农业面源氮素已成为影响三峡库区环境安全的主要因素，但有关农业面源氮污染研究并未深入区分氮污染主要来自何种农业用地，同时以什么方式进入三峡库区。以三峡库区紫色土农用坡地为研究对象，对典型农耕模式下碳铵、尿素和复合肥的氨挥发特征以及小流域内氮素收支平衡进行分析，以期探究氨挥发对三峡库区氮污染的影响。采用原位受控对照实验的范式进行研究，结果表明，在典型农耕模式下，三峡库区紫色土氨挥发速率表现为：复合肥最低，变化最平缓；尿素的峰值出现滞后，下降缓；碳铵的峰值出现较早，下降快。小流域内尿素的氨挥发率为8.82%~18.37%，碳铵为17.86%~30.70%，复合肥为2.56%~3.86%。施肥种类的氨挥发率大小为：碳铵 > 尿素 > 复合肥，典型用地的氨挥发率大小为：水田 > 果林 > 旱地。对流域内氮收支平衡分析，发现小流域内化肥是氮素最主要的输入，氨挥发是主要的输出，土壤氮素残留严重，增加了氮素流失风险。从环保角度考虑，降低三峡库区碳铵使用频率、减少旱地和果林施肥量、优化氮肥施用结构是减少氨挥发的有效途径，氨挥发率的减少对三峡库区氮污染防治具有重要意义。
Agricultural non-point source nitrogen has become the main source of environmental safety in the Three Gorges Reservoir. However, investigation on agricultural non-point source nitrogen pollution has not been studied in depth which agricultural land was the main source, and how to enter Three Gorges Reservoir. Purple soil sloping ploughland in Three Gorges Reservoir was taken as the studied object to explore the effect of ammonia volatilization on nitrogen pollution. The ammonia volatilization characteristics of ammonium bicarbonate, urea and compound fertilizer in typical farming modes, and the nitrogen budget in a small watershed were investigated. The study was conducted by using a paradigm of controlled experiments in situ. The results show that the ammonia volatilization flux of compound fertilizer is the lowest and the change is the most gradual. Meanwhile, the peak value of ammonia volatilization flux of urea lags behind and decreases slowly, while that of ammonium bicarbonate appears earlier and decreases faster. The ammonia volatilization loss ratio of urea, ammonium bicarbonate and compound fertilizer in the watershed are 8.82%~18.37%, 17.86%~30.70% and 2.56%~3.86%, respectively. Besides, the ammonia volatilization loss ratio is in order:ammonium bicarbonate > urea > compound fertilizer, and the ammonia volatilization loss ratio between typical land use is in order:paddy field > fruit forest > dry land. Moreover, it is found that chemical fertilizer and ammonia volatilization are the most important nitrogen inputs and outputs in the watershed, and soil nitrogen residues are serious, which increases the risk of nitrogen loss. From the perspective of environmental friendliness, reducing the frequency of ammonium bicarbonate use, reducing the amount of fertilizer applied to dry land and fruit forest, and optimizing the application structure of nitrogen fertilizer in the Three Gorges Reservoir are effective ways to reduce ammonia volatilization. The reduction of ammonia volatilization is of great significance for the prevention and control of nitrogen pollution in the Three Gorges Reservoir.