中文摘要：

以龙门口水库滨岸带湿地为研究对象，以农业径流中氮元素为主要的农业面源污染物，2012年7～9月通过设置植被类型和氮浓度不同的3个采样区进行对比试验，对滨岸带土壤中氮含量、硝化细菌数量及其硝化速率进行了研究。结果表明，表层土壤硝化速率和硝化细菌数量水平分布特征为有农田径流且有水草区〉有农田径流且无水草区〉无农田径流且无水草区，且均随着土壤深度的增加明显降低。从月份变化来看氨氧化细菌（Ammonia-Oxidizing Bacteria，AOB）的数量分布表现为7月〉8月〉9月，与氨氮含量变化趋势基本一致，硝化速率也呈现出夏季大于秋季的特点。对滨岸带土壤硝化作用有显著影响的因子为AOB的数量、氨氮、总氮、总磷含量、含水率和温度，从而进一步证实了氨氧化是硝化作用的限制性步骤。

英文摘要：

Nitrogen, nitrobacteria, nitrification rates and their impact factors were discussed in the riparian zone of Longmenkou reservoir with agricultural runoff in July, August and September 2012. The result showed the number of ammonia-oxidizing bacteria （AOB） and nitrification rates at the area with agricultural runoff and hydrophytes were highest, ranged from 65.0 × 10^4 to 110 × 104 cells · g^-1 and from 25.75 to 45.21 mg · kg^-1 · d^-1 in top soils respectively. And the numbers of AOB and nitrification rates obviously decreased with the increase of soil depth. The numbers of AOB increased from July to September, which was similar to the change of NH^4＋-N concentrations. The characteristic of nitrification rates showed that summer was faster than autumn. The number of AOB, NH4^＋-N, TN, TP, moisture content and temperature were key impact factors of nitrification in the riparian zone of Longmenkou reservoir. The phenomena further verified that the ammonia oxidation is limiting step of nitrification.