典型山地丘陵区农业小流域氮素迁移特征

A Study on the Nitrogen Transportation Process and Flux in a Small Agricultural Watershed of Hilly Landscape

为探讨山地丘陵区农业小流域氮素迁移特征,对典型山地丘陵区农业小流域降雨—径流事件、水体氮素形态与浓度、时间变异特征及其迁移通量进行了全年观测研究。结果表明:(1)小流域水体氮素浓度存在显著季节变异特征,全年总氮(TN)平均浓度为2.14 mg/L,硝态氮(NO3-—N)平均浓度为0.77 mg/L,铵态氮(NH4+—N)平均浓度为0.25 mg/L,溶解性有机氮(DON)平均浓度为0.51 mg/L,其中NO3-—N是氮素迁移的主要形态;(2)小流域春季(3—5月)对全年氮素迁移通量贡献最高(43.56%),而秋季(9—11月)贡献率最低(3.70%);(3)降雨—径流事件和施肥等农事活动是小流域氮素迁移及其通量的重要驱动因子。

To better explore the characteristics of nitrogen transportation in a small typical agricultural catchment,the water nitrogen form,concentration and loss fluxes were continuously monitored for one year.The results showed that:(1)During the observation period,the significant seasonal variations in water nitrogen concentrations were observed and the year-round average concentration of total nitrogen(TN),nitrate nitrogen(NO3-—N),ammonium nitrogen(NH4+—N),and dissolved organic nitrogen(DON)are 2.14 mg/L,0.77 mg/L,0.25 mg/L,and 0.51 mg/L,respectively;the NO3-—N is the main form of transported N in the small catchment.(2)In the spring(March to May),the N transport fluxes contributed for 43.56%of the annual total nitrogen fluxes,while in autumn(September to November),the N transportation fluxes only accounted for 3.70%of annual total N transportation fluxes.(3)The run-off and human activity are the major drivers of the nitrogen transportation in the small agricultural watershed of hilly landscape.