• 关键词：干沉降  氨氮  推算法  替代面法  水库型水源地  农业

• 基金项目：国家自然科学基金（No.U1704241，42007175）；中原科技创新领军人才项目（No.194200510010）；高等学校基本科研业务费（No.NSFRF200326）

• 陈晓舒
• 河南理工大学资源环境学院，焦作 454000

• 赵同谦
• 河南理工大学资源环境学院，焦作 454000

• 任玉芬
• 北京京津冀区域生态环境变化与综合治理国家野外科学观测研究站，北京 100085

• 肖春艳
• 河南理工大学资源环境学院，焦作 454000

• 贺玉晓
• 河南理工大学资源环境学院，焦作 454000

• 陈飞宏
• 河南理工大学资源环境学院，焦作 454000

• 张清淼
• 河南理工大学资源环境学院，焦作 454000

• 摘要：农业源氨氮沉降是水库型水源地水体收到的重要的外源氮之一，其沉降量评估与来源识别是水体氮污染防控的重要依据.替代面法和推算法是大气氮素干沉降监测的两种常用方法.采用替代面法和推算法，于2019年9月—2020年8月对淅川库区周边设置的5个大气监测点进行干沉降样品采集，测定了样品中氨氮浓度及其氮同位素，探讨了2种监测方法在氨氮干沉降通量估算及氨氮来源解析中的适用性.结果表明：替代面法获得的氨氮干沉降通量为推算法的1.4~2.1倍，2种监测方法获得的氨氮干沉降通量在时空变化趋势上具有一致性；推算法获得的δ¹⁵N-NH₄⁺较替代面法偏负，季均相差为11.1‰，时空差异显著.替代面法在获得淅川库区氨氮干沉降通量方面具有优势，受氨氮分馏影响，直接获得的δ¹⁵N-NH₄⁺值较初始源δ¹⁵N-NH₃值存在较大偏差，影响溯源结果的准确性；推算法能够分别获得不同氨氮形态干沉降中的δ¹⁵N-NH₄⁺值，适用于氨氮干沉降来源分析，但易造成氨氮干沉降通量偏低；综合利用2种监测方法能够提高同位素溯源结果的准确性.

• Abstract：The entry of nitrogen deposition in the form of ammonia released from the agricultural source is one of the important exogenous nitrogen sources in reservoir type water source. Assessment of its deposition fluxes and identification of source can provide an important reference for the prevention and control of water nitrogen pollution. The alternative surface and extrapolation methods are two commonly used methods used in measuring dry nitrogen deposition fluxes. In the present study， both the methods were used to collect the dry deposition samples from five atmospheric monitoring station set around Xichuan Reservoir from September 2019 to August 2020. Ammonia nitrogen concentration and nitrogen isotopes （δ¹⁵N-NH₄⁺） for the samples were measured， and the applicability of the two methods in the estimation of ammonia-nitrogen deposition fluxes and ammonia sources were discussed. The results showed that dry ammonia-nitrogen deposition fluxes obtained by the alternative surface method was 1.4~2.1 times higher than that by extrapolation method， and the dry deposition fluxes obtained by both methods were consistent in spatial-temporal trend. Compared to alternative surface method， the δ¹⁵N-NH₄⁺ obtained by extrapolation method was negative. The result showed significant temporal and spatial differences with a seasonal average difference of 11.1‰. The alternative surface method showed an advantage in obtaining dry ammonia-nitrogen deposition fluxes in Xichuan Reservoir. δ¹⁵N-NH₄⁺ values directly showed a large deviation from the initial δ¹⁵N-NH₃ values from sources because of their fractionation， which had influence in tracing sources. Extrapolation method was suitable for identification sources of dry ammonia-nitrogen because δ¹⁵N-NH₄⁺ values in different forms can be obtained by the method. However， it can lead to the low dry deposition fluxes. Our results indicated that the comprehensive utilization of the two measuring methods can improve the accuracy of the isotope traceability results.

• Key words：dry deposition  ammonia nitrogen  extrapolation method  alternative surface method  reservoir type water sources  agriculture

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