雨水收集系统结合自循环系统下的景观湖体氮磷特征

为评估采用雨水作为城市景观湖体补充水源的富营养化发生风险，以天津文化中心景观湖为研究案例，分析了其典型的2套运营系统：雨水收集系统（雨水经沉淀井、蓄水模块和垂直潜流湿地进入景观湖）和中心湖水体的循环及净化系统（湖水抽排至垂直潜流湿地再进入景观湖）中景观湖的氮磷浓度变化规律。采用2015年3-10月的长期监测，研究湖中氮磷营养盐的时间变化趋势以及形态变化规律，提取影响湖中氮磷浓度的因素。结果表明：2015年3-10月景观湖中总氮和总磷平均浓度分别为（1.551±0.491）mg·L-1和（0.058±0.029）mg·L-1，溶解态氮和磷分别占71.7%和50%，系统运行稳定时总氮和总磷浓度主要分布在1.0~1.3 mg·L-1和0.029~0.05 mg·L-1之间；总体上，溶解态氮为湖水中氮存在的主要形式，而磷则主要以颗粒态形式存在，在降雨条件下，部分污染物随着降雨冲刷进入湖体，因此景观湖中溶解态磷的浓度增高；湿地是否稳定运行是影响景观湖中总氮、溶解态氮以及总磷浓度的因素，而降雨条件是影响景观湖体的总磷浓度以及溶解态磷浓度的因素；景观湖的富营养化风险较低，降雨期间进入湖体的溶解态磷是最大的风险因子。

Characteristics of nitrogen and phosphorus in urban lake using water collection system and circulation system

To assess the potential risk of eutrophication in a landscape lake supplied by stormwater,this study focused on Tianjin Culture Park where two typical landscape lake systems,the stormwater collection system (stormwater passed through sedimentation manholes,storage modules,and vertical-flow constructed wetland)and the circulation and purification system (the lake water is pumped out into the wetland and back into the lake again),were analyzed,and the nutrients characteristics of the lake were determined. This research describes nutrients monitoring of the landscape lake from March to October 2015,with an analysis of the temporal characteristics and different forms of nitrogen and phosphorus for the lake,combined with natural and human factors extracted. The results indicated that from March to October 2015,the average concentrations of TN and TP in the lake were (1.551±0.491)mg·L-1 and (0.058±0.029) mg·L-1,respectively,and DTN and DTP accounted for 71.7% and 50%. When the system was operating stably,the concentrations of TN and TP were between 1.0 to 1.3 mg·L-1 and 0.029 to 0.05 mg·L-1,respectively. Dissolved nitrogen was the main form of nitrogen,whereas particulate phosphorus was the main form of phosphorus,in the lake. During rainfall,some pollutants in the runoff washed into the lake,which resulted in an increased concentration of dissolved phosphorus. The wetland operating status was the main factor affecting TN and DTN concentrations,whereas TP and DTP concentrations were influenced mainly by rainfall. The risk of eutrophication in this urban lake is low,except during rainfall when dissolved phosphorus is a big risk factor for eutrophication.