百花湖周边城市近郊小流域氮、磷输出时空特征

Temporal and Spatial Characteristic of Nitrogen and Phosphorus Output in the Suburb Watershed Around the Baihua Lake

识别主要污染物与污染源对于贵阳周边流域水质的控制与管理具有重要的现实意义.于2010年7月~2011年4月连续进行的野外观测实验,研究了贵阳市重要的水源地百花湖水库周边的麦西河小流域氮、磷流失浓度特征,以便为贵阳市城市近郊小流域面源污染治理提供参考.流域有各种源和汇的存在,导致研究流域在不同时间,从上游到下游,各采样点氮输出变化较大.各采样点水体的不同形态氮含量和磷含量随时间变化总体上仍呈现出一定的规律,总氮、硝氮以2010年7月较高,氨氮、亚硝氮和总磷以2010年10月和12月较高.从上游到下游,各采样点水体中不同形态氮含量和磷含量差异减少.在流域下游的河口处,TN含量由3.297 mg·L-1下降为2.793 mg·L-1,TP从0.136 mg·L-1下降到0.098 mg·L-1,但与中游比较,变化不明显,氨氮含量还有所上升.从流域氮、磷输出时空变化特征来看,氮素特别是氨氮和硝态氮通过河道径流途径进入百花湖的风险较高.研究结果可为百花湖周边小流域氮、磷流失治理做参考.

Identification of the main pollutants and sources has important practical significance for the control and management of water quality in Guiyang's surrounding river areas. Based on the continuous field observation of the experiment from July, 2010 to April, 2011, this paper studies the concentration of nitrogen and phosphorus loss characteristics of Maixi river watershed, which is near to Guiyang's important water source-Baihua Lake reservoir, so as to provide a reference for Guiyang suburban small watershed source pollution control. The existence of various sources and sinks in this river basin makes great changes of nitrogen output in each sample point at different times, from upstream to downstream. Although different forms of nitrogen content and phosphorus content in water at each sampling point changes with time, it still presents a certain regularity on the whole. The total nitrogen and nitrate nitrogen in July 2010 are above normal level, and the ammonia nitrogen, nitrate nitrogen and total phosphorus are at high levels in October 2010 and December. The differences of various forms of nitrogen and phosphorus content in water at each sampling point decrease from upstream to downstream. The content of TN decreases from 3. 297 mg·L - 1 to 2. 793 mg·L - 1 ,and the content of TP decreases from 0. 136 mg·L - 1 to 0. 098 mg·L - 1 . Contrast to the upstream, the nitrogen and phosphorus content in the downstream estuary decreases significantly. But the change is not obvious and the content of ammonia nitrogen rises slightly compared with the middle reaches. From the perspective temporal and spatial variation characteristics of nitrogen and phosphorus output in the basin, the nitrogen, especially ammonia nitrogen and nitrate, has a higher risk of getting into the Baihua Lake by river runoff. The results of the study can provide a reference for the governance of nitrogen and phosphorus loss in the watershed around the Baihua Lake.