高原湖泊典型农业小流域氮、磷排放特征研究——以凤羽河小流域为例

通过对凤羽河小流域出水口断面进行定位连续监测,计算流域出水量和氮磷排放量,解析了流域氮磷排放量的时间变化特征,以期为小流域氮磷排放量计算、农业管理措施调控、削减流域氮磷排放量提供科学依据.结果表明,凤羽河小流域年度水流量为0.99亿m3,7—9月雨季水流量占全年的43.70%.小流域总氮(TN)的年排放量为139.8 t,可溶性总氮(DTN)是氮的主要排放形式,占TN的71.16%,颗粒态氮(PN)占TN的28.84%.小流域总磷(TP)的年排放量为27.7 t,颗粒态磷(PP)是磷的主要排放形式,占TP的76.47%,可溶性总磷(DTP)占TP的23.53%.7—9月雨季氮磷排放量占全年总量的比例分别为55.33%和77.81%.降雨是影响流域径流过程的重要因素,同时,流域内农业管理措施对径流量和氮磷排放具有较大影响.

Study on characteristics of nitrogen and phosphorus emission in typical small watershed of plateau lakes:A case study of the Fengyu River Watershed

The runoff volume, nitrogen and phosphorus emission in the Fengyu River Watershed were calculated and the temporal changes of nitrogen and phosphorus were analyzed by using the continuous position monitoring data. It could provide the scientific evidences for the assessment of nitrogen and phosphorus emission, regulation of agricultural management and reduction of nitrogen and phosphorus pollution load in the Fengyu River Watershed. The results showed that the annual runoff volume of the Fengyu River Watershed was 0.99×10⁹ m³. The runoff was concentrated in raining season (from July to September), accounted for 43.70%. The annual losses of total nitrogen (TN) and total phosphorus (TP) were 139.8 t and 27.7 t, respectively. Total dissolved nitrogen (DTN) and particulate phosphorus (PP) were separately the main forms of nitrogen and phosphorus emissions. The DTN accounted for 71.16% of TN and particulate nitrogen (PN) accounted for 28.84% of TN. The 76.47% of annual loss of TP was the PP, and total dissolved phosphorus (DTP) accounted for 23.53%. The losses of nitrogen and phosphorus in the raining season accounted for 55.33% and 77.81% for annual discharge, respectively. Rainfall was an important influencing factor for runoff process, and agricultural management also had a greater impact on runoff, and nitrogen and phosphorus losses.