition in urban stormwater runoff from five underlying surfaces was studied and discussed.It is shown that the highest EMCs of TN（Total Nitrogen） came from urban traffic road（i.e.10.6 mg/L）,and the lowest was from campus catchment areas（i.e.2.4 mg/L）.Meanwhile,EMCs of NH3-N from traffic road and commercial district（i.e.3.4～4.6 mg/L） were much higher than that from concrete roofs and tile roofs（i.e.1.2～1.6 mg/L）.Although PEMC10 of TN was greater than EMCs,the proportion of nitrogen was still similar.Nitrogen in stormwater was predominantly dissolved（73%～82%）,with DIN（Dissolved Inorganic Nitrogen） the abundant form（63%～82% of TN）.The highest concentrations of nitrogen species form commercial district,concrete roofs,campus catchment and tile roofs were NO3-N,which made up of 39%,39%,44% and 52% of TN respectively.However,it was NH3-N that had greatest concentration in runoff from urban traffic road,and the ratio of NH3-N /TN was as high as 43%.The removal of TN could be enhanced through improvement of stormwater management measures.The key factor was that conditions to drive nitrification must be created,retention time of stormwater runoff in treatment systems should be increased and material with low nitrogen content should be selected as construction media.