包气带是连接大气层和含水层水分和养分转换的纽带，也是农田NO₃^--N分布和累积的重要场所和向含水层淋失的通道，因此研究包气带土壤中NO₃^--N的分布累积规律对防止地下水NO₃^--N污染至关重要。本文以中国科学院栾城试验站典型的厚包气带为对象，在无施肥处理(N0)和施氮肥600 kg/(hm²·a)(N600)两种处理的多年试验田中，利用Geoprobe获取0 ~ 10.5 m深度土壤样品，研究厚包气带NO₃^--N垂向分布、累积规律，并分析其影响因素。结果表明：N0中NO₃^--N基本保持不变，长年施氮肥600 kg/(hm²·a) 使得NO₃^--N淋溶至10.5 m，并在深层包气带中形成累积，累积的峰值由土壤的质地和含水量决定；NO₃^--N的分布和累积主要受水分运移、土壤质地和反硝化作用影响。

The unsaturated zone is the link which water and nutrient transforms between atmosphere and aquifer, and it is crucial to study the distribution and accumulation of NO₃^--N for preventing nitrate pollution in groundwater because it is the place where farmland nitrate distribute and accumulate and is the channel that nitrate leaches to the aquifer. In this study, the Geoprobe direct push system was employed to obtain 10.5 meters of continuous soil core samples from the typical deep unsaturated zones in croplands under two different fertilization(N0, no nitrogen fertilizer applied; and N600, 600 kg/(hm²·a) nitrogen fertilizer applied in North China Plain in order to analyze the profile distribution, accumulation and key influential factors of NO₃^--N in soils. The results showed that NO₃^--N remained stable in N0, however, in a long-term application of 600 kg/(hm²·a) nitrogen fertilizer (N600), NO₃^--N leached to 10.5 m and accumulated in the deep unsaturated zone, the peak of accumulation was determined by soil texture and moisture content. The distribution and accumulation of NO₃^--N were mainly affected by water migration, soil texture and denitrification.

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国家自然科学基金面上项目 (41471028)和国家自然科学基金重点项目(41530859)资助。