城市雨水管道沉积物氮磷污染溶出特性试验研究

针对城市雨水管道沉积物氮磷溶出特性不清楚的问题，以南京江北新区3种不同功能区（文教区、交通区及商业区）分流制雨水管道为研究对象，考察了管道沉积物中氮磷溶出随时间的变化关系，分析了不同pH、盐度等环境因素下氮磷溶出特征，并探讨了不同氮磷浓度的来流对出流中氮磷的影响.结果表明:①各功能区管道沉积物中溶出ρ（NH₃-N）、ρ（NO₃-N）、ρ（TP）随淋溶时间先增大后趋于稳定，且达到峰值的先后顺序均表现为交通区>文教区>商业区.②各功能区管道沉积物中NH₃-N和TP在pH影响下溶出趋势基本一致，均表现为酸性条件>碱性条件>中性条件，而NO₃-N溶出均在pH=7附近（中性条件）达到峰值（交通区溶出率最大，为35.21%）.③各功能区管道沉积物中NH₃-N和NO₃-N的溶出均随盐度增加而逐渐增加，而TP的溶出却在盐度超过1%后呈不同程度的波动.④NO₃-N溶出率最小且TP溶出率最大的交通区雨水管道出流受来流影响最明显，相关系数均超过0.97.研究显示，与文教区、商业区相比，pH、盐度等环境因素对交通区雨水管道沉积物氮磷溶出影响最大，在雨水管道径流氮磷输出负荷的定量评估过程中应被重点关注. 

Experimental Study on Leaching Characteristics of Nitrogen and Phosphorus in Urban Rainwater Pipeline Sediment

In order to determine the leaching characteristics of nitrogen and phosphorus in urban rainwater pipeline sediments, three different functional areas (education area, traffic area and commercial area) of rainwater pipeline in Nanjing Jiangbei new district were taken as the research object. The relationship of nitrogen and phosphorus in sediments with leaching time was investigated. The leaching characteristics for both nitrogen and phosphorus under different environmental factors such as pH and salinity were analyzed. The effect of nitrogen and phosphorus in the influent on the corresponding effluent was discussed. The results showed that: (1) The leaching rate of ρ(NH₃-N), ρ(NO₃-N), ρ(TP) in the sediments of the three functional areas increased first, and then stabilized with the increase of leaching time. The order to reach leaching equilibrium was in the order traffic area > education area > commercial area. (2) The influence of pH on both NH₃-N and TP in the sediments of the three functional areas was basically the same, with the leaching trend of acid condition > alkaline condition > neutral condition. The leaching rate of NO₃-N reached the peak at pH = 7 (neutral condition). The leaching rate (35.21%) in traffic area was the highest. (3) The leaching rates of NH₃-N and NO₃-N increased with the increase of salinity. The leaching rate of TP fluctuated to different degrees when the salinity was higher than 1%. (4) The influent had the most significant influence on the effluent in the traffic area with the lowest NO₃-N leaching rate and the largest TP leaching rate, and the correlation coefficients were all greater than 0.97. Overall, compared with education and commercial areas, environmental factors such as pH and salinity had the greatest impact on the release of nitrogen and phosphorus from rainwater pipeline sediments in traffic area, which should be seriously considered when quantitatively assessing nitrogen and phosphorus output load from rainwater pipeline.