底泥原位洗脱过程中氮磷含量与形态变化特征

随着城市化进程的不断推进，城市河流底泥中内源氮磷污染问题日益突出.为研究原位洗脱技术对污染底泥中氮、磷物质和成分的作用效果，以北京市凉水河作为研究对象，分别比较了现场试验洗脱与对照组0~30 cm分层底泥以及实验室模拟洗脱处理前后0~10 cm底泥中pH、E_h（氧化还原电位）、容重、含水率、OM（有机质）、TN、TP和氮、磷形态分布的变化特征.结果表明:①现场洗脱对0~5 cm厚度底泥的处理和模拟洗脱处理均对底泥中pH、E_h、含水率的改变以及其中TN、TP的去除效果表现显著，其中，现场试验洗脱组0~5 cm范围底泥中w（TN）、w（TP）分别较对照组降低了66.4%±17.4%、40.8%±24.4%，模拟洗脱处理对底泥中OM、TN、TP的去除率分别达70.1%±4.8%、66.8%±2.0%、43.1%±3.1%.②原位洗脱技术对底泥中TN的去除主要通过对PON（颗粒态有机氮）的去除来实现，现场和模拟试验过程中PON对TN去除的贡献率分别达55.0%和73.6%.③原位洗脱对底泥中TP的去除主要通过对Al-P（铝结合态磷）、OP（有机磷）的去除来实现，现场和模拟试验中Al-P、OP对TP去除的贡献率分别达37.0%、66.2%和31.3%、43.7%.研究显示，原位洗脱技术可有效去除城市河流底泥处理层中的氮磷物质，并以有机氮、磷物质的去除为主. 

Changing Characteristics on Contents and Forms of Nitrogen and Phosphorus in Sediment during in-situ Physical Elution

The internal pollution from nitrogen (N) and phosphorus (P) of sediment in urban rivers has been increasingly notable with the urbanization. In order to study the removal efficiency of in-situ physical elution technology, sediments from Liangshui River in Beijing were selected as subject. The distribution characteristics of pH, E_h, volume weight, moisture content, organic matter (OM), TN, TP as well as N and P forms among treatment and control group on-site (depth from 0 to 30 cm) so as the simulated test (depth in 10 cm) in laboratory were compared and studied in the pre and post of treatment. The results were as follows:(1) Change of pH, E_h, moisture content as well as removal of nutrients in sediments were significant both in on-site (depth in 0-5 cm) and simulated (depth in 10 cm) treatments. The content of TN and TP of on-site engineering group (depth in 0-5 cm) were reduced by 66.4%±17.4% and 40.8%±24.4%, respectively. The removal rate of OM, TN, TP were reached 70.1%±4.8%, 66.8%±2.0% and 43.1%±3.1% in simulated treatment, respectively. (2) The removal of TN was mainly achieved by the reduction of particulate organic nitrogen (PON), whose contribution ratios to TN-removal on site and in simulated test reached 55.0% and 73.6%, respectively. (3) The removal of TP was mainly achieved by the reduction of Al-bound P (Al-P) and organic P (OP) whose contribution ratios to TP-removal on site and in simulated test reached 37.0%, 66.2% and 31.3%, 43.7%, respectively. In summary, the results showed that the in-situ physical elution technology has an obvious removal on the N and P content of sediment in urban rivers, especially the organic N and P components.